M&P10 .308 Ammo reload question

[ksgries]

Do any of you guys reload your own ammo?

If you do which do you reload .308 or 7.62x51?

I've read that once you start using reloaded rounds you should only use the ones that it is specifically cambered for. To my understanding I could use factory .308 or 7.62x51 all I want, but when I use reloaded rounds it becomes a problem.

I don't want anything going horribly wrong. This is the first gone my dad and I have had that could use two different calibers.

And yes I know that .308 and 7.62x51 only have a extremely miniscule difference.

 

[Vision Remodeling]

I copy and pasted this for you, I was reading it just a few minutes ago.

The difference between .308 and 7.62 is chamber size, slight pressure differences due to powder burn rates, not external case size. Both cases will have the same external dimensions while the .308 has a pressure of 60Kish PSI vice 50-55 CUP psi for NATO**. NOTE: This is not the same as 5.56/.223 rule of thumb. The NATO chambers have greater tolerances to help with reliable functioning of military ammo. The NATO chamber is ever so slightly longer at .013". This is significant in that for reloading purposes, 308 brass will stretch more in a military chamber upon firing, thereby reducing the life of the brass and possibly promoting case head separation. But that additional chamber length will allow a round to chamber in an incredibly dirty weapon, which is a requirement for military applications. Also be aware this is why mil NATO brass is thicker vice 308 commercial brass. You will also see this "thicker brass fact" posted about 5.56/.223 brass which is a fallacy.

**As a side note the reason the pressure issue is confusing is because the military measured 7.62 NATO chamber pressure (PSI) via CUP (in the 40s) vice the normal commercial rating of PSI measured (now) with electronic means. You will see many cling to the 50-55K PSI figure for 7.62 Nato becuase that is what the old Army TMs have in them. Since there is no conversion for the CUP measurement to the newer electronic measured PSI, they are two different numbers i.e no direct comparison. Many people will assume the CUP PSI is the same as SAAMI/Commercial PSI. It is not. Commercial PSI is derived from the direct pressure in the chamber through electronic means (piezo transducer or strain gauges). CUP is a crush measurement of a copper slug that has been fired, again not the same test.

That means any newer weapon will be able to fire 308 Commercial ammo as manfs would not let them out the door if they could not, due to liability. Don't believe me, run the numbers/powders in any internal ballistics calculator and they will all be close to the 60K mark. BTW the proof load for the 308 commercial is 75K PSI, so don't worry about the 60K.

Here a good discussion with some testing not myth about how the pressures are basically the same despite the wives tales

7.62 X 51 cartridge vs. .308 Winchester: the differences! - M14 Forum

7.62x51... the real facts! - M14 Forum




GO GAGE CHAMBER SPEC INFORMATION (TOLERANCES FOR GOOD-TO-GO CHAMBERS)
•AR-10 NATO – 1.633-1.638 (stainless steel, chrome moly, and chrome lined barrels) "

308 Winchester (SAAMI) Headspace
GO - 1.6300"
NOGO - 1.6340"
FIELD - 1.6380"

7.62 NATO (Military) Headspace
GO - 1.6350"
NOGO - 1.6405"
FIELD - 1.6455"

Note that the military chamber would fail a NO GO check with a SAAMI gauge, but pass a FIELD check using the proper military gauges.

 

[ksgries]

Seems like the smart thing would be to stay with 7.63x51 due to the fact that they stretch less.

 

[ksgries]

Does anyone know where I can find dies for 7.62x51?(preferably carbide)
I cant find any, only .308.

 

[Autococker07]

Same dies,

But don't waste your money on carbide, you need to lube ANY bottleneck rifle brass when reloading, carbide works with straight wall brass because there is less tension upon resizing.

You can neck size if you are shooting through the same chamber, but will need to full length size for ammo that will fit all chambers. Also if neck sizing about every three or four firings you will have to full length size again.... as the brass stretches out.

Another thing to consider is that nato brass has less internal capacity than commercial.

 

[ksgries]

But don't waste your money on carbide, you need to lube ANY bottleneck rifle brass when reloading, carbide works with straight wall brass because there is less tension upon resizing.

