|
![Reply](https://smith-wessonforum.com/images/blue_style/buttons/reply.gif) |
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 02:10 AM
|
![LVSteve's Avatar](https://smith-wessonforum.com/image.php?u=119432&dateline=1275775928) |
Member
|
|
|
Join Date: Feb 2005
Location: Lost Wages, NV
Posts: 20,465
Likes: 25,275
Liked 30,094 Times in 11,202 Posts
|
|
Rant: Another gun rag gets .308 vs 7.62 NATO wrong
Doncha just love how certain inaccuracies become fact and refuse to die no matter how many times the truth is spoken. Yes, it's 7.62 NATO vs .308 Winchester AGAIN. Shooting Times trotted out the old fiction about .308 Win being a 62,000 psi cartridge and 7.62 NATO is only 50,000, so has much less pressure. WRONG,WRONG thrice again WRONG.
The 62,000 psi figure for 308 Winchester is the latest SAAMI pressure measured using a piezo pressure transducer. The value for 7.62 NATO comes from an old Copper Units of Pressure (CUP) style measurement, and the answer is indeed 50,000 CUP. It's like saying the distance between two points is 62 miles and somebody says, "No, it's much further, like 100 km". Unfortunately there is no "laws of physics" based PSI to CUP conversion, but empirical data does show a relationship. http://www.shootingsoftware.com/ftp/psicuparticle2.pdf
Shortly, somebody will appear and say "Ah, but it's 50,000 psi CUP". There's no such unit of measure. It's like measuring your inseam in grand pianos per decade. Don't go there.
If you compare .308 Win and 7.62 NATO as specified by the European standards folks at CIP, Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives - Wikipedia, the free encyclopedia, lo and behold they are both rated at the same pressure. C'mon now, you're not really surprised, are you?
Yes, the SAAMI spec for the .308 Win CASE is not the same as that for 7.62 NATO. The latter has thicker walls at the head for use in automatic weapons with generous headspace, so it has a little less capacity than .308 Win. Big deal. Go look at the velocity specs listed by any of the big manufactures and you will see they are usually identical for bullets of the same weight. Does that sound like the extra case capacity is making much difference, or that one runs at 20% more pressure than the other? No, it doesn't work for me, either.
Last edited by LVSteve; 06-21-2014 at 05:22 PM.
Reason: Missed a word out
|
The Following 34 Users Like Post:
|
18robert, Aggie1906, Bekeart, brucev, CH4, desi2358, Echo40, Greyman50, growr, hkcavalier, ImprovedModel56Fan, jag312, JPriest, klausinak, KLYDE, Krogen, Kurusu, LostintheOzone, malph, Model 15-4ever, nawilson, old tanker, OrlontheBrave, PAFMAN3, rojodiablo, Rubone, rwsmith, rwt1405, shouldazagged, Skyhunter, Steve912, TAROMAN, TOM BECKWITH, zipty6 |
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 02:30 AM
|
![coltle6920's Avatar](https://smith-wessonforum.com/image.php?u=236841&dateline=1382940151) |
Member
|
|
|
Join Date: Oct 2013
Location: Denver,Colorado
Posts: 4,297
Likes: 5,807
Liked 8,322 Times in 2,490 Posts
|
|
I'll just pretend I understand what you're talking about.I'm still awed by the fact that socks can go on either foot.
|
The Following 55 Users Like Post:
|
18robert, 46er, ACORN, Aggie1906, Alk8944, ameridaddy, armenius, Baxter6551, Beemerguy53, bgrafsr, bhayles, bruce5781, DesertFox, Dio, don5, Engineer1911, Evil Dog, GB, Grayfox, growr, gwpercle, ImprovedModel56Fan, jaguargolf, Jessie, Llando88, martybee, mckenney99, Muley Gil, OrlontheBrave, OutAtTheEdge, PAFMAN3, REM 3200, Roadtrash, Rule3, rwsmith, rwt1405, semperfi71, Sgt911, shouldazagged, sigp220.45, sipowicz, Skeet 028, skeetshooter, Skyhunter, smokindog, SMSgt, Stan O, Swiftflyer, The Celt, therevjay, TIMETRIPPER, TripLeader, Weimar, yaktamer, zx9rt1 |
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 06:23 AM
|
Member
|
|
|
Join Date: Jan 2008
Location: Harlem, Ohio
Posts: 14,605
Likes: 23,965
Liked 26,783 Times in 9,264 Posts
|
|
Steve, have a cup of tea. Relax in the fact that you are smarter than most gun rag writers and fact checkers and probably more than a few editors! Ivan
|
The Following 4 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 06:42 AM
|
![Engineer1911's Avatar](https://smith-wessonforum.com/image.php?u=134721&dateline=1289881000) |
US Veteran
|
|
|
Join Date: Aug 2007
Location: Augusta, GA
Posts: 6,077
Likes: 6,683
Liked 6,192 Times in 2,685 Posts
|
|
Steve,
Could you please review 223 Rem vs. 5.56 Nato for us? I am also a little fuzzy on 308 vs. 30-06.
