Springfield Armory M1A1

jprice846

What is the ideal ammunition for an M1A1 Scout? I bought my son one of these and get get a good read on whether there's a correct size between 308 Win., or 7.62 51 or 7.62 54.

Anyone have a suggestion?

Thanks

jtmarine0831

Oh no Not th 7.62x 54! It won't even chamber! 7.62x51mm is the NATO designation for the 308Winchester! The 7.62x 54R is the round most common for the Mosin-Nagant and SVD rifles. 308Win and 7.62x51mm are externally deminsioned the same, but have some very important differences. The 7.62x51 has thicker case walls to handle the abuse from full-autos and open-bolt operating machine guns. The thicker case wall are fine but present a challenge to the hand loader because load data for commercial brass is to much for Mil-spec brass. Another big kicker is primers. The 7.62NATO has a thicker primer cup due to most Mil-spec weapons utilizing a free-floating firing pin which can cause a slam fire. Using 308Win. in a rifle such as an M1A/M14 should be done with caution. If you use 308Win. in your M1A use only name brand ammo such as Remington and Winchester, cause their primers are more suitable, but still not as good as mil-spec.


Here is a link that better describes what I am trying to say!

http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

http://www.exteriorballistics.com/featured/index.cfm

Wolf.

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This was a very interesting explanation that you gave. It cleared up several questions that have kept the mice busy spinning the exercise wheels of my mind.

I have a question, however:
Why should the ammo make a difference with the commercially manufactured M1A1 Scout rifle?

With this weapon being produced primarily for the civilian market, one would think that the manufacturer (Springfield?) would build the weapon without the floating firing pin for the civilian market to prevent the occurrence of slam-fires and nasty lawsuits resulting from same. I guess no one ever said they were smart.

This issue could very easily explain why a friend of mine's brand-new .308 Scout rifle, right out of the box fires three-round bursts. He sent it back to the manufacturer twice for fix-its, but the matter is unresolved and unexplained.

Wehrmacht_45

Alot of rifles use floating pins.

jtmarine0831

It is not whether or not the rifle was made commercially or for the military but the nature of the action in these type of rifles that call for harder primers. The inertia of the bolt slaming closed on a live round causes the floating firing pin to jolt forward and actually contact the primer. If the action is in good order or the primer cup is "tough" enough then it will be fine. If not then the chances of a slam fire increase. Next time you get a chance or are around someone shooting a autoloading mil-spec rifle, AR's are a good example, Look at the primer on a round that has been chambered by firing the previous round but itself has not been fired. You will notice a light dimple in the primer, this was caused by the firing pin lightly striking the cup as the bolt slammed home. Another big reason that they recommend mil-spec ammo is the brute force at which the fired case is extracted from the chamber! This is one reason why shooters that reload for the M1A/M14 don't get the life out of brass as someone with a bolt gun would. Does this help with what I was trying to say before? If you want to know more let me know and I'll try not to confuse you.


quote:I would suggest owners of M1A's never drop a live round in the chamber and let the bolt go forward without a magazine in place. I did just that once and had a slam fire.

It was with my own reloads. I have shot hundreds upon hundreds of these rounds from the gun and never a problem, but when I dropped one in the chamber and let the bolt go without the mag in the gun, it went bang.

Having a mag in place slows down the bolt speed as either the follower or the next round in the mag rub on the bottom of the bolt. This will help prevent slam fires when the enertia of the bolt suddenly stops causing the firing pin to slap forward.

All American combat rifles have floating firing pins. The M1A, M-1 Garand, M-1 Carbine and M-16. I have shot lots of both .308 and 7.62X51 Nato from my M1A's with no cycling or accuracy problems.



Lefty is right onthe money here! Never just drop one in, feed it from the mag. If not you WILL have a slam fire, if not the first time, then maybe the second, but you will eventually!

Laredo Lefty

I would suggest owners of M1A's never drop a live round in the chamber and let the bolt go forward without a magazine in place. I did just that once and had a slam fire.

It was with my own reloads. I have shot hundreds upon hundreds of these rounds from the gun and never a problem, but when I dropped one in the chamber and let the bolt go without the mag in the gun, it went bang.

Having a mag in place slows down the bolt speed as either the follower or the next round in the mag rub on the bottom of the bolt. This will help prevent slam fires when the enertia of the bolt suddenly stops causing the firing pin to slap forward.

All American combat rifles have floating firing pins. The M1A, M-1 Garand, M-1 Carbine and M-16. I have shot lots of both .308 and 7.62X51 Nato from my M1A's with no cycling or accuracy problems.

cpermd

quote:Originally posted by jprice846
What is the ideal ammunition for an M1A1 Scout? I bought my son one of these and get get a good read on whether there's a correct size between 308 Win., or 7.62 51 or 7.62 54.

Anyone have a suggestion?

Thanks


I bet $100 it is not a M1A1.

CP

badsbsnf81

308 Win vs. 7.62x51 - They are not the same. SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi
Headspace is different. "Go Gauge" for the .308 is 1.630" vs. 1.635" for the 7.62x51. .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge.

Military brass is often has thicker casewalls and will probably have less powder capacity than commmercial .308 Win brass.


If you really want to read up on it, go to http://www.thegunzone.com/30cal.html

givette

Bads: givette here. Good post. Here's mine from an earlier discussion.

Ar-15 military chamber is "sloppier" than .223 civ (SAAMI). Different throat/leade. Designed to take higher pressure mil. 5.56 rounds. OK to shoot civ. 223 in AR's. Not OK to shoot Mil (5.56) in civ. rifles w/tighter chamber. (marked .223 rem).

M14's just the opposite. (We're talking box-stock M14 repros here, not altered from milspec). Civ .308 ammo is approx 1,200 psi higher than mil 7.62 NATO. With a different time-to-pressure peak. May be too forceful on gas operated parts. Not OK to shoot civ .308 Winchester in mil. 7.62 NATO rifles. OK to shoot mil. 7.62 NATO in civ rifles (marked .308 Winchester).


The above posting is a generality. I like to keep it simple. And if adhered to, you'll never walk the dangerous pressure minefield. Hope I helped. Joe

EDIT:Just remembered..a lower pressure civilian .308 loading was introduced to the shooting public at about the same time the M14 semiauto clone became popular. Should give you some bullet style choices. Joe