I took my Montana/Obermeyer featherweight barrel build to the range for a quick test fire and I got some strange misfires. It would only happen when a round was in the chamber. I would pull the trigger and I could feel a slight “click”, but nothing else. The firing pin was still cocked. As soon as I began to lift the bolt handle, the firing pin would break free and fire.

A couple of times I got light primer strikes but they would fire on the second try.

I never got a hung firing pin on an empty chamber.

Anyone ever see this?

I’ll strip the bolt down tonight and see if I can find anything obvious.

Thank GOD I always kept the muzzle down range and the round simply hit the berm.

Consequently, I spent more time troubleshooting the issue and little time shooting groups. Still, it held about 1” at 100. With hunting loads.

Tony.

This message has been edited. Last edited by: benny6,

You are more of an expert than I will ever be but I have an idea that some burr or object in in bolt to cause a bind and the a fire when handle is touched.
lite strike is a puzzler ,if the gun has been working with same ammo.
Stay safe,slam fires and hang fires I know of.
Seem my handle,sticky firing pin shot my refrigerator twice .

The gun was just recently built and probably had less than 10 rounds down the barrel. The action was probably made in the early 2000’s. I may try to polish things up where the firing pin is held captive by the sear (not sure of the terminology here).

Tony.

My first stop would be the bolt and firing pin channel.

Benny,I forgot to mention my experience with a Winchester 7 mm about 35 years ago.
lite strikes,plus delay in when you pulled the trigger.
This was a new gun I had bought from wal mart store when they were closing out that store's firearms.
Pulled the bolt apart,the thing was caked with a huge amount of rust on the inside.
It looked as if it had been exposed to blueing salts.
Not saying that is the problem but rather my experience with a brand new gun.
I got it corrected and sold it ,it was a good shooter but I preferred Remington like the rest of my hunting rifles

Let's think about it. Dry fired empty chamber fine, striker hangs when loaded.

I am sure you have but I'd check headspace to see if it is short chamber and preventing bolt from fully closing. I'd also mic the ammo and compare to SAMMI specs. If those are good I'd then see if it was some clearance issue with the extractor cut that when there is a rim under it is preventing the bolt from fully closing. Might be a burr in there or something.

Where I am going with this is something is preventing the bolt from fully closing when loaded. When you pull trigger you've released the sear, but the striker is being held back (like it is supposed to if the bolt isn't fully in battery) - but barely. When you tap the bolt handle it breaks free.

Use some empty cases to see if you can recreate the scenario.

I think I figured it out. The firing pin cocking cam seems to have been catching on the U-shaped firing pin tail relief cutout on the receiver. I beveled and polished both edges and will test it out again.

It makes sense. When there’s an empty chamber, there’s more slop in the bolt and the firing pin base isn’t held in place as firm as when there’s a round in there.

When there’s a round in the chamber, the bolt lugs are firmly seated and the back of the bolt and there’s no play at the back of the bolt so the firing pin cocking cam gets hung up. As soon as I apply pressure to the bolt handle, it’s enough to break the firing pin free.

Headspace is 1.635” and my handlods are sized around 1.628.”





Tony.

This message has been edited. Last edited by: benny6,

That's unusual.

So I took it out for a test fire yesterday after beveling and polishing the calming surface and the hang fire is gone. However, I had 12 misfires out of 19 rounds. Click, no BANG. Dimples were light.

I took the bolt apart to check firing pin protrusion and after removing the firing pin spring, I observed the firing pin travel through the bolt. It hangs up significantly and does not move freely through the full travel. Either the firing pin is bent or the hole for the firing pin shank is undersized as it reaches full travel.

More to come.

Tony.

Could the firing pin spring under compression be binding or expanding outward in the channel?
Any gaulding on any part of the spring?

The spring has been removed from the equation and the bare pin binds when it should slide freely.

Tony.

That stinks- basic Mauser action you’d think they’d have that down.

Just an update. The firing pin was bent and binding in the bolt. I ordered a new firing pin, Wolff extra power firing pin spring and a new cocking piece. Total was about $70.

As a reminder; this receiver was made in 2003 and was only assembled last year. Its still in the white. There's no telling what has happened to the receiver in those 14 years until it was built, so any issues shouldn't be reflective of what Montana Rifle Co puts out now.

I'll be taking the barrel off and sending the barrel and receiver out to be nitrided.

Tony.

Well, I received my new firing pin, cocking piece and an extra power spring from Montana R.C. and got them installed.

For those of you that don't know, the firing pin is fully adjustable when new but once you have it set, you have to grind some of the threads off to leave room for the safety shaft. The lock screw, red loc-tite and the safety shaft ensure that the pin never moves from that position ever again.

I set the firing pin protrusion on the long side (checked with a FP GO/NO-GO gauge) and got everything locked in place. Installing a new cocking piece requires that you fit it and remove some material to make room for the safety to engage. After all was said and done, my firing pin fit nice and smooth with no binding at all, is set for good protrusion and has a stronger firing pin spring.

I went out over lunch to throw some downrange and it fired everything I threw at it reliably. I fired some home made M80 FMJ with CCI-250's (hard military primer), some 165 grain Accuracy-bonds with Remington 9-1/2 primers and some Federal 168gr FGMM.

This trip was mostly for reliability testing, and not for accuracy testing. I fired around 30 rounds and toward the end, I spaced the shots by about 2 minutes since the barrel was really warm.

End group was about 1.25" or so. Not bad for a featherweight barrel that had a lot of rounds through it.

Now I'll pull the barrel and send off the receiver and barrel to be bead blasted and nitrided. After that will be load development, accuracy testing and trigger tuning.



Thanks for following.

Tony.