Thank you
__________________
S&WHF 366
|
The Following 5 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 07:00 AM
|
Member
|
|
|
Join Date: May 2006
Posts: 699
Likes: 371
Liked 237 Times in 101 Posts
|
|
slow down there brother..........ya need to come inside outta that heat
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 07:29 AM
|
![ChattanoogaPhil's Avatar](https://smith-wessonforum.com/image.php?u=157077&dateline=1262100148) |
Member
|
|
|
Join Date: Oct 2009
Posts: 14,602
Likes: 7,937
Liked 20,626 Times in 5,958 Posts
|
|
Can .308 and 5.56 be shot from the same barrel, or is that .223 and 7.62? The lower on my AR is marked multi caliber so I figure I'm ok but just wanted to make sure.
|
The Following 13 Users Like Post:
|
5BeansintheWheel, ACORN, Aggie1906, Aticus, don5, hkcavalier, LVSteve, mckenney99, Old TexMex, REM 3200, rwt1405, therevjay, TIMETRIPPER |
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 07:30 AM
|
Member
|
|
|
Join Date: Feb 2013
Location: Western NC
Posts: 358
Likes: 12
Liked 267 Times in 125 Posts
|
|
Quote:
Originally Posted by coltle6920
I'll just pretend I understand what you're talking about.I'm still awed by the fact that socks can go on either foot.
|
They can??? Then why have I been putting a L and R on them all these years? Years ago I had to change my name. The only underwear I could find already had the name Calvin on them. Couldn't find any with my original name...............
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 07:55 AM
|
![O2Guy's Avatar](https://smith-wessonforum.com/image.php?u=175646&dateline=1410514051) |
Member
|
|
|
Join Date: Feb 2011
Location: Texas
Posts: 1,021
Likes: 509
Liked 1,126 Times in 412 Posts
|
|
Is it safe to shoot .308 +P in my Model 10?
|
The Following 2 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 08:03 AM
|
SWCA Member
|
|
|
Join Date: Dec 2013
Location: florida
Posts: 5,734
Likes: 3,636
Liked 2,183 Times in 1,425 Posts
|
|
as long as it go s boom and hits the target thats all i care about
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 08:12 AM
|
Member
|
|
|
Join Date: Jan 2012
Location: Outside Philadelphia Pa
Posts: 16,601
Likes: 7,342
Liked 17,200 Times in 7,303 Posts
|
|
308 was a copy of the 7.5 French!
Sent from my SCH-I545 using Tapatalk
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 10:27 AM
|
![Alpo's Avatar](https://smith-wessonforum.com/image.php?u=127063&dateline=1329766462) |
Member
|
|
|
Join Date: Sep 2006
Location: N/W Florida
Posts: 5,694
Likes: 2,450
Liked 6,256 Times in 2,442 Posts
|
|
Everyone is having fun with this, but this is a serious question.
Why would anyone write a formula "X equals negative Z plus 1.5 Y", instead of "1.5 Y minus Z"?
Look at the formula listed on page 4. PSI = -18000 + 1.5CUP (I rounded the numbers - sue me).
Why not say "PSI = 1.5CUP - 18000"? That's the way I learned to write formulas, waaaaaay back in high school algebra class.
__________________
I always take precautions
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 10:31 AM
|
![Alpo's Avatar](https://smith-wessonforum.com/image.php?u=127063&dateline=1329766462) |
Member
|
|
|
Join Date: Sep 2006
Location: N/W Florida
Posts: 5,694
Likes: 2,450
Liked 6,256 Times in 2,442 Posts
|
|
Oh yeah, and thanks for posting that article. That was extremely interesting.
