Lake city brass sizing and primer crimps

[Morgan321]

Stupid question time. I'm new to reloading. I have a large quantity of lake city m72 brass that has all been fired in my gun. About 3% of the m72 brass is hard to chamber. Hard meaning slight resistance when closing the bolt. The cases are not too long. The rounds fired from these cases are not accurate, they fall as much as 3 moa from other rounds. After removing the cases they have slight rub marks where the extractor and ejector touch the case, ie the case does not rotate with the bolt as it is closed.

I switched to a full length die and tried sizing these cases. The die leaves a very narrow shiny ring around the large(bottom) end of the tapered part of the case right where the taper starts. After sizing the empty cases all chamber butter smooth. I verified the empty cases still chamber with resistance before sizing to ensure it was the cases causing the resistance.

Any reason why some of these cases seem to be not quite sized properly? I'm going to keep them separate and verify that they now are accurate before adding them to the pile.


The M2 brass has crimped primers. Do loose primer pockets ever limit the life of m2 brass? If so, what is the best way to remove the crimp to get the most life from the brass?

 

[427Cobra]

Any brass fired in another weapon needs to be FL resized with a small base die, after that a plano FL die(get a redding Type S) will be fine, set your FL die up with a head space gauge, measure fired(IN YOUR CHAMBER) decapped brass, use the longest case cases as your reference, bump the shoulder .0015 for bolt guns and .003 for semi autos, SUCKERS neck size only.

 

[bigedp51]

These cases would have been fired in a M1 Garand with a larger diameter chamber and longer headspace than commercial SAAMI chambers. "ANYTIME" you buy once fired military brass you should resize it with a small base die.

The problem you are having is brass spring back after sizing, the small base dies return the brass to minimum case diementions.

As you can see below 427Cobra is almost as smart and good looking as I am, ;-) the black box below are small base dies. My once fired military cases are sized with the small base dies, rotated 180 and sized again counting to three at the top of the ram stroke. Pausing at the top of the ram stroke reduces brass spring back and tells the brass to stay put and "FIT" smaller chambers. Please note brass fired in machine guns is even worse because the chambers are even larger in diameter and longer in headspace making the spring back worse.

If you plan on using a lot of military brass I would invest in the dillon primer pocket swager. This method does not remove any brass and the crimp is pushed outward and tightens the primer pocket. Removing brass by reaming the crimp can cause over sized primer pockets. I say this because the act of crimping the primer pocket can make the primer pocket diameter increase under pressure. Bottom line, swaging primer pockets is a better method and you will have less loose primer pockets when finished.

Below a pin gauge used as a NO-GO gauge for oversized primer pockets.

 

[Mad_Charlie]

Would you mind sharing the sizes of pins that you use for gauging pockets?

 

[bigedp51]

Would you mind sharing the sizes of pins that you use for gauging pockets?

First I bought the small rifle primer gauge below but the NO-GO end was .175 and if that end entered the primer pocket you could seat primers with your fingers. I then ordered a .1745 pin gauge to use as a NO-GO gauge, this is .0005 smaller than the average small rifle primer.

You can order the pin gauges below.

Vermont Gage Steel No-Go Plug Gage, Tolerance Class ZZ (Inch): Amazon.com: Industrial & Scientific

Primer pocket specs below.

If I can push the primer out with one finger using a Lee depriming tool the case goes in the scrap bucket.

Just remember primers come in different diameters, if my Remington 7 1/2 are loose my CCI BR4 might fix the problem.

 

[Morgan321]

The brass has all been fired only in my gun. It's like a few cases weren't sized quite correctly at the factory. My dies are not small base either.

So a swager will let the primer pocket last longer? That seems reasonable, any comments on how many times this stuff can be reloaded?

 

[Pinecone]

Personally I have not found a need for a small base sizer. And I know I have machine gun brass in .308.

As for how many reloadings, it depends on the rifle and if you anneal the cases.

I know the recommendations for M1A/M14 is 4 reloadings, then toss the brass.

 

[M40_A1]

I know the recommendations for M1A/M14 is 4 reloadings, then toss the brass.

If there is no evidence of separation or cracking, what would be the reason for this?

 

[M14 Shooter]

The M1-A/M14 is very tough on the Brass during the extraction process.(Brass stretches a lot ).If shot out of a tight chambered NM M1-A you may get one or two more firings .But the general consensus with with most Service rifle shooters is to toss after 3-4 firings.Its not worth the risk having a case fail and do damage to rifle or the shooter.A lot of times you will see the ring form near the case head after 3-4 firing on a standard chamber/mil spec chamber.

Regards,Mike

 

[M40_A1]

The M1-A/M14 is very tough on the Brass during the extraction process.(Brass stretches a lot ).If shot out of a tight chambered NM M1-A you may get one or two more firings .But the general consensus with with most Service rifle shooters is to toss after 3-4 firings.Its not worth the risk having a case fail and do damage to rifle or the shooter.A lot of times you will see the ring form near the case head after 3-4 firing on a standard chamber/mil spec chamber.

Regards,Mike

Thankyou. I'll have to find out if the same is true for 30-06 Garands then.

