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.