__________________
I always take precautions
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:15 AM
|
![kozmic's Avatar](https://smith-wessonforum.com/image.php?u=197466&dateline=1463317871) |
Member
|
|
|
Join Date: Apr 2012
Location: Western New York
Posts: 5,977
Likes: 15,614
Liked 10,953 Times in 3,687 Posts
|
|
In the future Steve if you are going to start a thread like this please attach a picture of a bird too. I need something to help when my eyes glaze over. Thank you.
__________________
paws for friendship
|
The Following 3 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:19 AM
|
US Veteran
|
|
|
Join Date: Apr 2012
Location: Charles Town, WV
Posts: 4,159
Likes: 959
Liked 1,923 Times in 1,129 Posts
|
|
OK lets all calm down and take it easy. The next thing to come up will be the age old.
magvclip.jpg
__________________
Psalm 23:4
|
The Following 3 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:43 AM
|
![ChattanoogaPhil's Avatar](https://smith-wessonforum.com/image.php?u=157077&dateline=1262100148) |
Member
|
|
|
Join Date: Oct 2009
Posts: 14,602
Likes: 7,937
Liked 20,626 Times in 5,958 Posts
|
|
Quote:
Originally Posted by Alpo
Everyone is having fun with this, but this is a serious question.
Why would anyone write a formula "X equals negative Z plus 1.5 Y", instead of "1.5 Y minus Z"?
Look at the formula listed on page 4. PSI = -18000 + 1.5CUP (I rounded the numbers - sue me).
Why not say "PSI = 1.5CUP - 18000"? That's the way I learned to write formulas, waaaaaay back in high school algebra class.
|
Yeah ok.... I'm still recovering from the truck tire circumference odometer reading gasoline expense account thread.
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:53 AM
|
![Mcwsky09's Avatar](https://smith-wessonforum.com/image.php?u=222911&dateline=1396015544) |
Member
|
|
|
Join Date: Mar 2013
Location: The North Coast
Posts: 1,517
Likes: 148
Liked 1,173 Times in 549 Posts
|
|
Quote:
Originally Posted by coltle6920
I'll just pretend I understand what you're talking about.I'm still awed by the fact that socks can go on either foot.
|
That's nothin, how about latex gloves, no matter whether you need only a right or only a left hand glove or both you ALWAYS get what you need when you pull them out of the box. How does it know?
|
The Following 7 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 12:00 PM
|
![zzzippper's Avatar](https://smith-wessonforum.com/image.php?u=233894&dateline=1397768786) |
Member
|
|
|
Join Date: Aug 2013
Location: St. Louis area
Posts: 3,751
Likes: 1,587
Liked 5,186 Times in 1,935 Posts
|
|
I wish my life was that small.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 12:02 PM
|
Absent Comrade
|
|
|
Join Date: Feb 2013
Location: Louisville, KY, USA
Posts: 19,336
Likes: 53,737
Liked 38,389 Times in 11,802 Posts
|
|
Steve, you've illustrated another reason that except for checking out Ayoob's articles occasionally I don't bother with the gun rags. They're mostly advertising circulars now anyway. And I don't mean just the undisguised ads.
As for the ribbing, I have a touch of OCD myself...
__________________
Oh well, what the hell.
|
The Following 3 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 12:30 PM
|
![Road Rat's Avatar](https://smith-wessonforum.com/image.php?u=156815&dateline=1558320050) |
US Veteran
|
|
|
Join Date: Oct 2009
Location: Iowa
Posts: 2,835
Likes: 3,726
Liked 2,322 Times in 999 Posts
|
|
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 12:50 PM
|
Member
|
|
|
Join Date: Mar 2010
Location: Breckenridge Hills, MO
Posts: 1,910
Likes: 1,594
Liked 1,487 Times in 705 Posts
|
|
Uhhhhh question: don't the copper crushers used to measure CUP come with taridge (sp) tables that give a conversion to psi for the measured length of the crusher? I'm not an engineer and I didn't stay in a Holiday Express last night but I read that in a couple books several years ago.
__________________
Quando omni flunkus moritati.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 01:05 PM
|
Member
|
|
|
Join Date: Jan 2003
Location: Rural NW Ohio
Posts: 3,387
Likes: 5,180
Liked 2,444 Times in 1,097 Posts
|
|
Quote:
Originally Posted by ChattanoogaPhil
Yeah ok.... I'm still recovering from the truck tire circumference odometer reading gasoline expense account thread.
|
All for naught, too, since the guy I was working for never reimbursed me a cent anyway(didn't even offer).
