Slam Fires and semi autos


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rikman
April 28, 2011, 05:31 PM
Do any of you specifically use primers for semi autos, ie, CCI #41(5.66mm) and #34(7.62mm) to avoid slam fires while the action is cycling?


Just learned about these primers from CCI's website and another forum/video

Thanks
Rikman

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ADKWOODSMAN
April 28, 2011, 05:33 PM
If the primer is seated correctly, just below the surface of the case head no slam fire can occur provided the firepin doesn't have a problem.

MEHavey
April 28, 2011, 05:39 PM
Absolutely.
CCI for all my gas guns: Colt AR, M1, and M1A

In my case I use CCI BR2 and BR4 (LR & SR match primers) for stick powders, and CCI Magnum primers for ball powders.
Hand prime w/ Lee Autoprime to feel it going home/stopping.
Visual quicklook for below-flush seating.

Cheap insurance.....

See here:
http://www.sksboards.com/smf/index.php?topic=56422.0

Wolfman Bill
April 28, 2011, 05:48 PM
Afternoon Rikman

No I donít but both my ARís leave a small dent in the primer if I allow the bolt to slam shut on a round in the chamber. I use standard CCI small rifle and havenít ever had a slam fire but those primer dents look like it might be possible (especially with a softer primer than CCI)

rikman
April 28, 2011, 06:01 PM
THanks for the replies and discussion guys! Mehavey that is a great article/reference on primers! Wolfman Bill,in the video that brought this to my attention, he specifically cites that the risk may be when the action cycles not necessarily when you release the bolt??? Also CCI's site specifically references #34 & #41 for semi autos versus BR@ & BR4....for a little more safety/insurance against a slam fire

see here:http://www.cci-ammunition.com/products/primers/primers.aspx?id=30

Rikman

gamestalker
April 28, 2011, 06:04 PM
That's an issue with the FP mechanism. I've bought brand new firearms that produce small dents in the primer. A little fine tuning, maybe a little heavier spring, or maybe the FP needs some tweaking, too long by a thou or it's stopping too shallow, usually easy to tune issues. Either way it's a problem with the firearm, changing primers isn't going to eliminate the dents.
I once had a new in the box 9mm and a Rock River .223 that would put some pretty deep dents in the primers, but they never produced a slam fire. Did some minor work on them and solved the anoying occurance.

USSR
April 28, 2011, 06:14 PM
I use Winchester LR primers exclusively to feed my Garands. I also use a primer pocket uniformer to ensure that there is no problem with primers not being able to be seated deep enough. Never had a problem, and don't anticipate any.

Don

Wolfman Bill
April 28, 2011, 08:27 PM
THanks for the replies and discussion guys! Mehavey that is a great article/reference on primers! Wolfman Bill,in the video that brought this to my attention, he specifically cites that the risk may be when the action cycles not necessarily when you release the bolt??? Also CCI's site specifically references #34 & #41 for semi autos versus BR@ & BR4....for a little more safety/insurance against a slam fire

see here:http://www.cci-ammunition.com/products/primers/primers.aspx?id=30

Rikman
Evening Rikman

That might be on some but on my 2 AR’s I get very little primer denting when the round is stripped out of the magazine. Probably due to round slowing the bolt action slightly.
When I get the biggest primer dent is either single loading and dropping the bolt with the hold open button or when I insert that extra round in the chamber then dropping the bolt before inserting a full magazine.

MEHavey
April 28, 2011, 11:58 PM
CCI's site specifically references #34 & #41 for semi autos versus BR@ & BR4.

Lawyers & sales reps... (Maaaybe)
But let's check....

`Any match shooters here (Slamfire?) have -- or even hear rumors of -- problems with properly-seated CCI BR's and/or Mag primers ?

rikman
April 29, 2011, 12:11 AM
Mehavey,

Maybe you're right, lawyers. I just re read that article you gave me in the link. BR4 are ok for AR. It does say that it's more of a potential problem in SKS/AK Rifles. It also says CCI tech doesn't recommend Standard small rifle primers(#400) for the AR because of "thinner cup".(.005") I loaded about 6 with that primer in an NRA reloading course and had no problems. CCI'S site says it's not just a primer issue , but that could with headspace issues, primer seating depths, etc you can have problems and therefore recommend the harder primers...

GW Staar
April 29, 2011, 12:53 AM
Gentlemen:

I wish to share with you my only slam fire experience and what I learned from it.

