M91/30 Sticky Bolt

Tatsumi67 · October 29, 2008, 09:26 PM

Mosin of mine starts to lock up after firing, usually after 40 to 60 rounds. I tried some cheap silver bear, and then some B&H brass cased to see if it was an ammo problem.

Got the same problem, but less frequently.

I think it has to do with cold rounds going into a hot gun.

Any remedies?

the rifleer · October 29, 2008, 09:48 PM

this is pretty common with mosin nagants. its commonly referred to as sticky bolt syndrome. it it has ever had lacquer coated rounds through it or if it has a little bit of cosmoline in it then i can cause it to lock up.

from what i understand the best thing to do it just give the chamber a good cleaning and get any junk in there out.

Czech ammo is what causes it alot of times.

jhenry · October 29, 2008, 09:48 PM

This is a classic and common issue with the Mosin. The common wisdom is that over the years, laquer, cosmoline, and other gunk has been deposited on the chamber walls under heat and pressure creating a glaze that when heated gets a bit glue like and causes sticky bolt. It is worse with some of the laquer coated ammo, in particular the czech silver tipped surplus stuff. Try this first.

Dismount the barreled action from the stock. Take a 20 gauge brass brush in a section of cleaning rod and chuck it in a drill. Get it sloppy wet with laquer thinner or mineral spirits and run it in and out of the chamber. You will be amazed at the junk that comes out. I use a glass jar with the fluid in it and keep dipping the brush between uses. Last time I had junk precipitating out of the laquer thinner and settling on the bottom. This will likely cure the issue with little expense and no trip to a gunsmith who will likely do the same thing anyway. After you are done give it a normal claen and lube because you will have stripped all the oil out and rust could show up.

Also check the mating surfaces for excessive tool marks which could bind and take a look at the extractor. I have a M38 Mosin which bound up terribly and the sole cause turned out to be a poorly finished extractor which was catching on the rim. A few minutes work with a needle file, some fine emery and a felt bob on the dremel cured it.

Good luck and good shooting.

snolden · October 29, 2008, 11:48 PM

Yeah, I use whatever big heavy object I can to smack the bolt open sometimes.

They work and the straight bolt handle doesn't give a whole lot of leverage.

I have two MN's and they sit in the safe except about twice a year when I run about 20 rounds thru each.

October 29, 2008, 09:26 PM	#1
Tatsumi67 Senior Member Join Date: December 30, 2007 Posts: 575	M91/30 Sticky Bolt Mosin of mine starts to lock up after firing, usually after 40 to 60 rounds. I tried some cheap silver bear, and then some B&H brass cased to see if it was an ammo problem. Got the same problem, but less frequently. I think it has to do with cold rounds going into a hot gun. Any remedies? __________________ "Do what you can, what you want, what you must,feel the hunger inside, just don't lose your trust" - KMFDM, Trust. NRA Member,Minnesota State Safety Certified, Eagle Scout Currently schemeing on an AR-15 build.

October 29, 2008, 09:48 PM	#3
jhenry Senior Member Join Date: May 27, 2006 Location: Ozarks Posts: 1,840	This is a classic and common issue with the Mosin. The common wisdom is that over the years, laquer, cosmoline, and other gunk has been deposited on the chamber walls under heat and pressure creating a glaze that when heated gets a bit glue like and causes sticky bolt. It is worse with some of the laquer coated ammo, in particular the czech silver tipped surplus stuff. Try this first. Dismount the barreled action from the stock. Take a 20 gauge brass brush in a section of cleaning rod and chuck it in a drill. Get it sloppy wet with laquer thinner or mineral spirits and run it in and out of the chamber. You will be amazed at the junk that comes out. I use a glass jar with the fluid in it and keep dipping the brush between uses. Last time I had junk precipitating out of the laquer thinner and settling on the bottom. This will likely cure the issue with little expense and no trip to a gunsmith who will likely do the same thing anyway. After you are done give it a normal claen and lube because you will have stripped all the oil out and rust could show up. Also check the mating surfaces for excessive tool marks which could bind and take a look at the extractor. I have a M38 Mosin which bound up terribly and the sole cause turned out to be a poorly finished extractor which was catching on the rim. A few minutes work with a needle file, some fine emery and a felt bob on the dremel cured it. Good luck and good shooting. __________________ "A Liberal is someone who doesn't care what you do, as long as it's mandatory". - Charles Krauthammer

October 29, 2008, 09:48 PM	#2
the rifleer Senior Member Join Date: March 5, 2008 Location: Sunny California Posts: 1,281	this is pretty common with mosin nagants. its commonly referred to as sticky bolt syndrome. it it has ever had lacquer coated rounds through it or if it has a little bit of cosmoline in it then i can cause it to lock up. from what i understand the best thing to do it just give the chamber a good cleaning and get any junk in there out. Czech ammo is what causes it alot of times.

October 29, 2008, 11:48 PM	#4
snolden Senior Member Join Date: January 25, 2006 Location: N. E. AZ Posts: 387	Yeah, I use whatever big heavy object I can to smack the bolt open sometimes. They work and the straight bolt handle doesn't give a whole lot of leverage. I have two MN's and they sit in the safe except about twice a year when I run about 20 rounds thru each.