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Old 10-31-2009, 10:18 AM
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Question Chamber pressure and primer signs

There are many knowledgeable reloaders on this forum. What is your response to this situation. The same standard large rifle primers are used in the following cartridges: .30-30 Win, .270 Win, .30-06, 7mm Rem Mag, and .45-70 Gov. Numerous reloading books, articles, and internet documents warn of "signs of high chamber pressure", "flatened primers", and "primer flow".

Without quoting numbers and pressure units, the ascending chamber pressure, lowest to highest, for the above cartridges would be: .45-70, .30-30, .30-06, 7 mm Mag, and .270 (the data I looked at gave .270 Win higher values than 7 mm Rem Mag).

My discussion point: How does primer condition give pressure warnings for .30-30 and .45-70 loads when .30-30 chamber pressure is ~1/2 and .45-70 is ~1/3 that of 7 mm Mag or .270 Win? I ask this in the context of a new reloader trying to comprehend the wealth of information available in a few keyboard clicks, while trying to make "safe" reloads. I consider myself informed about reloading, but not an expert.
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Old 10-31-2009, 10:56 AM
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Am relying on measured velocities from chronograph, in conjunction with current published manuals, while taking into account the specific bullet, brass and primer.

By the time you get primer flow, flattened/pierced/blown primers etc, ya are likely loading too hot already.

Imo, handloading towards the upper end without a chronograph is ill advised. A Beta F1 master is cheap assurance.

Certainly others may have different opinions.
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Old 10-31-2009, 11:03 AM
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Quote:
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My discussion point: How does primer condition give pressure warnings for .30-30 and .45-70 loads when .30-30 chamber pressure is ~1/2 and .45-70 is ~1/3 that of 7 mm Mag or .270 Win? I ask this in the context of a new reloader trying to comprehend the wealth of information available in a few keyboard clicks, while trying to make "safe" reloads. I consider myself informed about reloading, but not an expert.
The appearance of the primer will allow you to compare your handloads to factory ammo that used the same brand primer. Primer condition alone is not that great, at telling you how safe your loads are. Especially loading the calibers you mention. Primer appearance in a 7 mag. load could be idendical to that in your 30-30 loads. This could mean some awfully wimpy 7 mag. loads or some dangerous .30-30 loads, even though the primers looked the same.

Like I said, use primer appearance to compare to known, factory loads.
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Old 10-31-2009, 11:22 AM
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This is a great question. The answer is that primer flattening and flow are not useful indicators for assessing chamber pressure in low pressure rounds like .45-70 and .30-30. These changes occur at a given pressure that's independent of which cartridge you're using. For example, if primers flow at 70,000 psi, that's too high a pressure for a .30-06, but a good rifle would probably contain it. A trapdoor Springfield in .45-70 would surely blow up before reaching that pressure. The bottom line is that you can't take the absence of these primer signs as an indication that your load is OK. Another factor is that different primer brands have different degrees of cup hardness, which affects the pressure at which these signs appear.

This has been discussed before with regard to handgun cartridges. A good example would be the .44 Special, which has a SAAMI maximum pressure of around 15,000 psi. If your load developed 25,000 psi, you'd have no way of knowing it from primer condition. Such a load might be OK in a modern N-frame S&W, but I sure wouldn't want to use it in a Triple Lock with its non-hardened steel cylinder.

Flattened primers, especially with Federal primers, occur routinely in Magnum handgun cartridges and are not necessarily a sign of high pressure.
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Old 10-31-2009, 11:45 AM
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Quote:
I ask this in the context of a new reloader trying to comprehend the wealth of information available in a few keyboard clicks, while trying to make "safe" reloads. I consider myself informed about reloading, but not an expert.
The only way to be sure the load is safe is if you find reputable published data in at least two manuals, or if you personally have run the load through a pressure test barrel.

You have brought up one of the ugly myths about developing loads. In truth, pressure signs are often unreliable!
Older guns with low pressure load specs may give the first pressure sign when the topstrap hits the ceiling.
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Old 10-31-2009, 12:51 PM
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All of the above info is good. Don't forget that a gun with even a little excess headspace can give high pressure signs with your primers, while in fact there aren't any pressure issues at all. Variations in primer cup hardness can also give different appearences in the fired primer's appearence.

Trying to read pessure without a chrono and published data, or a pressure barrel, is futile at best, and can be dangerous at the worst. In days long gone by, they didn't have all the chrono's and pressure barrels etc., that are available today, and they tried to figure pressure the best they could, even though most of it has been proven totally unreliable today.
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Old 10-31-2009, 12:51 PM
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Bob; Rule number one....follow your reloading manual for the type and caliber of cartridge and firearm you are loading for! Rule number two....Never fire any gun that you are unsure of...be it for age or mechanical reliability. Rule number three.... Nothing in shooting is a "constant" so, you have to be on the lookout for "all" the signs of high pressure and make a judgement.

