7.62 NATO vs 308 Win. What to make of this?

[DocRock]

So, I bought a ton of once fired Lake City 7.62 Nato, almost certainly machine gun fired brass. I use and RCBS narrow base die to full length resize and swage the crimps with a CH4D die. Trim and go.

I recently rescued and restored a 1967 vintage Savage M99 E carbine. So I loaded some 150 grs Sierra GK into this brass and went to the range to sight in. Little stiff chambering, maybe this chamber needs the shoulder bumped a bit more. Fired. Will not extract. Eventually, with enough force on the lever, the extractor popped off the rim. Knocked the case out with a brush and rod. Tried another round. Same thing. Fired case? Very tight fit going back in.

I had a box of 150 grs Federal Fusion .308 Win. Three shots, three easy extractions.

So. Is it that the LC brass is too expanded even after running through the narrow base FL die? I've ordered a Field Gauge to check headspace but it seems like the brass to me.

Thoughts?

 

[Walkalong]

but it seems like the brass to me.

Me too.

 

[gotboostvr]

To my understanding, the generous chambers on most machine guns can cause case head separation when reloading due to excessive stretching of the case.

That brass may be toast no matter what dies you use.

 

[243winxb]

Powder used & how many grains?

Given the reduced capacity of military brass, you should reduce posted max loads by 1.5 grains when loading with Lake City

https://www.accurateshooter.com/cartridge-guides/308win/

 

[jmr40]

What was the load? Military brass has less volume, so similar powder charges will produce greater pressure. If you used the same powder charge and bullet you used when using most commercial brass you might have an overloaded cartridge in that brass. I've only loaded military brass once, but I dropped down 2-3 gr under what I normally used and had no issues. I ended up getting the same speeds as my loads in commercial brass even with less powder.

If the unfired cartridges feed and eject I wouldn't think the brass is oversized. But it does sound like the shoulder may need to be bumped back a little

 

[lightman]

I believe its a combo of the machine gun brass and your rifle. Nothing against your rifle but lever actions are not the strongest type of system for chambering and extracting rounds. And you are really challenging it with that brass.

If I remember correctly,RCBS used to suggest their small base dies for the Browning BAR (not the WW2 BAR), the Browning BLR and the Savage 99. This suggest that either the leverage is weak or the chambers are tighter than normal or maybe both.

Please don't take this as an insult to your rifle or your brass. 99's are great rifles and LC is great brass. Its just that machine gun brass and 99's just don't play well together.

 

[Random 8]

I have worked with an M99 in .308 with military brass. Brass was WCC reman/pulldown. The brass fired in my wife's bolt action, then FL sized and fired in the M99 worked perfectly. The brass fired in my CETME DRLB battle rifle, then FL resized and fired in the M99 choked it, but would function "OK" in my wife's bolt action. The M99 does not like brass that has been chewed on by nasty automatic weapons. I'd imagine you'd have issues with brass fired in a 7.62 M1 Garand or FAL as well. I'd stick to commercial .308 brass fired in more pedestrian actions in your Savage.

I'd be cautious about bumping the shoulder on cartridges to be fired in an M99. They're rather stretchy to begin with, and the .308 win round is pushing that action near the edge. You really don't want any cartridge related headspace coming into that equation unless you're backing the loads significantly off max. Even then, .308 commercial brass is common enough that it may not be worth doing.

 

[DocRock]

Thanks folks. They were 150s over 43 grs IMR4064 so nowhere near max pressure for military brass. Given the absolute ease of the Federal 308 brass extracting and your experiences related above, I suppose it's pretty simple: no LC in the M99.

Appreciate the advuce, thanks.

 

[FROGO207]

You could measure the base of the brass and the rim. Both on an unfired commercial and that LC. Bet you find the base is blown out some. At least you didn't buy 10K of that brass ahead. I bet someone will buy that "prepped" brass.

 

[DocRock]

You could measure the base of the brass and the rim. Both on an unfired commercial and that LC. Bet you find the base is blown out some. At least you didn't buy 10K of that brass ahead. I bet someone will buy that "prepped" brass.

No worries. I have a PTR91 that lives on a steady diet of nasty machine gun LC and PPU M80. It will continue to do so. The Savage will enjoy a more refined diet henceforth.

 

[Pivot Dr]

I’ve found that a trip through my carbide 45 acp sizing die corrects that oversized fired military brass problem. I make all kinds of wildcat and form different chamberings out of 308 and once fired military brass. Some chambers it fits, others I have to squeeze it down. Unfired pulled military brass doesn’t give me that problem. If you don’t have 45 acp dies but do have a lot of brass, a carbide die is a pretty cheap fix. You only have to do it the first time, not every load.

BP

 

[FROGO207]

That 99 will eat 180 grain bullets for max accuracy if it is like mine.

 

[z7]

I’ve used the LC brass,

it is hard and tough and will spring back to shape, anneal the shoulder/necks and bump it back, but don’t be surprised if it refuses to work

I can shoot it in my custom gun, but the same batch of reloads won’t chamber in my dads mossberg bolt 308

 

[Nevmavrick]

The military brass necks are a bit thicker. It would be best to turn the necks some.
The necks aren't releasing the bullets quite readily.
That combined with the tighter chamber and reduced leverage of the excellent M99!
have fun,
Gene

 

[Riomouse911]

I learned to never shoot military brass reloads, or loaded surplus ammo, in a Savage 99. Every time I did with my 99F the military cases would stick after firing and need to be briskly pushed out with a cleaning rod. Every time.

No .308 Win factory ammo ever stuck in the gun like the 7.62 military ammo did.

I have no idea why this occurred, but it did. Use standard commercial .308 cases for your Savage 99 loads and you’ll be fine.

Stay safe.

 

[cfullgraf]

I cannot help with the Savage 99 but it seems from what limited knowledge I have on the Savage 99, the comments seem to be on point.

Cases fired in a machine gun is a different matter. I bought some for use in my Springfield M1A. I used a small base die to resize them and they chambered just fine.

But, I had an excessive number of case head separations with the cases that I discarded the lot, many not even fired by me. I'll only use new cases in my M1A, not trusting the history of once fired stuff.

 

[jmorris]

I start out by trying sized cases in the firearm, before I load them up, how do the sized cases alone function?

That eliminates the possibility of the load being the problem as well as confirms the sizing process is/not the problem. So, no matter what you have narrowed your focus by 50%.

There are about 40 .308 cases in a pound, so if you have 80,000 of them (a ton), it should be worth figuring out how to utilize them.

 

[Charlie98]

I've got experience with once-fired LC in my 99F... none of it necessarily bad, per se. Now, that same brass in my M1a... serious problems. Chuck mentioned case head separations... which is typical of the M1a action, but I had case head failures... complete blow outs of the case head. Long story short, I got a bad batch of brass, but it was enough of a problem that I have sworn off anyone else's 'once-fired' rifle anything... I source my own new brass, or source it from my once-fired factory ammo, and process it myself. I never had a case blow out on me in the 99, I'll chalk that up to 'lucky me.' In the M1a, it blew the magazine out and ran some breeze through my hair.

I've also found the 99 to be very sensitive to cartridge OAL... even cartridges right at max OAL tended to hang up in the magazine. These days my 99 only sees cast bullets, but when I was working with it after I got it, I had some feeding problems, and magazine jams with longer jacketed bullets.