I bought my second Mosin Nagant.  This thing shoots terribly.  8" groups at 50 yards.   The headspace is good, the rifling looks clean and crisp with an LED on the other end of the barrel.  The barrel has been crowned and that looks to be in good condition.

 

I was frustrated and decided to just see how much penetration the gun has and caught a bullet in a pressure treated 6x6 block.  (It had passed through 3 other 6x6 blocks first).

 

The bullet I dug out had a scratch next to one of the rifling marks.  So I shot a few more times and found the same mark on the bullet in the same place.  It appears that there is damage in the barrel that's causing this scratch but I can't see it with the naked eye.  I'm wondering if whatever is causing this scratch might be the cause of the inaccuracy.  Maybe not but I can't find anything else that's causing such terrible groups.

 

The whole gun cost me $120 so I'm not going to put much money into a repair - if it's even possible.

 

Anybody have a guess what's really happening here and is there anything I can do about it?

 

Could the bore not be the right size. Maybe slug the barrel and measure the slug it might have a bigger bore than 7.62 

Bend in barrel.

I think Mikey is likely on point here. The bullet might be tumbling as it exits the barrel due to excessive wear which will make it bounce as it travels through the barrel.