 

[Morgan321]

I have unfired up to 4 times fired m2 and m72 brass with a ring near the head of the case. All fired in a factory rem 700. Even unfired has a ring. Can't feel anything inside the case with a bent piece of wire...

 

[SWThomas]

I would bump the shoulder back at least 0.005, maybe a little more, when resizing brass that has been fired in your rifle. I have found that the headspace grows about 0.002 once I seat a bullet. Give yourself a little room for this. Every round that I sized to bump back 0.003-0.005 still chambered and fired fine, but if I tried to extract one by pulling the charging handle back, I had to bump the stock on something to get that round to unseat from the chamber. Not very good for reliabilty IMO. Now I bump my shoulders back 0.010 from the fired case headspace, which gives me roughly 0.008 once the bullets are seated.

 

[Mad_Charlie]

Thank you bigedp51, I can make the pins with no problem, just needed some dimensions.

I use that same trick with the depriming tool when I have a doubt about how a primer seats, if they just push right back out, it's to the scrap bucket.

 

[Mad_Charlie]

I would bump the shoulder back at least 0.005, maybe a little more, when resizing brass that has been fired in your rifle. I have found that the headspace grows about 0.002 once I seat a bullet. Give yourself a little room for this. Every round that I sized to bump back 0.003-0.005 still chambered and fired fine, but if I tried to extract one by pulling the charging handle back, I had to bump the stock on something to get that round to unseat from the chamber. Not very good for reliabilty IMO. Now I bump my shoulders back 0.010 from the fired case headspace, which gives me roughly 0.008 once the bullets are seated.

That's interesting, never had that happen before...

.010 sure seems to be an awful lot of shoulder bump to me, of course I am not loading for your rifle...

 

[ZombieMonkey]

Sounds like you just need to set the shoulder back a little more. Verify how much it was set back before and after resizing with a gauge. I set my semi-auto brass back 0.003" and have never had issues for any rifles I load for or for friends when I've bumped the cases back this much. The fact that it has all been fired through your gun and still is having issues in your gun after full length sizing tells me you need to adjust your die.

And as others have said, swage your primer pockets instead of reaming them. I was reaming them before and found that it kills your hands and I am not too fond of removing brass when not necessary.

 

[ZombieMonkey]

That's interesting, never had that happen before...

.010 sure seems to be an awful lot of shoulder bump to me, of course I am not loading for your rifle...

That's because it is a lot of shoulder bump.

0.001-0.002 is typically used on a bolt gun, while 0.003-0.004 is typically what is used for a semi-auto. Anything more and you are overworking your brass. If someone truly needs more bump than that to get their cases to feed well then I'd start looking at the die as possibly out of spec before anything else, it happens.

 

[Morgan321]

The brass is fine after sizing. My question was why does the unfired brass have this problem?

 

[Mad_Charlie]

Unfired cases are just raw material, they should be processed as once fired to make them fit your rifle.

I have to process new cases to make them fit my 700, as a matter of convenience, I keep a die set up for my 700 (1.627) and a die set up for my M1a (1.632) I also have the Redding Shellholder set to help make "adjustments" easier if needed (different headstamps etc.) I use a Precision Mic to measure my cartridge headspace, and have been known to grind a few thou off of a shellholder with my surface grinder to bring cases to dimension.

The 700 needs the shoulder bumped a few thou shorter than new cases usually are, or the bolt is a little harder to close (on empty case)

Maybe I missed it, but how are you measuring your cartridge headspace??

The "ring" you're getting, as you describe it, sounds like a normal die mark to me. Swageing primer pockets is the way to fly for crimped primers, the pockets MAY also need to be uniformed, I uniform all of my military crimped cases.

 

[JGorski]

Any brass fired in another weapon needs to be FL resized with a small base die, after that a plano FL die(get a redding Type S) will be fine, set your FL die up with a head space gauge, measure fired(IN YOUR CHAMBER) decapped brass, use the longest case cases as your reference, bump the shoulder .0015 for bolt guns and .003 for semi autos, SUCKERS neck size only.

Coughing while I say, BULLSHIT! Remember me guys? I bought 100pcs of machine gun fired mixed military 7.62 brass from Bobcat brass, sized them with a Hornady FL Custom bushing die, while bumping the shoulder back .002 -003", just seated the bullets an hour ago, and they fit perfectly in my Remington chamber, sure, I did have to trim them quite a bit but they fit just like a factory round does, so I'm another one that doesnt need a small base die, if your regular dies don't size that military brass enough, I'd ditch it, or, maybe your chamber is too big for it's own good, I mean too small for it's own good.

 

[Pinecone]

If there is no evidence of separation or cracking, what would be the reason for this?

The M1A/M14 starts the extraction before the case returns to a rest size, meaning the case gets stretched just above the head.

It is not neck problems, but case head separations that can be a problem.

A VERY good reference: http://www.zediker.com/downloads/14_loading.pdf

 

[ZombieMonkey]

Coughing while I say, BULLSHIT! .

Thank you for bringing that up, forgot to mention that! If your regular die setup will not resize the case with the appropriate amount of shoulder bump then you may be a candidate for a small base die as your chamber is likely on the small side. Most people do not have a legitimate need for a small base die, end of story.