One for the Mosina Experts

[WelshShooter]

Looks like I have an extraction issue with my Finnish Mosina, M24. On my first outing after 15 rounds I could not extract the case after firing, the bolt would lift with normal effort and would move rearward without the case. The only way to remove the case was to drop a cleaning rod down the bore and give it a gentle tap to knock the case out. After chatting with some of the other shooters it sounded likely that there was some residual cosmoline left in the chamber which was melting after a string of shots and then solidifying on the chamber wall when I went to change my target. There was no problem with loading rounds from the magazine and the bolt closed with no additional force. Firing was normal, just that when I lifted the bolt and pulled it back the case did not come out. Closing the bolt again would not allow the extractor to pick up the case. In terms of loading the round and firing, nothing seemed out of the ordinary.

So I took it home, held it muzzle down and poured boiling hot water down the chamber and through the bore. I plugged the muzzle and let the hot water sit fir 5 minutes, then flushed it out and topped it up with more boiling water. I repeated this for around 20 minutes and then proceeded to dry everything out.

On my next outing, I didn't have an issues until around 45 rounds in. Perhaps I didn't remove all the cosmoline?

Tonight, I decided to try out some empty cases. I had some unfired cases and some fired cases which I had not yet resized. I fed 5 unfired, factory Lapua brass into the chamber by hand one at a time and then pushed the bolt forward and locked into place. When I opened the bolt the case came out no problem at all, as expected. It was only when I tried 5 fired cases did all of them get stuck in the chamber. Lifting the bolt and pulling rearward left the cases in the chamber. I inspected the cases and other than one set being fired and the other unfired there was no noticeable difference. The case length is 53mm (standard Lapua length) whereas the rifle has been proofed using 7,62x54mmR. The fired cases did not measured greater than 54mm so I do not think it could be a case length issue keeping them in.

I'm currently waiting for a bronze chamber brush to arrive so that I can give it a good scrub in case it's residual cosmoline. I've looked at the extractor and nothing looks out of the ordinary. Looking for advice from other Mosina enthusiasts, perhaps there's an easy fix to this? I was hoping to take it up to Sennybridge this weekend but it's doubtful, no point in taking the rifle up if it's just going to stick cases after each firing.

[hitchphil]

Get a chamber cleaning stick from Saddler..... put a 4x2 patch on it & moisten with some nail varnish remover (solvent acetone based or lawnmower petrol?) on it. sit it in there for a while then push & twist - if any brown black comes out on the 4x2 patch then you still have 'gunk' in there, repeat until none, or if it persists it might not be cosmoline?

if it wont come out or stop, go to a smith & ask them to ream clean the chamber as a build up of resin even brass on the throat can cause things to stick. Barnaul steel green cases with resin on the surface can do this - solvent hardly touches it. It becomes like a glass coating on the chamber walls & bolts stop closing, things get stuck.

[snayperskaya]

Sounds like a combination of Cosmoline (or muck/laquer etc) in the chamber and possibly a weak/bent extractor...had the same problem on my '39 and fitted a new extractor and that sorted it.Note that if you flush with boiling water it can cause flash rusting.Best thing I have found for softening Cosmoline is good old WD-40.....just let it soak and reapply as and when until the Cosmoline softens.

In the pic below the good extractor is on the left, the bad one on the right.The right-hand one would not grip the rim of the case sufficiently to extract the case........

[andrew375]

Strip the bolt, in particular remove the extractor and clean out what is underneath. You will probably find there is solidified grease or preservative in there stopping the extractor from seating back down after snapping over the case rim. This is why the first few cases come out ok as the extractor has had time to move to where it is supposed to be but then has been pushed back out.

[WelshShooter]

The extractor looked pretty clean from debris etc, but I did not remove it from the bolt head during my detailed strip because the general consensus online was that the extractor can easily be damaged or broken during removal or replacement so I was a bit hesitant at doing this unless absolutely necessary.

In terms of spares, does anyone have a source for spare extractors? My google-fu didn't turn up with anything in Europe.

I'll have to check to see if it's slightly bent or not, I won't be able to take a look until Saturday. I think I'll give the WD40 trick first, didn't think of this as I try to keep that stuff far away from firearms. If the fired cases are still staying in the chamber then I'll head down the extractor route. It could actually be a combination of both. If the cosmoline is situated at the case shoulder then unfired cases would slip out quite easily whereas fired cases would contact the chamber and stick in. If the extractor is dirty or weak then naturally it won't slip over the rim or will not hold onto the rim with enough pressure.

Thanks for the tips guys, I'll give them a try over the weekend!

[snayperskaya]

Rich, check out a seller on Ebay called "want4what", his name is Jarmo and is in Finland and he can source pretty much anything Mosin-related.......he also had a considerable supply of reasonably priced Soviet 1pn34 night vision scopes and complete spares kits for them at one time!.

http://www.ebay.co.uk/itm/All-Mosin-Nag ... SwnF9Y8IEV

[andrew375]

The extractor looked pretty clean from debris etc, but I did not remove it from the bolt head during my detailed strip because the general consensus online was that the extractor can easily be damaged or broken during removal or replacement so I was a bit hesitant at doing this unless absolutely necessary.

Just drop the bolt head into a jar of white spirits for a few days, that should ease things up. If you go to the library section of this site you will find a post by me with a link to Bolt Action Rifles by DeHaas which will tell you all you need to know about disassembling your Mosin.

[snayperskaya]

Mosin exploded views and disassembly......

http://7.62x54r.net/MosinID/MosinDisassembly.htm

[WelshShooter]

Thanks for the links guys. Today I removed the extractor from the bolt head which wasn't as difficult as it was made out to be, a dab of oil, drift punch and peen hammer made for an easy job (aside from needing an extra hand to keep the bolt head steady). It revealed a big build up of cosmoline, jackpot! I whipped out the WD 40 and the cosmoline slid off, so thank you for the tip Rich!

I noticed, however, that the extractor appeared to be bent slightly. I tried the unfired and fired cases again and lo and behold, the fired cases did not extract whereas the unfired ones did. I'll have to order a spare extractor ad get that sorted to see if that's a problem, the other cleaning supplies are taking their sweet time to arrive so at least I can try another avenue in the meantime.

Sorry Mosina, you do not get to breath the air of Sennybridge tomorrow

[snayperskaya]

Repeat after me........this is Cosmoline!