Brass Inspection -- Auto-Loading Rifles

[sinister]

A "Public Service Reminder" for those loading for semi-automatic rifles (particularly for .308s/7.62mm, but any gas-operated rifle).

Check your cases for incipient case head separation. You can do this by running a straightened paper clip or a simple tool (I use an Allen wrench) and feel inside the case, down by the case head, to determine if you have any case wall stretching and thinning. Most recommend (if shooting in an M1A or M14, or setting back the shoulders more than 2 thousandths) a quick inspection to prevent having to use a broken case extractor.

This particular photo is of a Lake City 85 7.62mm M852 Match case, found on inspection after annealing. The impending separation crack contrasts well against the crenellations designating a military "Match" case).

I have no idea how many loads I have on this particular piece of brass. It was first-fired in an M14, then loaded and shot through a variety of gas-operated rifles (M1A, AR-10T, and AR-10T Carbine). I checked the rest of the cases in this particular 100-piece lot and threw away half of them, just to be preventative.

1985 may or may not indicate how long you can use cases shot in autoloaders. Many M14 shooters will toss after the fourth firing.

I have loaded 7.62 on both a Dillon and a Redding T-7 using RCBS Small Base dies.

 

[NoFail]

Re: Brass Inspection -- Auto-Loading Rifles

Depending on the load, I'm lucky to get 4 firings out of any brass for my LR-308.

Loose primer pockets kill it. Extractor swipes & bending back rims is worth mentioning.

I have become a 1x fired brass collector.

 

[ksthomas]

Re: Brass Inspection -- Auto-Loading Rifles

Sinister,

I don't recommend reloading the M852 cases for exactly the reason shown in your photo. The cannelure was added to these rounds to indicate "Not For Combat Use", but were placed exactly where there's already a potential weak point in any rifle case. Another fine example proving that the Ordnance Corps really doesn't look at a cases reloadability as one of their design criteria. This cannelure was dropped when the M118LR replaced both the M118 Special Ball and M852 Match ammo, and I'd recommend these cases as being better candidates for reloading.

 

[sinister]

Re: Brass Inspection -- Auto-Loading Rifles

I'm not sure they weaken the case, <span style="font-style: italic">per se</span>, as the case stretching is more apparent inside the case (since they're re-sized from outside-in in a die. Much like how crenellation on a Sierra 77 in Mark 262 variants aren't really a cannelure groove for case mouth crimping). They seem to make the cases easier to visually inspect.

I'm not sure whether or not M118LR or Federal brass lasts any longer in self-loaders, especially if the shoulders are set back more than 2 thousandths every time.

Talking with guys who shoot Lapua brass out of Long Range - Service M14s they get about the same results.

I've got a bunch of National Match brass that will eventually pass to my son.

 

[ksthomas]

Re: Brass Inspection -- Auto-Loading Rifles

Funny story on the 77SMKs, and yeah, you're right, it's a cannelure in name only. Strictly a cosmetic addition that allows them to call then "cannelured" which is what's specified in the military contracts for this bullet. They won't take delivery of bullets that aren't cannelured, yet Sierra (as well as most of the ordnance guys who are involved in the project) know tha cannelures almost always kill accuracy. The solution was a fig leaf; roll just enough of a "cannelure" on the bullet that it can technically pass muster, and meet contract specs for the government bean counters.

As far as the M852 knurling, yeah, they weaken the case. In guns that are unusually hard on brass (such as the M14 family), that's just not a positive attribute. Wouldn't bee nearly as bashful about using them in a bolt gun, though.

 

[m1match]

Re: Brass Inspection -- Auto-Loading Rifles

Although I do not have depth of experience that Kevin has, I would say that the M852 cases can be reloaded with excellent results. I have heard that the cannelure in the LC Match cases for the M852 ammo are a potential weak spot, but I never had a problem with them shooting them in 308 M1 Garands and bolt guns.

I have been using LC 94 Match cases since 1998 when the CMP sold new unprimed LC 94 Match cases in lots of 2000 in a 20mm ammo can. I used it to load match loads for my match tuned M1 Garands, which I was shooting in NRA Highpower competition. Before I switched to the AR in 2004 I shot close to 5,000 rounds of 308 in those 6 years and I only went through 500 cases. Yes that's right, I was getting 10 loadings from that LC 94 Match case and a load of 42.2 grains of IMR 4064, CCI #34 Military primers, and a Sierra 168 MK. THE KEY TO THIS was I used a precision mic to measure precisely measure how much I was setting the shoulder of the case back during resizing. I set my dies and rechecked them regularly to set the shoulder back no more than 3 thousandths. I never had a single headspace separation and my cases after 10 firings were still good except I was getting case necks cracking.

One thing I can't answer is I have been told that the gas piston system of the M14 has more violent extraction than the M1 Garand. I also know that M14 shooters say to chuck brass after 4 loadings. But in a 308 M1 Garand, you can get very long case life with careful reloading.

I no longer shoot the Garand in competition, but I'm still using LC 94 Match cases from that batch of 2000 I bought in 1998 to load my 308 bolt gun loads with excellent results.

One other thing, I never found the need to use Small Base dies. Std. RCBS and Redding dies worked fine in my match tuned Garands which had match chambers in either an Obermeyer or Douglas barrel. For that matter, I've never found a need for Small Base dies in any of my semi auto rifles.

 

[sinister]

Re: Brass Inspection -- Auto-Loading Rifles

Kevin and M1Match, thank you.

I no longer own an M1A but shoot 7.62 through an AR-10T, a 10T carbine, and a 700. Both autoloaders have Tubb Carrier Weight Systems as well as the heaviest Clint Butler Slash buffers. I don't think ARs (like your mentioned 7.62 M1) beat up brass as badly as the M14 (the piston tending to shove the op rod and blast cases out of the chamber quicker -- watch M21s firing at night and you get a great sparks and fireworks show).

I started using a small base die for autoloaders when I had a slam-fire with a National Match AR at Quantico Range 4 during an off-hand training session. Everything I had read up to that point had assured me a Dillon die was small-based. Not true. I'm not sure who was more surprised -- me, or our coach on the spotting scope between me and the A-shooter.