Sometimes My Montana Doesn't Go Bang

[eaglemountainman]

I posted this in another forum. Thought I would ask here also.

Any advice to remedy light strikes on a Kimber Montana 84M? I understand this is a common problem and that Kimber has a longer/stronger firing pin replacement spring. Anybody know if they charge for these or send them out gratis to rectify the situation?
Also, I've read that Wolfe makes a replacement, but some say the spring diameter is too large to fit the bolt channel. Again, anybody have first hand experience?

Before I go the replacement spring route, I'd like to see if I can increase firing pin protrusion. I've read that this is done by first backing out the set screw under the rear of the bolt, then, turning the adjustment screw at the very rear in or out. When I attempt this, the adjustment screw only turns 1/8 - 1/4 turn. That doesn't seem normal, but a can surly be wrong.
Anybody able to help me out? Thanks, Tim

 

[Wapiti1]

They will send you a spring, or at least have been sending them free of charge.

Going from memory;
I'll assume you know how to remove the firing pin/shroud assembly.
To adjust the firing pin protrusion, take the set screw out entirely. Unscrew the firing pin entirely. You may have to fight it a bit since the set screw will damage the threads if set very tight. Screw the pin in, assemble the bolt with no spring. Push the cocking piece forward and measure the protrusion. You want to set it to 0.055"-0.060". Most will bind over 0.060" and IMO, that isn't safe anyway. At some point the pin will start to burst primers and you are just putting more stress on the pin tip.

You'll have to remove the firing pin anyway to get the spring off.

Jeremy

 

[eaglemountainman]

They will send you a spring, or at least have been sending them free of charge.

Going from memory;
I'll assume you know how to remove the firing pin/shroud assembly.
To adjust the firing pin protrusion, take the set screw out entirely. Unscrew the firing pin entirely. You may have to fight it a bit since the set screw will damage the threads if set very tight. Screw the pin in, assemble the bolt with no spring. Push the cocking piece forward and measure the protrusion. You want to set it to 0.055"-0.060". Most will bind over 0.060" and IMO, that isn't safe anyway. At some point the pin will start to burst primers and you are just putting more stress on the pin tip.

You'll have to remove the firing pin anyway to get the spring off.

Jeremy

Thanks, Jeremy. I suspected that maybe the set screw mashed the threads on the adjustment screw, but didn't want to force it in case I was wrong. I'll get a better screwdriver and put some torque to it.
I'm going to give Kimber a call and see what they will do as far as a new spring.
Again, thank you very much - Tim

 

[hereinaz]

I wouldn't adjust protrusion unless it needs it.

Clean the inside of the bolt body and follow any lube instructions, if any. Sometimes a dirty assembly will cause it.

Probably best to get a new pin though.

 

[Wapiti1]

Thanks, Jeremy. I suspected that maybe the set screw mashed the threads on the adjustment screw, but didn't want to force it in case I was wrong. I'll get a better screwdriver and put some torque to it.
I'm going to give Kimber a call and see what they will do as far as a new spring.
Again, thank you very much - Tim

I didn't mention, if you go wolff, the spring is longer than stock and will drag in the bolt under compression. The new Kimber spring is longer too and will also do this. That is normal, and not a problem. Just clean everything, then apply a very light coat of grease to the spring and assemble. It's common on Remington's as well.

Jeremy

 

[Snyd]

Wow. I've never heard of this issue. I've got a Kimber MT I bought back in 2006 and it goes bang every time I've ever pulled the trigger. Is this a newer issue?

 

[ElPollo]

I wouldn't adjust protrusion unless it needs it.

Clean the inside of the bolt body and follow any lube instructions, if any. Sometimes a dirty assembly will cause it.

Probably best to get a new pin though.

I'm with AZ. Suggest you take it apart and clean it first and shoot it again before you change anything else. Are you getting light strikes with multiple ammo types? Could be related to a bad batch of primers too. How long have you had the gun? Honestly, it's pretty rare to wear out a striker spring in a bolt gun. I'm gonna guess you have some gunk built up in there.