Andy
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 01:27 PM
|
Member
|
|
|
Join Date: Sep 2012
Posts: 37
Likes: 0
Liked 30 Times in 20 Posts
|
|
Everytime I have to explain the 308/7.62 223/5.56 nonsense I feel like my head is going to explode. I wish we could go back to the 80's when nobody gave to bits and there was no such thing as a 77gr 5.56NATO. it was a non-issue until the internet.
|
The Following 3 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 02:06 PM
|
US Veteran
|
|
|
Join Date: Oct 2001
Location: BELTON, SC, USA
Posts: 1,723
Likes: 427
Liked 606 Times in 340 Posts
|
|
LVSteve - thanks for good informative article. A shame so much BS followed it. Interesting question on the .223 VS 5.65 - if you have this comparison, would appreciate seeing what you turn up. Get the feeling the results are similar to the 308 VS 7.65 pressure measurements. Would be good to see all such data on a common base, but we can't seem to go from the old English measurements to Metric which is a better system for calculation. Again thanks for useful data.
__________________
TOMBECK
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 02:07 PM
|
Member
|
|
|
Join Date: Aug 2012
Posts: 1,494
Likes: 474
Liked 1,447 Times in 670 Posts
|
|
Who likes exponentiation?!
Try THIS on for size:
piezo = crusher * ( 1 + ( crusher^2.2 )/30000 )
This formula is supposedly good for converting CUP values between 0-60 ksi. Beyond 60 ksi, conversions become progressively more inaccurate. Not that converting CUP to PSI was ever an exact science to begin with...
Does your head hurt yet?
|
The Following 2 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 02:14 PM
|
![BaldEagle1313's Avatar](https://smith-wessonforum.com/image.php?u=184296&dateline=1313777444) |
Member
|
|
|
Join Date: Aug 2011
Location: Mountlake Terrace, WA
Posts: 2,139
Likes: 1,139
Liked 1,477 Times in 594 Posts
|
|
Thanks for the info Steve, but it seems like every time I try to read another article to finally get an accurate answer on the .308 v. 7.62 question, and if it is safe to use one in a firearm marked for the other, it reinforces one thought for me.
Get a 30-06.
Last edited by BaldEagle1313; 06-21-2014 at 03:17 PM.
Reason: proofread fail!
|
The Following 6 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 02:34 PM
|
![Jack Flash's Avatar](https://smith-wessonforum.com/image.php?u=115507&dateline=1244344617) |
SWCA Member
|
|
|
Join Date: May 2005
Location: Michigan
Posts: 9,335
Likes: 34,339
Liked 11,025 Times in 3,974 Posts
|
|
Quote:
Originally Posted by CoMF
piezo = crusher * ( 1 + ( crusher^2.2 )/30000 )
|
Let's see what the equation gives us for 50,000 CUP (50 ksi):
piezo = 50 * (1 + 50**2.2/30000) = 50(1.18222) = 59.111 ksi[/FONT]
So it looks like that gives reasonably close results to the OP's statement that 50,000 CUP is roughly 62,000 piezo.
__________________
You're shy a few manners.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 05:21 PM
|
Member
|
|
|
Join Date: Aug 2012
Posts: 1,494
Likes: 474
Liked 1,447 Times in 670 Posts
|
|
Quote:
Originally Posted by Jack Flash
Let's see what the equation gives us for 50,000 CUP (50 ksi):
piezo = 50 * (1 + 50**2.2/30000) = 50(1.18222) = 59.111 ksi
So it looks like that gives reasonably close results to the OP's statement that 50,000 CUP is roughly 62,000 piezo.
|
You're a better man than me. I tried testing the formula myself and felt like my head was going to explode when I attempted to solve the decimal exponent.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 10:41 PM
|
![Nightowl's Avatar](https://smith-wessonforum.com/image.php?u=110281&dateline=1249094042) |
SWCA Member
|
|
|
Join Date: Apr 2004
Location: Warrensburg, MO USA
Posts: 5,304
Likes: 2,925
Liked 3,423 Times in 1,736 Posts
|
|
LVsteve: Thanks for that article. I had always heard that the two measures were not convertible, but felt that was not really accurate. This is great information and I appreciate your posting it.
__________________
Richard Gillespie
FBINA 102
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 10:53 PM
|
US Veteran Absent Comrade
|
|
|
Join Date: Mar 2006
Location: Missouri
Posts: 3,939
Likes: 4,106
Liked 2,582 Times in 1,106 Posts
|
|
So, can I shoot 308 in my M1A?
