The Russian Mosin Nagant Forum

Question on bore diameter


Hi all,


I just recently bought a PU sniper from SOG. I have some questions for you guys;


Rifle is a 1937 Tula round receiver, numbers match, the mount has been electro-penciled to match. Scope is a real PU, stock is decent and the bore looks very good and crisp. Took it out for the first time and the damn thumb screw to lock the scope mount drifted off and got lost. Was really pissed, but Century replaced it with another. Second time out, with a locked down thumb screw, i was able to hit on target 2" groups at 100 yrds using Czech surplus, but i was hitting at 4 o'clock. A guy at the range told me to check the tightness of the receiver screws, and sure enough, they were loose. Upon tightening them, I couldn't hit the side of a barn. Not to mention the sticky bolt syndrome.

I have been lurking now sucking up as much info to get to remedy these problems. Here are my solutions sofar

1. I took the bolt apart, cleaned the snot out of it, and polished the lugs and all point of contact. I also got a new bolt spring kit from C&R Surplus. I replaced the sear spring with a nos Finnish sear spring and also installed that littlr slack spring to tighten up the trigger. Then i took a .30 chambermaid brush mounted on a vinyl covered cable and used it with my drill to polish out the chamber. I used JB bore paste and Kroil to polish it and the whole bore out. I slugged the bore and the mic read .312.5 to .313. Is that good, bad or indifferent?

2. I have read about free floating the Mosin barrel and shimming the contact points on the reciever and the on the bottom where the trigger guard and magazine mount. I bought some brass shim stock to do this. Do you guys think that this will help prevent the tang screw from drifting loose and out? Have any of you done this and seen positive results?i.e., improved accuracy?

3. I have read about shimming the sear spring and how that can help the pull on the trigger, but upon reading the threads on this forum, i have decided not to do it. I read some of what you guys have stated that this can be dangerous. Have any of you actually done this? If you did, what were the results?

I want to commend you guys on what a nice forum you have maintained. In the short period i bought the sniper, i have learned a lot. Now to make you guys cringe....i have a numbers match Finn and a numbers match Tula still sitting in their boxes for the last 2 years. Never took them out, still cover in the cosmoline. Just couldnt get myself motivated to deal with that. However, since i have bought the sniper, i think its time for them to come out now.


Mike

I'm not sure i would of polished the bore but maybe it is ok. Make sure your chamber is clean of dried cosmo and if you have used laquerd primers they can cause sticky bolt. A good cleaning with boiling water will help with the dried cosmo. Check the extractor groove in the chamber for dried cosmo. The shimming can't hurt but you have to find a zero first and then experiment with the shims at different places to see if it closes up your group. Also you may have to try different ammo to see if your gun likes one in particular. If it was me....I would get a collection of different ammo for testing and find the happy spot with the one i have the most of. Then i would do testing of shims and ammo. Honestly a 2moa is not too bad if you ask me but you may get better. MAke sure all screws are tight and headspace is good and no more polishing

I apologize, i only polished the chamber with the drill chucked chamber maid brush. I did use a Dewey rod with patches and bronze brushes in the bore. I used Sweets 7.62 then scrubbed with the bore brush. I did use the Kroil and JB bore paste and the crud kept on coming out. Sprayed the bore down with brake cleaner and then mopped it with Hoppes.


Mike

I am sure you are fine. Just becareful polishing on the bolt. I use boiling water then clean while hot and then shoot and clean while hot then followed by boiling water again and clean while hot. After that it should be fairly good. The more you shoot the better the bore will come clean.

GUYS THERE ARE NO PU snipers before 1941 NONE. Any rifle can be turned and force matched to look right and font matched.Even the recv'rs I regret to tell you do not have a PU sniper, you may have a PEM sniper if it has the CH. The scope is worth more than the ruined rifle.
THE SCOPES will have round screws. they will have the year of manufacture in the first 2 numbers on the scope 43XXXXX a refurb indicated by [X] or [/]
What people may not realize is that the scopes can be turned down as well the mount may be ep'd or stamped. most have a readable Izhevsk triangle on the lower front. The knockoffs or newer ones are much smaller.
A PU is TULA 41 to 45 with a CH stamped on it. It may or may not have the scope number stamped.
Izhevsk 43-45 some later not much maybe a scope number on the side, lined out ground, or turned off. You can see the tool marks on the recv'r.
I am by NO MEANS an expert, but this is really basic Mosin stuff. Really it is. I am not trying to ruin your day, and I might be wrong. But I doubt it, don't ask the wife. Last time she was wrong and I was right was the day we got married

Thanks for the clean the bore tips. Been having trouble with one of my T53's getting 100% clean bore.JGC