Headspace for M1A and FAL?

[eldon519]

I've got an M1A that I reload for, and I usually try to control headspace of my rounds at 1.634". The fired brass coming out of the rifle usually has headspace on the order of 1.634-1.636". I have seen one or two cases come out as high as 1.637".

I've recently started reloading for my FAL, and I am planning on trying to set the headspace for these rounds as well. On most of the rounds I've measured, the fired cases read around 1.631" on average, but I have found a case or two measuring around 1.635". I put one of these 1.635" fired cases in my FAL's chamber and let the bolt fly, and it appeared the action closed completely on the round. I tried it a time or two, and in each case it appeared to close all the way.

Is there any reason for me to try to reload to a headspace closer 1.631" for my FAL, or could I just load for it with the same die settings as I use for my M1A? Is there any explanation for why most of the fired cases from my FAL would come out at 1.631" but from time to time, one measures 1.635"? Since I have had cases come out of my M1A with headspace as high as 1.637", should I consider adjusting the headspace of my reloads closer to 1.636-1.637" to maximize brass life? I have two .308 dies, so it would be possible for me to achieve different settings for the brass. I already keep brass used in my FAL and brass used in my M1A separate.

If you can't tell, I'm relatively new at reloading for bottle neck cases and autoloading rifles.

 

[rcmodel]

should I consider adjusting the headspace of my reloads closer to 1.636-1.637" to maximize brass life?

If it was me, I would forget what the fired cases measure.

Adjust the sizing die so the rifles bolts will just still close reliably on the sized cases.
And then keep the loaded & fired rounds seperate for the two rifles.

That will give minimum case stretch and maximum case life.

rcmodel

 

[Slamfire]

If it was me, I would forget what the fired cases measure.

Adjust the sizing die so the rifles bolts will just still close reliably on the sized cases.
And then keep the loaded & fired rounds seperate for the two rifles.

That will give minimum case stretch and maximum case life.

Good advice. Unfortunately, that FN/FAL is going to give you short case life regardless of what you do. And depending on the gas port size of the M1a, whether it has a long dwell or a short dwell period, your case life can be five reloads, (short dwell) or more.

The FN/FAL is a rear locker. I don't remember what the number is for compression of steel, but lets say it is .001" per inch. I am going to say that the FN bolt locking lug is three inches back from the bolt face. So the case will be stretched at least .003" just on firing. Then the poor case is going to be stretched during extraction.

I have been told that five reloads is doing good for a FAL. I don't know, I am shooting Berdan through mine, and I don't reload those cases. I can tell you, I fired 1000 rounds of Cavim through my FAL, and the fired cases were huge.

Those chambers must have a secondary function as Blimp hangers.

 

[USSR]

eldon519,

Makes no sense to me to have loaded ammo that is not usable in a rifle chambered for that cartridge. I have a FAL, and a FN SPR. I set my cartridge headspace so as to just fit my shortest chamber (the SPR), and it works well in the FAL (2MOA at 100 yards with milsurp component handloads).

Don

 

[30Cal]

I suspect your longer cases are the ones that stuck a little more to the chamber wall and got yanked longer by the extractor.

I'd put them all at the 1.629" and call it good.

 

[rcmodel]

Another thing is that it is an exercise in frustration trying to set minimum headspace cartridge length on an self-stuffer.

There is a phenomenon known as "Drive-In" that occurs when a autoloader slams a round into the chamber.

That can actually set the case shoulder back slightly just as if you had sized it too short to begin with.

If you were to measure some rounds after they had been fed through the rifle by firing, they may be slightly shorter then when you so carefully loaded them.

rcmodel

 

[Bullet]

I've got an M1A that I reload for, and I usually try to control headspace of my rounds at 1.634". The fired brass coming out of the rifle usually has headspace on the order of 1.634-1.636". I have seen one or two cases come out as high as 1.637".

Cartridges do not have headspace. Headspace is a firearm manufacturing tolerance only.

 

[USSR]

eldon519,

I'm assuming your fired case measurements were made using cartridges that were fired and ejected from your rifle. You may want to open your gas adjustment up all the way on your FAL so that your case remains in the chamber, and your action doesn't open up and start extracting when there is still pressure, and THEN measure the case headspace.

Don

 

[rcmodel]

Cartridges do not have headspace.