__________________
Regards, Ron
USASA 1965/69
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:22 PM
|
Member
|
|
|
Join Date: Aug 2005
Location: Starkville, MS
Posts: 912
Likes: 135
Liked 233 Times in 106 Posts
|
|
I'll stick in my $0.02
Crushing copper pellets is peachy keen fine except we have moved on to the "Digital Age" and the transducer, which measures pressure can be hooked up to measure the peak pressure over time... And that's where things get interesting. The pressure peak may be so transient that the copper does not have "time" to sufficiently deform. And spikes like that can result in failure of components. So copper is out and digital is in. Learn to live with it and love it.. ![Cool](https://smith-wessonforum.com/images/smilies/cool.gif)
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:31 PM
|
US Veteran
|
|
|
Join Date: Oct 2012
Location: Tonopah, AZ
Posts: 3,285
Likes: 23,843
Liked 11,060 Times in 2,299 Posts
|
|
help Help my eyes have glazed over I can't see! Ahhhhhhhhh........Whew now where's that keyboard.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-21-2014, 11:48 PM
|
![DR505's Avatar](https://smith-wessonforum.com/image.php?u=154352&dateline=1398103371) |
US Veteran
|
|
|
Join Date: Jul 2009
Location: Idaho
Posts: 4,388
Likes: 3,375
Liked 8,474 Times in 2,310 Posts
|
|
I'm confused: between .308 and 7.62, which is a CTG?
__________________
No good deed goes unpunished.
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-22-2014, 01:33 AM
|
![LVSteve's Avatar](https://smith-wessonforum.com/image.php?u=119432&dateline=1275775928) |
Member
|
|
|
Join Date: Feb 2005
Location: Lost Wages, NV
Posts: 20,465
Likes: 25,275
Liked 30,094 Times in 11,202 Posts
|
|
Quote:
Originally Posted by RonJ
So, can I shoot 308 in my M1A?
|
If you are talking factory ammo, it depends on the pressure curve of the powder. I've shot ammo Remington green box FMJ marked .308 from a FAL with no problems. Red-X marked Winchester does not work well at all as it has too slow a powder. Even the adjustable gas system on the FAL cannot cope.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-22-2014, 11:15 PM
|
Banned
|
|
|
Join Date: Sep 2011
Posts: 1,759
Likes: 613
Liked 1,190 Times in 626 Posts
|
|
Quote:
Originally Posted by LVSteve
If you are talking factory ammo, it depends on the pressure curve of the powder. I've shot ammo Remington green box FMJ marked .308 from a FAL with no problems. Red-X marked Winchester does not work well at all as it has too slow a powder. Even the adjustable gas system on the FAL cannot cope.
|
I feel you are very on target with this. (Pun intended!)
From what I have seen recently, the chrono tells us that NATO 7.62 and a variety of 308 hunting ammo were not far off of each other; within 100-150FPS. As to what I have seen in hit power on the plates, all things being equal, they stack up pretty equally in the amount of penetration, the amount of swin the target does, etc.
Yet, with the rifle we tested the ammo on last, the Winchester XP did not cycle the last round and lock the bolt, but NATO ammo, and cheap Wolf ammo would. But the chrono said the Winchester was a little faster. I put this down to powder burn characteristics. Everything else was identical.
Good point!!
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-22-2014, 11:45 PM
|
![Straightshooter2's Avatar](https://smith-wessonforum.com/image.php?u=187169&dateline=1318883827) |
US Veteran
|
|
|
Join Date: Oct 2011
Location: South of Gritville
Posts: 2,580
Likes: 1,113
Liked 2,547 Times in 1,006 Posts
|
|
Quote:
Originally Posted by BaldEagle1313
Thanks for the info Steve, but it seems like every time I try to read another article to finally get an accurate answer on the .308 v. 7.62 question, and if it is safe to use one in a firearm marked for the other, it reinforces one thought for me.
Get a 30-06.
|
^^^^^^^^
This.
CW
__________________
μολὼν λαβέ
|
The Following 2 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-23-2014, 11:18 AM
|
Member
|
|
|
Join Date: Nov 2006
Posts: 2,690
Likes: 6
Liked 351 Times in 243 Posts
|
|
It's been awhile since I researched this, and my mind is still in a blur, but this is what I seem to recall...