Pressure developed by the ignition of a powder charge in a cartridge, when the cartridge is in the chamber of the firearm can only go in a few different directions. Pressure is relieved by the bullet exiting the cartridge and traveling down the bore. The bore diameter only allows for so much pressure to be relieved...the technical term is "bore capacity" or, the ability of the capacity of the bore to burn so much powder efficiently, and relieve pressure so as not to cause a high pressure condition. If you reach the "capacity" of the bore to do that, the excess pressure developed by the overload of powder will seek the path of least resistance. If your cartridges are in good shape, the next path would be the primer flash hole, primer pocket, and the primer. The primer will "give", be pushed out of the primer pocket and be forced against the bolt face, flattening the primer, and release excess pressure, but, only to a certain point. From that point, if the bullet and primer can not compensate for the over pressure condition, the case takes a hit....this is exemplified by the case sticking upon extraction, case head seperation, and case head swelling that sometimes requires prying the case head out of the bolt face, etc. After that point, pressure is so excessive that the excess pressure can do severe damage to the firearm, up to and including a blow up!

Most modern rifles have a "pressure relief port" built into the design, but, that does not mean that you can exceed the safe maximum operating pressure of the firearm, or, that it will save the firearm from damage under a given set of circumstances.

In closing, firearms will punch paper and kill effectively without "maximum loads". A load that is accurate, and carries enough power for the intended purpose is all that is needed. In my 44 Magnums I load a 250 grain Keith at 1000 fps for defense and deer hunting. That is more like a 44 special +P load, but it does the job well, is easy to shoot, and is accurate. Same goes for my 444 Marlin levergun. I use a 300 grain bullet at 1850 fps for deer hunting (the cartridge is capable of driving that same bullet at well over 2000 fps), the load is accurate, easy on the gun, easy on me, and very hard on the deer! If you keep everything in perspective you will realize that loading to the max or higher does nothing for the longevity of the firearm, accuracy, your physical well being, or your pocketbook. If a bigger/faster/ more powerful is needed there is always a firearm out there to fill that spot.
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Old 10-31-2009, 09:19 PM
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Thumbs up Can this be a sticky?

I believe this thread has great information for the many "new" reloaders that may follow an incorrect path when starting to reload.

A big THANK YOU to all who contributed to this discussion.
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Old 11-01-2009, 08:16 AM
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Quote:
Originally Posted by flat top View Post
If you keep everything in perspective you will realize that loading to the max or higher does nothing for the longevity of the firearm, accuracy, your physical well being, or your pocketbook. If a bigger/faster/ more powerful is needed there is always a firearm out there to fill that spot.
Very well said.
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Old 11-01-2009, 08:46 AM
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I have been reloading for over 35 years and all of the game that I have taken has been with handloads. I am conservative and tend to stick with loads that are on the moderate side. Two reloading books that I have found very useful over the years are Ken Waters' "Pet Loads" and Midway's " caliber specific spiral bound "Load Books". Pet Loads is very comprehensive covering about any cartridge you'd want to reload, Mr. Waters has been a reloading authority for many years and I have always found his advise to be based on actual field/range experience and sound judgement. I like the midway books because the list most all the lead and jacketed bullets that you'd probably want to load with the exception of the premium performance types. Pressure is listed for the loads and a green,yellow,red color coding helps focus the reloader's attention where a particular load is apt to fall as far as pressure is concerned. As I said at the outset, I start rather low not necessarily with the lowest load listed and when the groups obtained with the load are satisfactory then I go no further. In the three cartridges that I hunt with .257 Roberts, .35 Whelen and .338 Winchester Magnum, moderate loads with bullets constructed for the game intended have never failed to put meat on the table.
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Old 11-01-2009, 10:18 AM
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When I first got into reloading, some 40+ years ago, I was guilty of pursuing those hot high pressure loads that some seem to strive for. After a lifetime of experience (gunsmithing, competitive shooting, and hunting), and coming in contact with those that had "realistic" veiws (like Marksman) of ballistics, firearm construction, and what it takes to bring down game, and seeing both handgun and rifle "blow ups", and the damage they cause not only to the gun, but to the shooter, my attitudes toward those high pressure loadings changed. Many would not think that a 45 ACP would be a very good handgun for deer hunting, but, I managed to take two deer with mine, and it did a fine job! A buddy of mine and fellow competitor used a 44 Special as his deer hunting handgun and had many successful hunts. For personal protection or game up to deer size, not much more is needed, and neither he nor I used "over the top" high pressure loads to get the job done. In my opinion, a load that is suitable for the job at hand...the correct bullet....and the ability to place the bullet in the kill zone or X-ring is all that is needed. No matter how fast a bullet is driven, if it does not hit the "spot" it does no good! Accuracy is the key to success be it paper punching or hunting, and that is what reloading allows the shooter.....an affordable means of custom tailoring accurate ammunition for a specific firearm and purpose.
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Old 11-01-2009, 10:33 AM
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Quote:
Originally Posted by Engineer1911 View Post
My discussion point: How does primer condition give pressure warnings for .30-30 and .45-70 loads when .30-30 chamber pressure is ~1/2 and .45-70 is ~1/3 that of 7 mm Mag or .270 Win?
Simple - it doesn't. It always pays to ask questions, but don't underestimate the power of your own mind, particularly if you are in the habit of using it.
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Old 11-01-2009, 10:40 PM
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This post is not intended to flame anyone, especially flat top since he and I are friends off forum. I offer the following just to present an opposing view here, but one I have heard many times in my life, and one with which I agree.

