OK this simply little project is driving me nuts.

I have a Mark X that someone had installed a FN style shroud and safety. I was moving the barreled action to a new old stock that had been opened for a side safety. So when I had the barreled action re-blued I had a new smooth shroud blued to match. So yesterday I started the swap. I had not opened the bolt since I had it blued. I couldn't lift the bolt. Had to hit it with a rubber mallet to open. Figured it needed smoothing.

So swapped shroud and went to reinstall. It went on the bolt just fine. But the cocking piece was a military style and the gap didn't want to function with the MKX factory adjustable trigger. So I did find a spare smooth bottom cocking piece got ready to install but it was for the MKX with the shorter pin fall.

So went back to the part box. Quick fix I decided to pull the cocking piece from the action that I keep to check inletting. Put it on the firing pin from the rifle and it stopped 1/4 turn from going in. So used the full pin, spring, cocking piece and it worked fine. Did have to hit the feed ramp and cocking piece to get a smooth bolt lift.

Went to put the old FN back in the bolt and it stopped 1/4 turn short.

The pins are different. I'm confused what I'm missing. This what the old and new assembly look like. Why won't it go back in?

You do have the most wonderful way of confuzzling stuff! Strip them down to bare nothing. Screw in the shroud. Keep adding parts and trying it till you find the offending party. When you do, throw it against the wall, beat on it and - - - - - - - Well you get the idea.

LOL

Sometimes the cocking pieces do not turn in on all firing pins; that is more common than you think. You can put layout dye on the firing pin and then file to fit the cocking piece,
Now, your left firing pin is of the old type, without the internal safety interlock.. The Mexican 36s used this type of pin, but they are not full 98 length.
If the firing pin with the interlock feature won't fit into a bolt, then it is not cut for that feature. That is the lugs on the boss, just rearward of the FP tip. I thought all MK10s had this
feature. Also, check your cocking cam on the bolt, and in particular, the cocking piece. It is supposed to cam the FP back, out of the internal bolt/firing pin recess.

Or use Speer's method; hit it with a BFH until it either works, or it is smashed beyond recognition; then get a new one.

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You do have the most wonderful way of confuzzling stuff!

I would really hate for you to get bored with easy $hit. Wanted to remain honest and not edit the intermediate screw-ups.

I have no clue why a MKX bolt had the strange firing pin in it. It came in one of the Ackley barreled actions sold by the company that bought him out. The safety holds the pin back far enough that the cocking piece doesn't contact the bolt.

While I'm going with the MKX parts on the right it has me curious as to what is going on. So will do both the add parts until it fails as well as blacken the boss to see if it makes contact. Might also pull a FN bolt and see if the appearance is the same.

Last to feel safe will stick a gauge in it to insure headspace is correct and someone didn't just stick crap together. The action is a MKX but as I said no clue on the FN parts.

Seems I'll jack with anything to keep from working on finishing the basement.

You have several minor compatibility issues going with that arrangement. Mauser parts were not interchangeable, never were, and for the most part, never will be. It IS surprising how often I have issues with parts fitting. Not surprising when you start adding up the years, factories, arsenals, countries, models, modifications, rearsenals, etc that were done to them over the last 118 years.

I have 4 Oberndorf actions on the bench, two matching numbers. One produced in 1899, one produced in 1903, one produced in 1906, and one produced ~ 1914. I cannot swap the bolts on any.

Like was mentioned, start from the beginning and build up. You will see what the error was.

If you want detailed help, post pictures of your bolt along with the original parts.

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You have several minor compatibility issues going with that arrangement

Yep.
I think I've gotten away with it or been lucky in the past.

So after in the morning will pay around and see what the issue is. As it stands the MKX bolt assembly works perfect. So will use the other as a learning experience.

Thanks guys for your input.

Well did the speer method Took both assemblies apart and the firing pin on the FN was about .03" longer. The length was from the boss forward.

Tried the short pin and still would not screw in.
So Shroud by itself screwed in. With firing pin and shroud had issues. Removed the pin and cocking piece and swung safety to full on and the shroud would not install. Removed the safety and you can see where the safety is making contact with the rear of the bolt.
So I should have left things alone.

Decided to pull an another FN bolt apart to see how it functioned. To see if there was a second notch to allow the safety to log the bolt etc. Pulled the shroud and the rear of the bolt body looked just like the MKX bolt. Then pulled the safety and felt something hit my shirt. I had FORGOT it had a ball bearing and spring.!!!!!!!!!! So after 1 hr I found the ball bearing but the spring is still missing in action.

So I found why the old assembly wouldn't install. BUT, how in the world the word did the previous owner get it together without the safety holding the pin back. Also how did it work period.

OH well. In with the MKX shroud, pin, spring and cocking piece.

If I can't find the safety spring suggestions of replacement?? I ASSUME the firing spring tension will hold it in place like a military

Thank god for a strong magnet. On the floor with a magnet on the end of a bar sweeping under the workbench. FOUND IT 5/64 dia 3/16 long.

Just so you know, you can't install the shroud with the safety in the on position. Wedge a penny between the CP and the shroud, flip the safety off, screw he assembly in, and then remove the penny.

I keep pennies on my bench for that; and just did one 2 minutes ago.
Anyway, I don't know where you got that pre 1902 firing pin. All the MK 10s I have seen have the internal safety lug. Maybe they made some......
Ram, send me the whole works and I will unf*ck it for you.

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Just so you know, you can't install the shroud with the safety in the on position. Wedge a penny between the CP and the shroud, flip the safety off, screw he assembly in, and then remove the penny.

Mike,
Am I just having an old man brain fart? Are the left side FN, Military and right side after market all the same? Or just the FN and after market because they only swing half way?

I know I've held the cocking piece back with a dime and love the MKX with the pin hole to hold it back.

I sure don't remember using a dime on the second FN but it has been 5 years and 5 major surgeries since I put it together. Heck didn't even remember the indent spring.

dpcd Thanks for the offer but then MKX assembly is in the MKX bolt that came in the rifle. Headspace is correct and the FN parts are going in a bag in the parts box. I found the spring to put the other FN back together and all is good.

Chalk it up to senioritis. Thanks for all your help right now just feeling a little .

I'll go back to the duplicator it is easier.