 

[Wrench]

I mentioned the same advice on the fire as I will here.....measure the protrusion before you get carried away. It takes about 30 seconds and will make choosing the next step easy.

If you do disassemble the bolt, I suggest working in a gallon ziploc bag. It is impressive how far little parts launch. The bag saves a lot of pissed off.

 

[eaglemountainman]

I'm with AZ. Suggest you take it apart and clean it first and shoot it again before you change anything else. Are you getting light strikes with multiple ammo types? Could be related to a bad batch of primers too. How long have you had the gun? Honestly, it's pretty rare to wear out a striker spring in a bolt gun. I'm gonna guess you have some gunk built up in there.

No gunk. I made sure it was impeccably clean before I posted up my problem. Also, it's not a worn out spring. This has been a well documented problem of inadequate springs installed during manufacture of some 84Ms. Also, the situation has happened with various brands of ammo.

 

[eaglemountainman]

Wow. I've never heard of this issue. I've got a Kimber MT I bought back in 2006 and it goes bang every time I've ever pulled the trigger. Is this a newer issue?

Don't know year of manufacture. Serial # KM36XXX, bought NIB old stock 1 1/2 years ago. Older, unthreaded model with gray stock. I have another, # KM 46XXX that has never once hiccupped.

 

[Marbles]

The Wolff spring works great. It is a tight fit, and rubs the treads going in. However, it appears to have fixed the light strike issue. My inclination (shoddily based on an n of one) is that the only problem with the Wolff spring is behind the eyes of the installer.

 

[eaglemountainman]

The Wolff spring works great. It is a tight fit, and rubs the treads going in. However, it appears to have fixed the light strike issue. My inclination (shoddily based on an n of one) is that the only problem with the Wolff spring is behind the eyes of the installer.

Thanks. If it comes down to it, I'm gonna see if Kimber will supply one of their longer replacement springs first. If that doesn't work out, then I'll give Wolff a shot.
But before I replace anything, I'm going to set up the protrusion at exactly .055 and run the gun a bit to see if that remedies the situation.

 

[Wrench]

So what is the protrusion?

 

[Marbles]

So what is the protrusion?

It is how far the firing pin extends past the bolt face. To little and you don't get a reliable bang. Too much and you get pierced primers and hot gas in your face and perhaps fast moving gun parts.

My protrusion was around 0.050-0.055 from the factory, which is in the acceptable range, so I decided to replace the spring. I say around because I was unable to get an exact measurment due to the tools I had on hand.

Edited to correct for an error in memory.

 

[eaglemountainman]

So what is the protrusion?

.047 - .048

 

[Wapiti1]

Wrench is right on this. Try the spring first. 0.045" of protrusion is normal on several actions and plenty unless you have a super loose chamber or really short ammo.

Jeremy

 

[Marbles]

So what is the protrusion?

I completely misread your question. Please laugh at my expence. My brain apparently deleated the word "the" from your post.

 

[eaglemountainman]

Wrench is right on this. Try the spring first. 0.045" of protrusion is normal on several actions and plenty unless you have a super loose chamber or really short ammo.

Jeremy

Yeah, huh? Everything I've read so far says .050 - .055 was optimal....

 

[762 ULTRAMAGA]

This sounds a lot like an excessive headapace issue, I've had the same thing happen and after measuring the shoulder on fired cases I was getting .015 growth!
Get a shoulder gauge and take some before and after measurements

 

[Wapiti1]

Yeah, huh? Everything I've read so far says .050 - .055 was optimal....

Depends on the action and firing pin size. Mausers like 0.045-0.050. M17 enfields do as well, but P14's do better at 0.045 due to the skinny pin they have. They'll pierce primers if you go long with them. Remington's depend on the firing pin size you have. There are fat ones and skinny ones available.

One thing you'll find is that there isn't a spec.

Jeremy