You can neck size if you are shooting through the same chamber, but will need to full length size for ammo that will fit all chambers. Also if neck sizing about every three or four firings you will have to full length size again.... as the brass stretches out.

Another thing to consider is that nato brass has less internal capacity than commercial.

Hmm thanks for that bit of info. Not like I can find any dies for 7.62x51 anyway and even the .308 dies are all sold out.

 

[cb4017]

Buy a quality .308 full length die set. I have an RCBS set that I've used for over 30 years to load for various .308 and 7.62 rifles with no problems, including my M&P 10.

I suggest you get a good reloading manual with a how-to section.

Good luck.

 

[Fishinfool]

7.62x51 NATO and 308 Winchester reloading dies are the same thing, that's why you cant find 7.62x51 dies listed. You can reload brass marked as either without issue, other than you might find some NATO brass that has crimped primers. And NATO brass may be slightly thicker on the inside, which means slightly less case capacity, which means you may have to reduce your powder charge slightly when loading max. loads.

You can experiment with neck sizing only, as that will lessen case stretch, and prolong brass life, but that may come with reliability issues in a semi-auto. I full length resize for my semi's, trim when needed, and accept slightly less case life in exchange for reliability.

In short, the numbers 7.62 is metric for 30 cal., and 51 is the case length in millimeters - A 308 Winchester.

Reading a good reloading manual like Speer or Lyman will answer a lot of your questions, and clarify things for you.

Larry

 

[loc n load]

308 /7.62

Not to be redundant...but what post #7,8,9 said.....I have been reloading 7.62 /308 for decades....have shot thousands of my reloads in precision bolt guns, H&k 91's and clones, FAl's, AR-10's, M1A's, bone stock 308 bolt guns and have never had any issues.....
Reloading manuals and text's are a "must have".....the 308/7.62 is one of the most reloaded rifle rounds out there, and thousands of shooters reload for it.

 

[ksgries]

Thanks for all that info guys. I was under the impression that I couldn't use .308 dies for 7.62. Glad I got that all cleared up.

Ordering myself some .308 dies soon.

 

[unknwn]

There are RCBS .308 small base die sets available at Midway USA .
The small base sizer die is a must for reliable reloads in AR-type semi-auto rifles.
I had a set of standard .308 full length RCBS dies left to me by my brother when he loaded for his M14 and found that the cases sized using them wouldn't fit in a guage produced to check reloads for use in AR type gas-gun chambers.
Also, be careful about powder selection for gas-gun usage .
Many manuals will list powders for use in .308 Winchester that are too fast burning for the M&P10 (amongst other AR-style .308 rifles).
The Sierra reloading manual devotes several pages to the particulars of reloading for an AR type of gas gun.
Check out the JP case guage. Without one you take too many chances with out of spec resized cases for these AR-type .308 rifles.

 

[ksgries]

There are RCBS .308 small base die sets available at Midway USA .
The small base sizer die is a must for reliable reloads in AR-type semi-auto rifles.
I had a set of standard .308 full length RCBS dies left to me by my brother when he loaded for his M14 and found that the cases sized using them wouldn't fit in a guage produced to check reloads for use in AR type gas-gun chambers.
Also, be careful about powder selection for gas-gun usage .
Many manuals will list powders for use in .308 Winchester that are too fast burning for the M&P10 (amongst other AR-style .308 rifles).
The Sierra reloading manual devotes several pages to the particulars of reloading for an AR type of gas gun.
Check out the JP case guage. Without one you take too many chances with out of spec resized cases for these AR-type .308 rifles.

Thanks ill check out that manual

 

[Bat Guano]

I use military brass with small base .308 dies in my M1A and trim to slightly less than max case length in a Dillon sizer/trimmer. I check each case after trimming and also loaded rounds after loading. Zero issues.

(I swage military primer pockets with a Dillon primer pocket swager as well.)

Zero problems in the M1A and M1 using this system.

Thinking about an M&P 10. I wouldn't expect it to act any differently. The key is precision and consistency.