The .308 and .223 were civilian versions of their respective military counterparts. Even though their pressures look different, even if measured in the same scale, they are not. The military specifications require the pressure to read at the case mouth instead of the back of the case like SAAMI does. When SAAMI set their specifications it was based off of military ammunition, that's the way SAAMI works.
The difference between rifles marked in the civilian calibers, .308 or .223, and the military calibers isn't the ammunition they shoot, it's a slight difference in the lead of the firearms chamber. The respective ammunition is similar and completely interchangeable.
Last edited by Jellybean; 06-23-2014 at 11:20 AM.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 02:14 AM
|
![LVSteve's Avatar](https://smith-wessonforum.com/image.php?u=119432&dateline=1275775928) |
Member
|
|
|
Join Date: Feb 2005
Location: Lost Wages, NV
Posts: 20,465
Likes: 25,275
Liked 30,094 Times in 11,202 Posts
|
|
Quote:
Originally Posted by Jellybean
It's been awhile since I researched this, and my mind is still in a blur, but this is what I seem to recall...
The .308 and .223 were civilian versions of their respective military counterparts. Even though their pressures look different, even if measured in the same scale, they are not. The military specifications require the pressure to read at the case mouth instead of the back of the case like SAAMI does. When SAAMI set their specifications it was based off of military ammunition, that's the way SAAMI works.
The difference between rifles marked in the civilian calibers, .308 or .223, and the military calibers isn't the ammunition they shoot, it's a slight difference in the lead of the firearms chamber. The respective ammunition is similar and completely interchangeable.
|
From my research sources, the the chamber leade/freebore spec for 308 Win and 7.62 NATO is the same, but 7.62 NATO has larger allowable headspace with the shoulder area of the chamber being about 0.013 longer. As stated before, this is a nod towards keeping a hot and dirty weapon running in combat. I have a reference .308 Winchester vs. 7.62x51mm NATO 7.62 NATO ammo is happy in the extra space due to its thicker case web. The same article claims that the CUP/PSI confusion was actually started by the Army, which if true is pretty darned funny. ![Big Grin](https://smith-wessonforum.com/images/smilies/biggrin.gif)
There is a difference in the leade and free bore between 223 Remington and 5.56 NATO. 5.56 NATO is somewhat longer, so it gets away with using the long 77gr bullet without overpressure. Scroll down this page for the precise details. http://www.frfrogspad.com/ar.htm
After that we get into the Wylde and Noveske chambers which attempt to allow for long bullets and 5.56 NATO compatibility while retaining 223 Remington accuracy.
From all the references I can find .223 Remington and 5.56 NATO cases are identical. The Wikipedia article claims that NATO and US milspec pressures for 5.56 are equivalent and the difference in numbers is due to the US military allowing the use of the SAAMI measurement protocol. I can buy into that to some degree but others do not. Indeed, the latest and greatest Mk 262 77gr rather fast for a round that is supposed to be running at SAAMI equivalent pressures, and this tester even says "NATO pressure". MK262 clone 77Grain 5.56 load problems / updated OCW tests It has been acknowledged that the gas port pressure with this round is way higher than normal. How much of that is "boost" and how much is powder burn rate I cannot say. Special powder you cannot buy at Midway is suspected.
The US armed forces do play fast and loose when it comes to pressures, especially with special weapons like sniper rifles. The latest 300 Win Mag round uses a special brew that is well past SAAMI specs. This was done so that the round would not appear too inferior to the .338 Lapua. ![Wink](https://smith-wessonforum.com/images/smilies/wink.gif) They get away with it by using custom built rifles with new cases and load lengths matched to the gun. Even so I feel it would be prudent to put a "useful life" limit on such a tweaked weapon.
Last edited by LVSteve; 06-24-2014 at 02:17 AM.
|
The Following 3 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 08:06 AM
|
![sipowicz's Avatar](https://smith-wessonforum.com/image.php?u=122512&dateline=1248362249) |
Member
|
|
|
Join Date: Aug 2005
Location: Gun lovin\' Hollywood Ca.
Posts: 10,234
Likes: 7,741
Liked 18,710 Times in 3,792 Posts
|
|
I just measured my inseam and it came out to 3 pianos from the 50s.
__________________
Thirty characters. Exactly...
|
The Following 3 Users Like Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 08:27 AM
|
Member
|
|
|
Join Date: Apr 2013
Location: Sleeping under a tree.
