CCI 5.56 Military primer

[Gottahaveone]

I am unfortunate to have been bitten by the AR bug a few months ago. At current ammo prices I decided it was time to start rolling my own. I have loaded tens of thousands of (mostly pistol) rounds so I know one end of a press from the other. However, I have never loaded for a semi-auto rifle. I was looking on the web for bullets when I found CCI 5.56 Military primers. They are supposed to be "military spec" for sensitivity to help avoid a slamfire. I already have several thousand CCI 400 small rifle primers that I had planned to use. I didn't even know there was such a thing as a mil-spec primer for the AR. Are they really necessary? CCI has always had a reputation for being "hard". Has anyone had any experience using their standard small rifle primers in an AR?
Thanks in advance

 

[tiger rag]

I use them and like them. I do believe they are not only harder to avoid slamfire they are also hotter so work your load up with that in mind.

 

[matrem]

Have loaded for & shot ARs for years.Every handload I've used has been with CCI 400 or 450.Have NEVER had a slamfire with them.(IMO zero reason to want / use #41s.)

 

[mallc]

Some odfthe best advise I've read on loading for gas rifles:
******************
Must reading for GAS RIFLE (M1/M14/AR15) type rifles.
http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

I kinda feel like this is required reading. It's the best article on M14 / M1 reloading ever put down on paper. I would pay special attention to the SLAM FIRE stuff as well as powder choices. Mr. Zediker has written several book with Mr. David Tubb on high power rifle reloading and comp. Bottom line is these guys knows their rifles and how not to BLOW them up.

"You'll like this material, and, no fooling, if you have an M14 or M1 you best be paying attention to what's in it befo you hurt yoseff."

http://www.zediker.com/downloads/14_loading.pdf
****************************
Hope it helps.
Scott

 

[Walkalong]

I have shot nothing but Winchester primers in a Mini 14 and ARs with no problems so far.

 

[ir3e971]

I recently built an AR and had the same question.

I have a box of CCI Military primers, and also a box of standard SR primers.

I have been loading both in separate batches to see if I have a problem with the normal primers. No problems so far, though I think I will only use these for plinking loads.

 

[ocabj]

Remington 7-1/2 are probably the most popular primers among AR-15 High Power shooters. After that, it's CCI 400s and BR4s. Wolf SR primers are gaining some popularity.

I still use BR4s for competition and have been using Remington 7-1/2 for practice, but I may switch to the Remington 7-1/2 for competition use as well since they appear to perform equal to the BR4.

 

[FieroCDSP]

I've used the 7.62 CCI arsenal primers in my SKS, and have often felt better that I have, seeing the markings left by the firing pin from just the bolt closing. That linked info is good. Regular CCI primers are plenty hard enough to prevent slam-fire in an AR.

 

[lordgroom]

You want the .308 dies for the K31. With cast bullets I am sizing to .310.

I know you stated your preference for Hornady, but I have no experience with them. Everything I have read says only the Redding dies are spec'ed for the K31, to set the shoulder correctly. Other dies will work but not as well. Specifically, I read yesterday that the Lee dies could be made to work with extra over-camming. Like I said, it was only something I read, not direct experience.

Personal experience:
I have the redding deluxe set and a collet neck sizer with Titanium bushing. It works flawlessly. The redding dies are the best I have used. Very well made. I still like my Lee dies but I do not regret spending all the money I did for the redding dies.

 

[1911user]

The CCI mil-spec primers are magnum small rifle primers with reduced ignition sensitivity. Load them like they were CCI450.

 

[243winxb]

We feel that the single most significant cause to such slam-fires can be traced back to improper seating, not the primer itself.

In 1994, CCI began marketing a line of rifle primers specifically manufactured to meet military specifications for cup thickness and sensitivity. These are the No. 34 (large rifle) and No. 41 (small rifle) primers. Their use in military-type rifles with floating firing pins should decrease the possibility of a slam-fire as long as the pocket is properly prepared, and the primer correctly seated. These are ballistic equivalents to their respective Magnum primers. This extra energy should ensure reliability in virtually any weather conditions, but their real advantage rests with the reduced possibility of a slam-fire.

As important as the choice of primer may be, its proper installation is even more so. Our ultimate goal here is reliable ignition with acceptable accuracy while eliminating (or as nearly as possible) the chances of a slam-fire. http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

 

[rcmodel]

We feel that the single most significant cause to such slam-fires can be traced back to improper seating, not the primer itself.

+1000!

Smashing primers into GI cases without all the old crimp removed is the #1 cause of AR slamfires.

Do the case prep properly, and seat the primers correctly without smashing or flattening them, and you will not have a problem.

rcmodel

 

[snuffy]

Strange that slamfire has not checked in on this thread!

I used to scoff at his admonishments about slamfires,
BUT

after the last range session with my AR I'm a believer! I was shooting some match HP's I had 6 doubles. I had that happen once before, which I blamed on my jewel trigger. I switched to factory Federal-American Eagle tactical XM193, I fired 60 rounds of that WITHOUT a single double bang.