Lets not start that thread again!

Everyone knows what he is asking about when he refers to sizing his cases to minimum headspace.

Lets just leave it at that before we get into the "clips & magazines" & "bullets & cartridges" arguments again.

rcmodel

 

[steve4102]

Is there any explanation for why most of the fired cases from my FAL would come out at 1.631" but from time to time, one measures 1.635"?

When a round is fired in an auto-loader the brass expands to fit the chamber the same as in a bolt action. The difference is that the brass may still be under a slight bit of pressure when it is extracted. This tiny bit of pressure can cause the fired brass to be longer and also fatter than the actual chamber dimensions. This oversizing of the brass is not always consistant due to many factors such as barrel heat, powder charge and powder burn rate. Here is an article worth reading on loading for service rifles.
http://www.zediker.com/downloads/14_loading.pdf

 

[USSR]

When a round is fired in an auto-loader the brass expands to fit the chamber the same as in a bolt action. The difference is that the brass may still be under a slight bit of pressure when it is extracted. This tiny bit of pressure can cause the fired brass to be longer and also fatter than the actual chamber dimensions. This oversizing of the brass is not always consistant due to many factors such as barrel heat, powder charge and powder burn rate.

Yep, exactly what I was talking about.

Don

 

[eldon519]

Thanks for the advice, I'm currently tinkering with my dies to bring the loaded rounds down to about 1.630".

I read the posted exert from Glen Zediker's book. Is 5 firings (4 reloadings on once-fired brass) really all you can hope to get from M14/M1A brass? He seemed to suggest that Lake City or IMI brass was really the only suitable choice for these rifles. I'm currently using Winchester brass which appears to be doing fine. Am I headed for trouble by not using military brass? What is the fear of using the brass more than 5 times, case head separation?

Also, I'm currently loading with BL-C(2) because I read that this is what they used to use in military 7.62x51 ammunition, but the article seemed to suggest it might be a little bit on the fast side. Should I change to something like H4895? I really like using spherical powder because it meters so well, and I've been told it burns cooler and can extend barrel life.

 

[steve4102]

Should I change to something like H4895? I really like using spherical powder because it meters so well,

You can go with a slower powder and still take advantage of the easy metering of ball type powders. Here are a few example.

2460 Accurate's Ted Curtis' favorite powder, this medium-burning Spherical propellant is increasing in popularity with NRA, IHMSA, and bench rest shooters. Useful in a wide variety of cartridges, it is slightly slower than 2230 and shows a small pressure advantage over 2230 in bores of 7mm and over. An excellent choice in .308 Winchester, 2460 is appropriate for use with M1 and M14 (M1A) service rifles.
http://accuratepowder.com/data/2460.htm

2520 One of the most popular powders of all time, this medium-slow burning, Spherical propellant gives excellent results in medium capacity cases (308 class) and certain applications in large bore cartridges. This powder was in the winner's circle in NRA High Power competition before it had been on the market two years! 2520 is the first choice for target shooters using 168 grain bullets in the .308 Winchester. 2520 has a pressure curve appropriate for use with M1 and M14 (M1A) service rifles. In fact, some shooters now call it the "Camp Perry" powder.

http://accuratepowder.com/data/2520.htm

TAC
Ramshot TAC is a versatile rifle powder that performs well in a number of different calibers. TAC has the ability to provide some of the industry's highest velocities for 80 grain bullets in the .223 caliber while maintaining SAAMI pressure guidelines. TAC is a double-based powder providing for ease of metering and consistent charge weights.

Ideal Calibers:
.223 Rem, 308 Win

Bulk Density (grams/liter) 985

Packaged in 1lb. and 8lb. containers.
http://www.ramshot.com/powders/

 

[Sunray]

No matter what you do to a case does absolutely nothing to headspace. You can't set headspace on a cartridge. There is no headspace on a cartridge. Despite rumours to the contrary. Just FL resize every time and you'll be fine.
There's no pressure left either.

 

[USSR]

Sunray,

Give it up. Manufacturers sell tools to measure case headspace, 99% of advanced reloaders know what it is, even Boots Obermeyer, the dean of American barrelmakers refers to it. Why you continue to desire to remain in the dark is beyond me.

Don

 

[Sunray]

"...case headspace..." Because there's no such thing, despite what your Dean says.