Posts: 81
Likes: 18
Liked 57 Times in 23 Posts
|
|
You guys have just given me a belly full of laughs.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 09:17 AM
|
Member
|
|
|
Join Date: Apr 2014
Posts: 195
Likes: 621
Liked 202 Times in 83 Posts
|
|
Quote:
Originally Posted by RonJ
So, can I shoot 308 in my M1A?
|
I do it regularly. Nothing over 168gr. though as I value my op-rod.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 11:55 AM
|
Member
|
|
|
Join Date: Nov 2006
Posts: 2,690
Likes: 6
Liked 351 Times in 243 Posts
|
|
Steve, I'm afraid your links are no more credible than the rag you mentioned in your first post. I didn't read all of them, mostly because there were so many mistakes it wasn't worth continuing.
I don't consider anything on the internet as "fact" unless it's from a reputable source. This isn't either, but I am going to try to verify the information in post nine on the chamber dimensions as it appears your source on the "headspace" issue is pretty wrong.
7.62 x 51 mm and .308 winchester - M14 Forum
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 12:17 PM
|
Banned
|
|
|
Join Date: Dec 2013
Posts: 248
Likes: 366
Liked 377 Times in 104 Posts
|
|
The 223/556 argument never ends. I've heard "experts" say it's OK to shoot 556 out of a 223-stamped gun while others say you shouldn't.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 01:17 PM
|
Member
|
|
|
Join Date: Oct 2005
Location: A Burb of the Burgh
Posts: 14,823
Likes: 1,727
Liked 19,944 Times in 8,819 Posts
|
|
The folks at CZ ..... say that their .223 527s are good to go with 5.56.....
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 02:00 PM
|
![Alpo's Avatar](https://smith-wessonforum.com/image.php?u=127063&dateline=1329766462) |
Member
|
|
|
Join Date: Sep 2006
Location: N/W Florida
Posts: 5,694
Likes: 2,450
Liked 6,256 Times in 2,442 Posts
|
|
I tend to ask the maker.
Springfield said I could use 7.62 or 308 in my M1A.
Ruger said I could use 223 or 5.56 in my Mini 14.
Ruger also said to only use 223 in my #1.
__________________
I always take precautions
|
The Following User Likes This Post:
|
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-24-2014, 09:27 PM
|
![LVSteve's Avatar](https://smith-wessonforum.com/image.php?u=119432&dateline=1275775928) |
Member
|
|
|
Join Date: Feb 2005
Location: Lost Wages, NV
Posts: 20,465
Likes: 25,275
Liked 30,094 Times in 11,202 Posts
|
|
Quote:
Originally Posted by Jellybean
Steve, I'm afraid your links are no more credible than the rag you mentioned in your first post. I didn't read all of them, mostly because there were so many mistakes it wasn't worth continuing.
I don't consider anything on the internet as "fact" unless it's from a reputable source. This isn't either, but I am going to try to verify the information in post nine on the chamber dimensions as it appears your source on the "headspace" issue is pretty wrong.
7.62 x 51 mm and .308 winchester - M14 Forum
|
I'm not seeing any difference the headspace data in your link and the one I quoted. ![Confused](https://smith-wessonforum.com/images/smilies/confused.gif) ![Confused](https://smith-wessonforum.com/images/smilies/confused.gif)
As for confusion over pressures, I see much of it on the M14 forum and in that thread. Consider the factors for confusion:
1) NATO/CIP have their test standards and the answers are in PSI.
2) SAAMI have a different test standard and the answers are also in PSI, but will be slightly different from the NATO/CIP values for the same round.
3) Back in the day the US used CUP to judge chamber pressure and it gives readings in the same order of magnitude as PSI measurements with the same ammo, but CUP readings are different enough to cause problems.
4) Add poor attention to detail, lack of the appreciation for scientific units leading to careless mixing of PSI and CUP, and throw in a liberal dose of poor reading comprehension (ain't got no time fo dat ![Big Grin](https://smith-wessonforum.com/images/smilies/biggrin.gif) ) and guess what you get?
Last edited by LVSteve; 06-24-2014 at 11:48 PM.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-25-2014, 07:35 AM
|
![martybee's Avatar](https://smith-wessonforum.com/image.php?u=237109&dateline=1404526671) |
Member
|
|
|
Join Date: Nov 2013
Location: STL Area: Belleville, IL
Posts: 1,135
Likes: 2,446
Liked 777 Times in 407 Posts
|
|
Quote:
Originally Posted by coltle6920
I'll just pretend I understand what you're talking about.I'm still awed by the fact that socks can go on either foot.
|
And I too am awed by that, and marvel at the fact that "Tube Socks" need no orientation of the heel to be addressed when
pulling them on!
