Mosin-Nagant inconsistency... floating issue?

[Stavrogin]

Was out at the range again tonight and did some shooting with my Mosin-Nagant M91/30, and had some troubles. A couple of weeks ago I had this rifle out, and was able to produce a couple of 4-5" groups at 100M with the irons, well on target, after drifting the front sight post to the right (it had been shooting right).

Tonight, the rifle initially was shooting about 6" left! So I drifted the sight back to the left, aligning the sight with the original factory mark again. Got it to shoot on target for 10 rounds or so, then switched back to the .22 for a while to let the barrel cool.

Picked up the MN again, and suddenly, it's shooting 6" right again. For a few shots. Then comes closer to centre.

Is this likely a form/sighting/flinching thing (ie, me)? Or is this possibly an issue with the rifle itself? The barrel is floated between the end cap and the action, but there IS contact between the end of the forestock and the barrel, but only at that one point. Could changes in temperature/humidity in the course of an evening do this?

Not sure whether to blame myself or the rifle.

 

[Shadow 7D]

MAKE SURE YOUR SCREWS AREN'T LOOSE
that is really the number one, a loose receiver screw will do more to mess up your zero, than many other causes.
otherwise how is the bore, some, after 90+ years of service can be expected to pattern like a shotgun, that's life, and even barrels wear out.

Also a LONG thin barrel like the MN, will definitely react to the temp, you should shoot a 3 shot group to 'warm' the barrel, the start working on your zero

 

[Gunnerboy]

I got an ol mosin that shoots 4in groups when cool, but when that barrel heats up i get minute of barn.

 

[Der Stro]

I got an ol mosin that shoots 4in groups when cool, but when that barrel heats up i get minute of barn.

Happens to me as well. First three shots are within ~5moa but after that it just starts opening up to the point I'm not even on the target anymore.

 

[dprice3844444]

try some shims under the muzzle or bed the action

 

[nathan]

Wrap some packing tape just enough to snug fit the receiver lugs and tighten the screws front and rear. Tight but not too tight as to damage the threads. Bring with you a screw driver at the range to use once it loosens after several shots. Heat do make it loosen its tightness.

 

[caribou]

Tighten the action screws as instructed above, then tell us what happens.
It sounds like the action is moving, as heating will progressivly move the impact point, not just shift suddenly and stay there awhile.


look at your stock and look for an obvious warp pressing against the barrel. Shiming will adjust you on the vertical plane, if thats the way the wood warps, or has an area of contact, if the wood is pressing from the side, reliving that wood is the usual fix.

 

[HEAVY METAL 1]

Try this:http://http://www.surplusrifleforum.com/viewforum.php?f=186

I did several of these things and it helped considerably. Some of it could be a little dangerous if not applied prudently. Fiddling with these guns is a blast.

 

[Strykervet]

FAL trigger

sorry, wrong thread!

 

[browneu]

The link doesn't work.

Sent from my LG-P999 using Tapatalk

 

[vellocet]

The boxotruth site has a section about shimming the barrel with cork from a wine bottle. The guy says it works.