I guess I am the minority here maybe, but if I buy a .44 magnum, you can bet I'll be using magnum loads in it. It doesn't hurt a darn thing, and I take exception to the claims to the contrary. Sure they will wear the gun more quickly than a mild load, but few of us ever fire enough rounds in a lifetime with one gun, to wear it out. Why buy a bigger gun, then nueter it with weaker loads than it was designed for?

I use mid-range loads all the time, but when hunting, I use full on loads. If you can't shoot accurately with your gun and it's factory designated load, then you shouldn't even consider taking it to the woods to kill something that you may only wound instead due to poor shooting.

I have no quarrel with those who water down their loads to hunt, but I do get miffed when someone tries to tell me that I am doing damage to my gun by using the load it was designed for, or that it is more than needed. If we followed that logic, we would all be using a sharpened stick fired from a longbow, since it will kill a deer just fine if you stick it in the right place.

This is America, and freedom to choose and use what we want is what makes this country so great.
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Old 11-02-2009, 01:02 AM
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Originally Posted by Gun 4 Fun View Post
This post is not intended to flame anyone, especially flat top since he and I are friends off forum. I offer the following just to present an opposing view here, but one I have heard many times in my life, and one with which I agree.

I guess I am the minority here maybe, but if I buy a .44 magnum, you can bet I'll be using magnum loads in it. It doesn't hurt a darn thing, and I take exception to the claims to the contrary. Sure they will wear the gun more quickly than a mild load, but few of us ever fire enough rounds in a lifetime with one gun, to wear it out. Why buy a bigger gun, then nueter it with weaker loads than it was designed for?

I use mid-range loads all the time, but when hunting, I use full on loads. If you can't shoot accurately with your gun and it's factory designated load, then you shouldn't even consider taking it to the woods to kill something that you may only wound instead due to poor shooting.

I have no quarrel with those who water down their loads to hunt, but I do get miffed when someone tries to tell me that I am doing damage to my gun by using the load it was designed for, or that it is more than needed. If we followed that logic, we would all be using a sharpened stick fired from a longbow, since it will kill a deer just fine if you stick it in the right place.

This is America, and freedom to choose and use what we want is what makes this country so great.

A VERY BIG DITTO TO THIS!!!!!!!

I use reduced loads for plinking and such.I used to shoot thousands of rounds from 44 magnums every year and less stress was a concern of mine.

I don't want to get into a debate about cast vs jacketed or heavy bullet vs light but I definately use full loads when serious purpose is in mind.When I carry a 357 mag snubby concealed,it is actually a 357 magnum minus the reduction due to the shorter barrel.When I carry a 44 magnum,it is a 44 magnum.

When one makes the argument that X load is good enough,it can be carried to extremes.A 7mm Mauser has killed everything that walks the planet(including elephant and cape buffalo) but I have never understood the concept of only using "just enough".

The numbers and letters rollmarked on a barrel are meaningless if one deliberately loads down.If one chooses to load his 44 magnum as a 44 special,that's perfectly okay but those who load it as originally conceived get a bit tired of hearing talk about the gun blowing up when so used or the power being superficial.
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Old 11-02-2009, 07:32 AM
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I've found that in centerfire revolvers, often "sticky extraction" is a better sign of high pressure than the condition of the primers. Of, course thats from past experiance for the most part because as already mentioned, if you want more, get a bigger gun. Although I did have 45 Auto Rim madness a while ago!
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Old 11-02-2009, 01:22 PM
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Originally Posted by Vulcan Bob View Post
I've found that in centerfire revolvers, often "sticky extraction" is a better sign of high pressure than the condition of the primers. Of, course thats from past experiance for the most part because as already mentioned, if you want more, get a bigger gun. Although I did have 45 Auto Rim madness a while ago!
It's not really madness Bob.

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Old 11-02-2009, 02:44 PM
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Handloader December 2009 No. 263 (Page Numbers 10 & 11) A Reloading Warning by Dr. Don Heath, D.Sc, Technical Support, Norma Precession AB

Worth reading: “68000 PSI no visible pressure signs case and primer” – “81000 PSI only a little stickiness when I opened the bolt”
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