 

[steve4102]

No matter what you do to a case does absolutely nothing to headspace. You can't set headspace on a cartridge.

You are either looking for a fight based on semantics or you are on "Crack".

OK, I'll play your silly game. Headspace has nothing to do with cartridge, happy? Now follow along here, I measure some new unfired brass from case head to shoulder and record that measurement. I fire this brass in my rifle. I then measure from head to shoulder again. I find that my brass has grown .00xxx. I then set up my FL dies accordingly. I can either bump the should back a thou or two for hunting or I can bump it up a thou or two for a crush fit. Either way I have adjusted my dies so as to fit my chambers "Headspace". Yes, I did not change Chamber Headspace with my brass or dies, but I did adjust my sized brass to elimiante excess "SLOP". Does that make you feel better? Using the word "SLOP" instead of "headspace".

 

[GunTech]

I've been using military brass in my M1A with the generous 7.62x51 chamber. Get used to shorter brass life. Even using an annealer, brass doesn't seem to last all that long I've found LC is good, Winchester not too bad and Remington and Federal brass not so good in the M1A and particularly the FAL. If I don't set the gas adjustment on my FAL to the minimum possible, it will rip the head off RP brass about 30% of the time on first firing.

 

[Bullet]

steve4102

OK, I'll play your silly game. Headspace has nothing to do with cartridge, happy? Now follow along here, I measure some new unfired brass from case head to shoulder and record that measurement. I fire this brass in my rifle. I then measure from head to shoulder again. I find that my brass has grown .00xxx. I then set up my FL dies accordingly. I can either bump the should back a thou or two for hunting or I can bump it up a thou or two for a crush fit. Either way I have adjusted my dies so as to fit my chambers "Headspace". Yes, I did not change Chamber Headspace with my brass or dies, but I did adjust my sized brass to elimiante excess "SLOP". Does that make you feel better? Using the word "SLOP" instead of "headspace".

How about using the correct term Head Clearance instead of SLOP or Headspace?

From SAAMI -

HEAD CLEARANCE
The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.

 

[eldon519]

No matter what you do to a case does absolutely nothing to headspace. You can't set headspace on a cartridge. There is no headspace on a cartridge. Despite rumours to the contrary. Just FL resize every time and you'll be fine.
There's no pressure left either.

Thanks for the heads up. I'll try to be more accurate with my terminology.

Would it improve brass life for me to fire both the M1A and FAL with the gas system deactivated (put them in the rifled grenade position)? I'm just shooting off a bench to try to develop my marksmanship skills before moving to field positions. I'm also not shooting very high-pressure loads. I'm currently loading 46.0 gr. of BL-C(2) under a 150-grain bullet. Hodgdon lists 45.0 gr as starting and 48.0 gr as maximum. I'm just going for military specification of around 2700 fps.

 

[Bullet]

Sunray
There's no pressure left either.

This seems contrary to what I’ve been told. Could you explain?

.

 

[USSR]

How about using the correct term Head Clearance instead of SLOP or Headspace?

Bullet,

We've been over this with you hundreds of times. Head clearance is the distance between the boltface and the base of the case. It's measurement is just a few thousands (.003", .004", etc.). The case measurements we are taking are (in .308 Win) of about 1.630", which is just shy of say a 1.632" chamber measurement. Can you not see how big a difference this is, and that we are not talking about the minute distance between boltface and headstamp on case?

Don

 

[Bullet]

USSR
Head clearance is the distance between the boltface and the base of the case. It's measurement is just a few thousands (.003", .004", etc.). The case measurements we are taking are (in .308 Win) of about 1.630", which is just shy of say a 1.632" chamber measurement.

1.632" - 1.630” = .002 difference = .002 Head Clearance

 

[Doug b]

nice hyjack bullet

 

[Bullet]

Sorry eldon519 I don’t want to hyjack your thread. So back to your question -

Would it improve brass life for me to fire both the M1A and FAL with the gas system deactivated (put them in the rifled grenade position)? I'm just shooting off a bench to try to develop my marksmanship skills before moving to field positions. I'm also not shooting very high-pressure loads. I'm currently loading 46.0 gr. of BL-C(2) under a 150-grain bullet. Hodgdon lists 45.0 gr as starting and 48.0 gr as maximum. I'm just going for military specification of around 2700 fps.