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-25-2014, 08:00 AM
|
![johngalt's Avatar](https://smith-wessonforum.com/image.php?u=147045&dateline=1638665186) |
Member
|
|
|
Join Date: Feb 2007
Location: St. Paul (smokey!) MN
Posts: 5,405
Likes: 1,545
Liked 6,849 Times in 2,618 Posts
|
|
The .223 vs .556 can get real confusing with its labeling. Some ammo is labeled both (.223/5.56). Which is it? Some just .223, other just 5.56. I've been told some ammo labeled .223 is really 5.56. Is it really?
In any case, I've shot it all in my .223 M70, my dad has shot it in his ruger #1. It has all been fine. I suspect the most important factor is the real heavy bullets may not stabilize due to the slower twist rate. 62 gr is the heaviest I've used.
I have a hard time believing that a m70 or #1 chamber is weaker than an ar15 chamber.
__________________
Common sense isn't so common.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-25-2014, 09:25 AM
|
![SMSgt's Avatar](https://smith-wessonforum.com/image.php?u=167160&dateline=1711289006) |
Member
|
|
|
Join Date: Jul 2010
Location: Florida
Posts: 6,751
Likes: 3,505
Liked 9,488 Times in 3,573 Posts
|
|
Quote:
Originally Posted by coltle6920
I'll just pretend I understand what you're talking about.I'm still awed by the fact that socks can go on either foot.
|
Post of the week!
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-25-2014, 09:34 AM
|
![SMSgt's Avatar](https://smith-wessonforum.com/image.php?u=167160&dateline=1711289006) |
Member
|
|
|
Join Date: Jul 2010
Location: Florida
Posts: 6,751
Likes: 3,505
Liked 9,488 Times in 3,573 Posts
|
|
Quote:
Originally Posted by johngalt
The .223 vs .556 can get real confusing with its labeling. Some ammo is labeled both (.223/5.56). Which is it? Some just .223, other just 5.56. I've been told some ammo labeled .223 is really 5.56. Is it really?
In any case, I've shot it all in my .223 M70, my dad has shot it in his ruger #1. It has all been fine. I suspect the most important factor is the real heavy bullets may not stabilize due to the slower twist rate. 62 gr is the heaviest I've used.
I have a hard time believing that a m70 or #1 chamber is weaker than an ar15 chamber.
|
No differences (okay a very, very slight difference in capacity that won't matter) in the cases. The differences is the military rounds are typically longer than sporting .223s, so 5.56-chambered rifles have a longer throat than sporting .223 rifles. A 5.56 round may cause the bullet to engage the rifling in a .223 chambered rifle, and thus raising pressures. If you chamber a longer 5.56 round and after ejecting it find no rifling marks on the bullet, your throat is probably long enough.
Secondly, military rounds are hotter than sporting .223s. Will sporting rifles handle the higher pressures? Maybe, maybe not.
I've noticed most ARs are compatible with both rounds, but a few are .223 only chambered. Why a box of ammo would be marked .223/5.56 is beyond me and sets the stage for a possible accident.
|
![Old](https://smith-wessonforum.com/images/blue_style/statusicon/post_old.gif)
06-25-2014, 09:45 PM
|
Member
|
|
|
Join Date: Aug 2009
Posts: 1,145
Likes: 37,463
Liked 953 Times in 509 Posts
|
|
I would suspect that ammo marked 223/556 is considered by it's maker to be safe to use regardless of the chambering specs and throat dimensions. I have used both interchangeably for years with no difficulty in quite a few different rifles.
Military chambers are often a little generous (to allow for dirty ammo) and may well have a longer throat but I really doubt there is a significant difference between commercial and military loads with the same weight bullets. I can see where a tight, match spec chamber in 223 could have problems with mil spec ammo but it could very well have trouble with some 223 commercial stuff as well. As more than one poster already mentioned, pressure measuring methods vary and it's not easy to relate one system to another.
|
The Following User Likes This Post:
|
|
![Reply](https://smith-wessonforum.com/images/blue_style/buttons/reply.gif) |
|
Posting Rules
|
|
|
|
|