Friends,
I run into a very perplexing and annoying problem.
We have a rather large audience here,so one should get a few voices of experience that have run into this:
rifle is a custom built 300RUM with a Nesika action.
I have been working on developing the proper ammo for this weapon and settled for 92gr Retumbo behind 180gr Tx bullets.Shoots a horiz string of about 1/4" at 100y by 2 " horiz,=probably wind or me.

Now I tried it the next am at 9:00 am, temp around freezing: I get a misfire,small dimple in the primer.I repeated this phenomenon .Delivered the rifle to 2 gunsmith
first polished the firing pin and "opened up" the hole in the bolt
2nd smith found a slight resistance with the Jewell trigger,straightened it out and now the Jewell trigger wont work
He gave me an emergence Remington trigger assembly.Sht all day with it,only the next am- same story.Misfires.
Tried different primers - no change
Took the rifle home, placed the bolt into my frezer for 10 mins: big misfire, hardly a dimple on the primer !

that pretty much defines the problem, the spring is strong and the bolt free of grease and dirt by inspection of the smith.

What a let down: develop ammo and take the rifle on top of the cold mountain range only to have it fail because of this temp sensitivity.

I shipped the rifle back to Nesika,now owned by Dakota I hear.
It sounds like the metal shrinks in cold temp and does not allow the pin to strike with sufficient force.
Could be a spring that is to blame or an overly sensitive pin?
In any event - pretty depressing and to my interpretation - shoddy material selection.

I failed to mention: headspace was measure and proven correct.
Firing pin comes out of the whole (60 deg temp) the correct amount.

thanks for sharing experiences

Sheephunter, if cold temps are the exacerbating factor, than I would agree with your thought that something is contacting and binding. It sure sounds like a spring/grease problem to me. I've seen this often, and in every case, cleaning the heck out of the bolt, and 'lubing' with something dry like Tef-Dri or graphite cured the issue. I understand that your smith(s) said the bolt was clean and not a grease issue, but that sure sounds like tha answer.... some of the really knowledgeable folks here should have better intel, my other thought would be that the firing pin needs to be bushed, not just the aperture opened up, I'd sure want a new speedlock spring in that bitch!

Good Luck--Don

I had a Sako L-461 that did the very same thing.

The hole in the bolt shrunk in the cold and didn't allow the firing pin to go thru easily. The hole shrinks faster than the pin and additionsal clearance was needed.

You said one of the smiths worked on that but I suspect he didn't get enough clearance yet.

You need a set of gage pins and an OD micrometer to accurately measure the clearance.

Have the clearance compared to other rifles you own that work well. See if that's the problem.

Clearance between the firing pin and the inside of the bolt body?

Frankly I'd look for rub marks on the outside of the striker spring....

And the cold temps shrinking the bolt body around the spring likely makes the problem worse.

AllanD

In my 30-06 Sako Finnbear had a firing pin hang up problem in cold weather to correct it I used Break Free in the bolt took care of the problem immediately.

It should be fairly easy to check the firing pin and hole. Freeze the bolt assy and drop the firing pin into the cocking notch and have a look. Second I would try a sub zero grease like the Dow Corning 33 (-100 to -400 degrees F) and maybe take a second look at the spring, and how snug of a fit is has on the firing pin.

I had a remington spring that would strike the primers with no force.You could feel it when dry firing,the energy on impact was never the same.A Tubb spring solved that problem but I trust my Sako more than anything.She hits really hard with that factory spring and pin,with constant energy.I would trust the Sako if the rifle would be out in the cold for a long time.I have your problem with my double shotgun.It barely strikes the primers in the cold,whereas my partners Beretta semi-auto has no problem.In the cold,everything slows down.So for it to work it has go fast and hard when it is warm.

Isn't that action you have suppose to work better than others?

I am familiar with this problem. It has to do with the action and the trigger mating up to each other. Several guys in the benchrest community have had this problem. As I recall it has to do with the cocking cam configuration that make the Nesila's easy to open the bolt. This was done so the gun isn't disturbed so much in the bags when match shooting. I remember Glen who founded Nesika tearing the Jewell triggers apart and modified them to make the gun go bang. If you call BAT Machine and talk to Tom he can explain this in detail. I know this is the problem. Call Tom at BAT and get the real skinny. It really doesn't have anything to do with the size of the hole in the bolt face. You have a Jewell trigger. I know this is the problem. I consider Glen who founded Nesika a good friend but I would never own a Nesika because of this.