Help with match chamber on a Kimber

[Jim Franklin]

I was hoping someone could give tell me how much the bullet should be pushed into the rifling on my CMP Kimber rifle. I am suspecting that the chamber is too tight. I keep getting miss fires and I am thinking that the cartridge is not seated properly and when the firing pin strikes, the force from the firing pin is being absorbed when the cartridge is seated forward. The rifle will fire 100% of the time if I recock the bolt and try again. I have tried different ammo with different rim thickness and still miss fires. Extracting an unfired round, it looks like the bullet in pushed into the rifling about .100 inch. Extracting a miss fire shows a light strike on the rim. A fired rounds shows a well indented strike. Any thoughts? TIA Jim

Information

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[Gib]

Jim,
Have you disassembled the bolt and cleaned it?

[Jim Franklin]

Yes. I have had the bolt apart several times. I cleaned, lubed, polished, took .8 thousands off the striker face so that the firing pin extended more into the cartridge, stretched the spring, adjusted the trigger, put a lighter spring in the trigger assembly to reduce any drag on the striker, and tried different ammo. Maybe it is excessive head space. Maybe the chamber. I am scatching my head on this one. Jim

[Bob G]

I teach a Junior Shooting class at one of the Rod and Gun Clubs that I belong to. We have 7 Government Kimber 82G's. We often get misfires. I have taken the bolts apart and machined the firing pin a few thousanths to give a slightly longer pin travel to hit harder. The spring is about as large a diameter spring wire as can be used. I made a spacer to add length to the spring so that it is as long as possible to strike harder. That worked the best. The misfires were reduced by quite a bit. I think the problem with the Kimbers is the very short pin fall.

[Too Much Coffee]

Match chambers are tight. All rounds chambered should engage the rifling. Extracting an unfired cartridge should be very difficult, sometimes having to use a rod to push it out.

Headspace controls how far the shell is chambered. Have you tried to push/seat the round by hand in the chamber. Push by hand as far as it will go? This will insure that the round will not travel forward and lose some of the firing pin force. It could be headspace on the large end and weak fring pin spring.

Gage some rims and use rims that are .042 and +. See if it still happens? Try the spring spacer as suggested above. Is it a CMP/Govt. Kimber?

[Devil Dog]

Make sure your trigger "over travel" adjustment is enough to not bind the striker. Is the chamber clean. As T.M.C. said above... make sure a round will chamber fully by hand. Are the any marks on the sides of an ejected case (fired or not)? What did you lube the bolt with? Is the headspace okay? Have you tried other ammo?
You better figure it out...you can't send it to Oregon.

[john w]

I do not think it is a chamber problem. DO NOT lube the firing pin channel!. Wipe the firing pin lightly with some very light oil like wd40 or pb blaster penetrating oil. You do not want to slow the firing pin down and a light grease or heavy oil will slow it down. If this is happening with the same type of ammo switch and see how it works out.
I would also make sure the firing pin has full travel forward but from what you are saying upon re-cocking it hits harder thats why i think the problem is with the bolt. As mentioned make sure your trigger sear drops enough as to not put a drag on the firing pin or bolt.