Kimber 84M help ?????

[chet]

hey guys! It's been waaaay too long since I've posted here! anyways....
I won a Kimber 84M classic in 308 win at a banquet, It's a special edition made for the Mule Deer Foundation. #50 of 100. It's absolutely gorgeous! Extremely light weight! I love the Model 70 safety and control round feed and the model 700 floor plate... best of both worlds in my opinion. I was gonna save it in the box un-fired to see what it may be worth someday....... two years later I decide it needs to be shot!!!!! HELL YEAH!!!

So on to my problem.........
the third shot during barrel break-in.... CLICK no bang? :shock:
I ejected the cartridge, primer was hit. Faulty primer? nope, second try BANG! WTF????? In my 15 years of reloading I've never had a missfire.
Shot number seven CLICK no bang :evil: WTF! I didn't eject the cartridge, just cocked and locked and slapped the trigger... BANG!!!
The next three went off just fine. and thats where I have stopped in the break-in process (shoot one, clean one for ten shots)
So.... I've pulled the trigger 12 times and have had two mis-fires, at this point I'm assuming the primers are fine, i suspect headspace issues.

A headspace issue can be caused by two things: an oversized chamber or an undersize case. I'm using nosler brass, and they chambered fine so I did not re-size them before loading. So using my bullet comparator, I created a neat little headspace guage to compare the fired and un-fired cases. The smallest of the unfired cases measured .003" smaller than the largest fired case. The average difference between new and used was .002". This seems perfectly fine to me, but honestly I'm not sure. Is this normal clearance? I was actually hoping it was a slight headspace issue, I figured once I fired all 50 cases, I'd just neck size and the problem would be cured until the next batch of new brass was needed (which would take me several years). I wish I would not have fired one of the two misfires for measuring purposes, if it happens again I'll be sure to save it for inspection, but at this point I have measured all of the new cases anyway and they are all near identical.
So.... any input on this?

Next up is firing pin issues:
Kimber rifles have an adjustable firing pin, the pin itself can be screwed in or out via an access hole in the rear of the bolt. Factory protrusion was .058. I was able to get it to .060 where it was mechanically bound and can't protrude any farther. trying to turn it out further actually lessens the spring pre-load. so I took it back to .059 to make sure the spring had plenty of snap. So basically, the less protrusion, the more pre-load on the spring... which is more desireable? .035 with extra oomph? or the more protrusion the better? the dents in the primer seem shallow compared to other rifles, which is why I suspected a headspace issue.
Wolffe gunsprings actually makes a stronger spring for this gun, but it is .046" larger OD (so it might drag inside the bolt) and .030" larger ID (which might allow the spring to bend and not compress in a straight fassion). Both of those problems would cause major lock-time issues, something I cannot afford :wink:
So Wolffe is sending me the spring at no charge to see if it might do the trick...... They said I can call back and pay for it if it works!
How about any input on this?

Am I completely stupid and overlooking something simple?

I really love the feel of this little gun 8) and accuracy seems to be excellent from what I've seen so far, of course this light little barrel will heat up quickly when I start shooting groups.

 

[DrMike]

Doesn't sound like a headspace problem, and the firing pin looks to be fine. I would first check to ensure that the primers are fully seated in the primer pocket. Your description leads me to suspect this as the cause of the misfires. It happens from time-to-time.

 

[chet]

So the firing pin would actually have to finish seating the primer in order for the primer anvil to provide enough pressure for detonation........
of course the primers all end up in the same place during the firing process (flush against the bolt face) that makes for a tough confirmation.
And if I have another mis-fire due to this, the primer would have been relocated by the strike of the firing pin, again making for a tough confirmation.
Nosler brass has been primer pocket uniformed, and I primed them with CCI200 in a hand held Lee Auto Primer.
Should I not fully seat a primer and see what happens?
I always feel over the case headstamp with my thumb but have never actually used a primer depth guage...... all felt normal, but after all, how accurate is my thumb? :lol:

 

[DrMike]

chet,

I've had situations where I could swear that I fully seated the primers, but they failed to fire. If the firing pin spring is somewhat weak, it will not detonate as it must first seat the primer. The only other time I actually had this problem (excepting a couple of lots of faulty primers) was with a new rifle that had a rough spot on the firing pin. Smoothing the firing pin resolved the problem. I would first attempt to ensure that the primer is fully seated. Usually, visual inspection is sufficient to ensure that you have fully seated the primer. Unless you have a lot of brass with pockets that are a few thousandths deeper than specs, you should be good to go with a visual inspection to ensure that you are fully seated.

 

[Ol` Joe]

While you`re playing with the springs wipe out the inside of the bolt and make sure there isn`t any gunk or metal shavings from manufacture that might be inhibiting the works. Look for a burr on the pin body too.

 

[chet]

Inside of the bolt looks fine. Shoulder of the pin looks good too. I'm anxious for the new spring to get here..... I have some testing ideas as to how to test the amount of energy coming from the firing pin.
On a side note:
the "snap" sound from dry firing sounds more like my 10/22 than any of my Model 70's..........

 

[longwinters]

I'd try some factory rounds....just in case. Then I would be doing some searching on the net for people with similar problems with the Kimbers. Maybe call Kimber and see what they say. How about cleaning it with brake cleaner or something. Maybe some gunk in there.

Long

 

[big rifle man]

Dr. Mike, (or anyone familiar with a kimber bolt disassembly). I've never taken my Kimber bolt apart. any suggestions on disassembly. I own a Kimber Montana . Haven't had any problems but would like to take it apart to clean. I called Kimber in regards to instructions but their comment was to "Send the rifle to them and they will clean it". I don't want to have to take a scope and mounts off just to send it to them for a bolt cleaning.

 

[Charlie-NY]

My buddy just recently bought a Kimber 84 in .308. He also bought a couple of boxes of Win ammo with the 150gr XP3 bullet. At the range several rounds did not go off - very disturbing for a new, high quality rifle and factory ammo.

I gave him some of my .308 handloads and every round fired without any problem. This made me originally assume that the Win factory ammo was at fault. However, I took some of that ammo, including those that didn't fire in his rifle, and fired every single round through my .308 rifle without any misfires.

At this point, I can only conclude that his problem is caused by the combination of a weak firing pin strike coupled by some hard factory primers. My buddy only shoots factory ammo so trying something different may solve the problem but, unfortunately, he really likes the XP3 bullet.

 

[chet]

OK, so I'm in the second stage of break-in with this rifle (shoot three, clean, shoot three, clean, ect, ect) ... Prior to shooting three today I played with the firing pin protrusion. I took it back to .045". My goal was to give the firing spring more pre-load in an effort to achieve a harder primer hit. It appears to have worked. All three shots fired, and all three primer dents appear to be more aggressive than the previous rounds fired.
I'm still looking forward to playing with the Wolffe spring, as these primer dents still seem a tad shallow compared to my other rifles. But at least I feel like I'm on the right track. It was only three rounds, so it doesn't really prove anything, but just visually looking at these primers it kinda makes sense...... and it's nice that it's happening during break in because none of these shots even matter.... I'm not shooting for groups or testing for pressure, just throwing copper down the bore. hopefully it's all cured by the time I start testing more important loads.

I thought about buying a box of factory ammo to try, but that's like catching a cutthroat trout on a fly you bought from wal-mart :lol: I just gotta roll my own! 8)

Oh and another thing, Kimber wont help me because I didn't purchase this gun from a retailer and because I implied that I just wanted to fix it myself........

 

[chet]

I got the spring..... it doesnt work.... to large of OD....