Next trip I'm going to try some more of my match reloads, watching for serious primer hits on the next round into the chamber after normal firing the previous round. Primers are win-SR, cases are R-P on their third firing. All primers are seated to-the-bottom-of-the-cases!

Rifle is a stock bushmaster, all stock bolt/upper parts,(not counting the fore arm and gas block).

 

[ClarkEMyers]

You do whatever you want to do. I use the #41 myself.

Anyone who

didn't even know there was such a thing as a mil-spec primer for the AR

needs to catch up on their reading. I really really don't want to sound like a machine gun.

 

[Jayman]

I had a double because I hadn't set the shoulder back far enough on some of my reloads. Something else to consider. Case prep is crucial.

FWIW, I use # 41s, I have been told that they are the equivalent of the CCI Magnum SR primers.

 

[rcmodel]

I don't understand how that could cause doubling?

If the shoulder is not where it is supposed to be:
*The bolt wouldn't fully lock.
*If the bolt isn't fully locked, the firing pin can't reach the primer.

It is pinned in place in the bolt carrier, and until the bolt carrier is fully forward on the locked bolt, the firing pin cannot possibly fire a round because it can't reach it.

rcmodel

 

[Jayman]

It was a combo of a higher shoulder and a primer that wasn't seated deep enough. Basically the casing was right @ headspace and when the bolt closed, pop goes the primer.

 

[243winxb]

Doubling

which I blamed on my jewel trigger.

If the sear does not engage the hammer, the hammer follows the bolt down, the round then fires. This doubling can also be caused by light loads in the AR15 types that do not fully cycle the bolt.

If the shoulder is not where it is supposed to be:
*The bolt wouldn't fully lock.
*If the bolt isn't fully locked, the firing pin can't reach the primer

True, the angle of the hammer is such that it will not make contact with the firing pin till the round is almost chambered. But it could be a possibility?

 

[Gottahaveone]

Anyone who
didn't even know there was such a thing as a mil-spec primer for the AR
needs to catch up on their reading. I really really don't want to sound like a machine gun.

Well, That was certainly helpful...perhaps the way I discovered they existed was precisely because I was catching up on my reading. And just what DO you want to sound like? Cause now, I have an opinion about the answer to that

 

[snuffy]

If the sear does not engage the hammer, the hammer follows the bolt down, the round then fires. This doubling can also be caused by light loads that do not fully cycle the bolt.

Nope! If the hammer follows the bolt down, the hammer has no inertia to hit the primer. My buddy says the jewel trigger can slip once held by the sear and let the hammer fall with the bolt closed. I plan on increasing the sear engagement to eliminate that possibility. Besides it's just too damn light, even for bench shooting.

 

[243winxb]

My buddy says the jewel trigger can slip once held by the sear and let the hammer fall with the bolt closed

Yes, there is enough delay caused by the sear to let the rifle fire. If you look inside an M16A1 when set to full auto, there is a part that delays the hammer release, much as a light sear engagement would do. I won't go into the light loads here.

 

[243winxb]

Slam-Fires & sear ingagement, not a primer problem after all?

When working with 1911's in 45acp target guns. If the trigger pull was to light and you let the slide slam home on an empty chamber, the hammer would fall, and some times double when loaded. Could this problem with AR's not be the primer, but is really custom triggers set to light or the sear engagement is not correct? Something to think about?

 

[rcmodel]

Two most common types of AR doubling.

Firing pin induced.
(free-floating firing pin)
The first Stoner AR-15 design doubled constantly in testing with mil-spec ammo. The firing pin weight was reduced significantly and primer hardness increased to stop it.

IMHO: This is still the most common problem with reloads doubling because the primers were crushed during seating.

Light single-stage target trigger.
Gun recoils, trigger resets, then you pull the trigger a 2nd. time when it bounces back foreword where it started out.
Sort of the same thing as "Bump Firing", except done from the shoulder.

rcmodel

 

[taliv]

i use Fed GM 205M for High power
CCI 400 for everything else


if you follow the FOUR RULES, you don't really have to worry about soft vs hard primers.

at one time, the cci military primers were fairly cost effective. since they're a lot more expensive than regular primers now, i don't see any reason to use them

 

[snuffy]

if you follow the FOUR RULES, you don't really have to worry about soft vs hard primers.

Ummmm, lesee, that's 1. always be sure the rifle is pointed downrange.

2. Don't point the rifle at anything that you don't want to harm.

3. Be sure of your backstop, and what is behind it.

4. Be sure there's no feds around when you have a slamfire, so you don't get an enormous fine and loose your gun rights.??????????

On the last rule, I belong to a gated very private club. Nobody is fool enough to go report me for an occasional double fire. I'm alone most of the time. But it wastes ammo and ruins groups being fired to test/work up new loads. The second one goes about 4" above the first!:banghead:

I'm going to track down the cause, just because it annoys me. It does nothing to hurt the rifle, since the bolt is locked, but I want it to work right if I would go to another range someday.

I've heard of fitting a bolt/firing pin for a return spring. What's involved? Also are there lighter FP's around that don't cost half of what the rifle cost?