Obama November (two years ago) I bought a Remington R25. It was a planned purchase (Christmas present from my wife) done a month early because AR style rifles were disappearing so fast, December would find gun shop racks empty. Anyway it was a Merry Christmas in spite of Obama.;)

Up to then the only semi-auto I owned was a Ruger Mini-14.....never a slam fire or even a misfire in 30 years....and nearly only reloads shot.

The Remington (really a DPMS .308 in Remington mossy oak disguise) was a different matter.

I've been reloading a lot of LC military brass for it....all of it has performed as expected so far....except for one....yup...slamfire!

Obviously that started a serious investigation.

First, background information about those reloads:

Another purchase I made in that period was an RCBS Pro 2000 after 40 years of reloading on a Rockchucker.
I know the importance of primer depth, proper bullet seating and proper headspacing. I also use the proper gauges to make sure my sizing die sized cases so that headspacing is right for my rifle.
All of my reloads to that time were thus sized and checked.
The RCBS Pro 2000 has a very useful and positive feature I like that allows me to set primer depth exactly the same every time. I used the feature to make sure each and every reload had the primers seated .007" below the case head rim. (I used CCI's, but not military spec ones)
The only less than fun step in making those reloads was removing the primer pocket crimp. The LC brass was old (1968) from a national guard rifle range (no machine gun brass) It was hard brass and more difficult to process than newer LC I've used. My RCBS swager actually sheared a tiny brass ring off the crimp area on many cases rather than swaging it back where it came from, and also the pocket seemed to spring back some as well and make primer seating harder than it should be. I was careful to make sure those tiny brass shearings were removed from the pockets before I primed.
Since uniformed pockets are necessary for the Pro 2000 to seat each primer the same depth, my next step was to uniform the primer depth. The "spring back" caused problems with the pocket uniformer binding in the pocket, so I was forced to additionally ream slightly the crimps until the uniformer went in without binding, and the primers seated more easily.


Next the investigation following the slamfire:

First, I checked all of the remaining un-shot rounds in that batch of 500 reloaded to that date, using the same LC brass. I did find one round with a high primer. Thinking evil thoughts about a certain progressive press's primer seating feature, I pulled the bullet, and slowly pushed the un-shot primer out of the pocket. Examining the pocket and measuring its depth, I found that it was NOT as deep as it should have been. Using a bent pin I removed an embedded sliver of brass around the outside edge of the pocket bottom. I had missed a sheared ring of brass from swaging and the uniformer must have reached the loose ring and just spun in the hole. I would have thought the lack of brass trimmings from uniforming to only mean the pocket was deep enough already.

Second, I examined the brass that had caused the slam fire and found the same thing. So out of a 500 round batch I managed to miss two sheared rings of brass. All the rest of that batch has since been shot. No other slam fires.

My conclusions:


I will not swage any more of that old LC brass. Reaming will not cause that problem.

The CCI primer metal is sufficiantly hard that the RCBS Pro 2000 doesn't easily crush CCI cups. IOW the seating stoke felt the same while bottomed over the sheared brass in bottom of the cup (leaving the high primer) as the other finished strokes that properly seated primers .007 under. So its critically up to me to make sure the pockets are indeed uniform.

Oh, and one more thing...I learned that checking only the first 200 for high primers is asking for it! And I certainly knew better!:)


Hope this helps someone to not experience their own slamfire.:D

rikman
April 29, 2011, 01:01 AM
GW,

Glad you're ok first off ....and thanks for sharing your experience with us..

Rikman

GW Staar
April 29, 2011, 01:49 AM
GW,

Glad you're ok first off ....and thanks for sharing your experience with us..

Rikman

You're welcome.

Slamfires are only dangerous if they are pointed somewhere besides at the target. They just scare the hell out of you....and raise eyebrows all around. Not to mention it's very embarrassing too.:o And it's certainly a valid reason to NEVER point your gun elsewhere but downrange, while you got a loaded chamber and/or magazine in your gun.

Out of battery ignition, however, is the really dangerous one that destroys guns and worse.....and is usually caused by headspace problems, unless the primers are ridiculously high and prevent the bolt from closing. Think most people would notice that.

MEHavey
April 29, 2011, 06:54 AM
Good sleuthing GW. The only thing worse the slamfire itself is not subsequently knowing what caused it. I admit to a certain amount of paranoia myself and have therefore always used handpriming as a means to force immediate visual/feel check of each primer going home.

Like you, I have taken to using my drill-mouted Lyman pocket uniformer each and every time I first load a case, and then each and every time I reload that case. I've also taken to using that uniformer--rather than a pocket swager--on my HXP brass for the M1.

I really, really like the resultant ..."uniformity" :D

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