91/30 suddenly inaccurate

olympia

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I have a sporterized 91/30 that i have fired at least 1000 rounds out of with no problem. It has a 4-12 scipe on it giving me 1" groups at 100 yards allnday everyday until the last 2 range sessions where the bullets are landing 8" apart. I changed my scope and rings and made sure the mount was tightened up. I made sure the tang screw and the screw under the mag was tight but it just wont shoot well anymore. I noticed the bolt is alot hard to work after i take a shot. I have fired mostly russian surplus and chinese surplus ammo in this thing with only about 30-40 sp rounds. What could it be?
 
I have a sporterized 91/30 that i have fired at least 1000 rounds out of with no problem. It has a 4-12 scipe on it giving me 1" groups at 100 yards allnday everyday until the last 2 range sessions where the bullets are landing 8" apart. I changed my scope and rings and made sure the mount was tightened up. I made sure the tang screw and the screw under the mag was tight but it just wont shoot well anymore. I noticed the bolt is alot hard to work after i take a shot. I have fired mostly russian surplus and chinese surplus ammo in this thing with only about 30-40 sp rounds. What could it be?

You said above you changed scope and rings.
Now English is not my first language, but it sounds like you did something to your original rig.
If yes putting it in the original configuration should solve your problems
 
You said above you changed scope and rings.
Now English is not my first language, but it sounds like you did something to your original rig.
If yes putting it in the original configuration should solve your problems

I put a new scope and rings on it the 1st time i noticed the gun was inaccurate, changing the scope and rings did nothing to improve the situation
 
Take off the scope and try grouping with irons at 50. if you still can get a decent group, you might have to explore the possibility of a worn chamber or shot out barrel. Take a look at the brass if you feel that the extraction has become a bit more difficult it might be a sign of a worn chamber. Or see if your bullets are tumbling and keyholing on your target. Mosins are tough but if you are using corrosive surplus, all bets are off the table.
 
Take off the scope and try grouping with irons at 50. if you still can get a decent group, you might have to explore the possibility of a worn chamber or shot out barrel. Take a look at the brass if you feel that the extraction has become a bit more difficult it might be a sign of a worn chamber. Or see if your bullets are tumbling and keyholing on your target. Mosins are tough but if you are using corrosive surplus, all bets are off the table.

x2 this is what I was thinking. Possibly ammo too?
 
Before giving up on it or getting carried away, you mentioned tightening the action screws. They may be over torqued and one of the reasons your bolt is difficult to work is that the rear screw may be rubbing against it, look at your bolt for new marks. A good glass bedding job won't hurt anything either and will keep everything in place.

You don't mention your cleaning regimen. I suspect it's quite good if you've shot as much corrosive ammo as you claim.

I had a similar thing happen with a No1 MkIII Lee Enfield. It was one of the most accurate milsurps I owned and regularly shot ammo it liked under 2in at 100yds. One day it just quit doing so and like yours started grouping into 6-8 inches. Yes, I had stripped the rifle down to its component parts for its yearly complete cleaning. When I put it back together I inadvertently over torqued the King Screw. I screwed up the ways on a 100 year old rifle. The barrel now had less upward pressure on it and some side pressure from the barrel channel. I had definitely changed the harmonics and stresses by getting to aggressive with tightening the King Screw. Sadly, finding a decent replacement stock was not an option. This rifle has a great history as well as great wood with lots of cartouches present. No way was this stock going to be relegated to the wood pile or go onto a different rifle. Because the wood was over a century old it was going to be difficult to find wood that could be matched and be dense enough to withstand the recoil it would be subject to. Luckily I found a damaged butt stock on a gun show table that was about the same age and sound. The original ways were chiseled out and replacement wood glued in and carved to shape as well as having copper shim plates added to the front of the way shoulders as is sometimes seen on No1 rifles. With a very little bit of tweaking the rifle shot as well as it ever did.

If there is nothing obvious other than the stressed bolt, there are two things you have to do after you pull the rifle from its stock. Check the bolt operation once it's out of the stock. If it's operating normally that isn't your problem but it is an indication of what the cause of your accuracy demise is. Check the bedding. You don't mention if your stock is a replacement or cut down military issue stock. IMHO, you have a bedding problem that may or may not be fixable with some glass bedding.
 
Check ammo quality at closer range with irons, Action screws, bedding, and front sight for movement. If all else fail cut back on beers.

Ammo is the same as before when it was shooting good. Russian surplus, chinese surplus...it all shot good. Cleaning regimen? Squirt some brake cleaner down barrel, run 5-6 patches thru or until they come out clean and some brake cleaner on the bolt. I use btake cleaner, caeb cleaner, hoppes, rusty duck...whatever is availible at the moment.
 
i may have figured it out but i have to go to the range to to confirm. Turns out i had 2 guns taken apart at the same time. I dropped my m44 into an archangel stock with detachable mag. When i was putting the 91/30 back together i accidentally picked up the m44 mag and installed it on my 91/30. Im thinking it fits differently enough that its disturbing the harmonics of the barrel. I guess only a range trip will confirm.
 
I don't think the magazine would be the issue. Maybe the archangel stock is not seating the receiver and barrel right? I know my only issue with the nagant was when my front sight came lose and one other time when I would over heat the barrel with the 10 round archangel mags, 10 rounds and your accuracy is gone...

I don't see how your shooting fine one day and not the next, and the bolt suddenly being stiff is strange. Lots of mosins have it but I never seen it develop over night.

Give 25 yards a try with irons, try throwing it back in the wood stock, maybe its not the gun at all and possibly scope/mount/stock. You never know, we had a vortex out that was wonky out of the box before 20 rounds and broke soon after 20. Even at 25 you should be able to see your grouping and get and idea, make sure you bench rest the gun cause we all know the mosins like holding a branch out.

If all else fails break it down and use it for parts. I had bad luck and have gone through 2 mosins, One I damaged badly over time from testing out my gunsmithing skills, the other bolt face was damaged after a erupted cartridge, its also damaged the chamber. Both times I sold them for parts.
 
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