Blown Primer
Posted: Sat Dec 04, 2021 4:26 am
Thought I should do an update on the blown primer issue I had. It really had me puzzled. I'm a very meticulous reloader and don't take chances, heck I even weight each and every load on a RCBS 10-10 scale and use a trickler ..............on every round I load. Time consuming I know and not always necessary, but that's how I started reloading and I have not changed since I started around 1977. So this blown primer, a first for me, really was getting to me.............and then it dawned on me. I was shooting a Kimber Montana in 223 of which I have 2 of them and a Kimber Longmaster in 223, all three gave me light strikes at times so changed the firing pin springs to a 40% heavier spring that Wolf Springs offers. Though's of you who have Kimbers probably no where I'm going with this. 
Firing pins in Kimber 84M rifles are adjustable and when you change firing pin springs you have to adjust the firing pin so that the pin has about a .055" protrusion outside the bolt face. This I did on all three of the rifles using a Mitutoyo Digital caliper. I decided I had better recheck those firing pins and sure enough, the rifle that had the blown primer had a protrusion of .060". 
Not sure how that got by me but there it was. 
The other 2 were right on the money.
Needless to say, I now feel better since it was not a reload error.
Firing pins in Kimber 84M rifles are adjustable and when you change firing pin springs you have to adjust the firing pin so that the pin has about a .055" protrusion outside the bolt face. This I did on all three of the rifles using a Mitutoyo Digital caliper. I decided I had better recheck those firing pins and sure enough, the rifle that had the blown primer had a protrusion of .060". Not sure how that got by me but there it was. The other 2 were right on the money. Needless to say, I now feel better since it was not a reload error.