CCI #400 Primers in AR's

[Jocko]

Had a fella give me 1000 CCI #400 small rifle primers. Anyone have first hand
experience using these in their AR? Been reading some info on the net - it's 50-50 on them, some folks say thats all they've used for years and no problems and others said they have had slam fires because they are soft.
I've always thought CCI's are the hardest of primers. I know CCI make the mil-spec primers, I'm asking about the #400's.

If anyone loads with these place let me know your thoughts.

Thanks a bunch

Information

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[hagar in SC]

CCI's are fine, it is the Winchesters that slamfire. Been shooting Cci's for the last 2 years and no issues whatsoever. I do prefer Remington 7.5 but they are hard to find.

[browningautorifle]

I bought 6000 CCI 400's for use in AR's only. Never had any slam fires with them. And as a matter of fact, I never had a slam fire in an AR either in the military or my own rifles. I don't even know of anyone who had one. Some of these guys must be doing something wrong.

[jmoore]

Main problem w/ standard small rifle primers is that the cup thickness is thinner than the magnum or "mil-spec" primers. Generally rated at about 45000 psi. Slamfires might be more likely, but mostly what happens is that the primers will get pinhole leaks at the firing pin indent and eventually erode the pin and possibly the firing pin hole. Its not easily noticed at first but it gets progressively worse as the pin tip gets first roughened and then eroded.

Depends on the loads your shooting, of course. Check the fired primers w/ a magnifying lens for a tiny dark spot in the deepest part of the indentation. Learned this the hard way, BTW. No dramas except a ruined F/P after about 100 rds. I believe MOLON on AR15.com wrote a fairly definitive bit on all the particulars some time back, but that site doesn't get along w/ this computer, so I'm not gonna check to see if its still there. Ammo section, I think it was in.
I do remember that about the only difference between std and mag SR primers was the cup thickness (depending on brand). Maybe 0.010" dif.!

"Benchrest" primers are just very nice SR magnums, as those rounds tend to run best at higher pressures.

[jmoore]

This article adresses your situation exactly, I believe!

Primers And Pressure

Its short and to the point, AND deals w/ the exact primer you mentioned. My experience was the same, once I noticed it!

[browningautorifle]

That's an interesting article. I thought Federal 100's were the thinnest pistol primer but they say they're all .17 thick.

[joem]

CCI primers was all I used since 1995. Never had any problems. Now I can't find them.

[Powder Hound]

I just began reloading for the 1st time last month and so far have run several hundred rounds of CCI primed reloads thru the M-4. I've had complete success with the primers and would expect that if anyone were to have problems with them, it would be someone like myself that barely has any knowledgable idea of what I am doing.

[jmoore]

Its such a small perforation in the primer that when it does happen its hard to see- at first. The problem arises if increasing frequency and severity as the firing pin tip is roughened either through normal wear(worse if you shoot in dirty environs such as the sandy deck at Ft. Benning) or hot gas erosion. Considering the price of firing pins its not a HUGE deal unless there's enough gas leakage to flame cut the firing pin hole in your bolt.

Its more of an annoyance than a safety thing.