
Originally Posted by
Patrick Chadwick
As you can shoot well enough with a different Mosin, we can assume that you are not the problem. And if the rifle is OK at the front end, the trouble could be in the back end. The rifle may be badly worn in the throat, in which case you may need to go to hand-loaded ammo, as most factory ammo uses boat-tails.
Find out the maximum possible cartridge length - the method has been described several times in these forums, so search it out. If the max. length, i.e. the point where the bullet is just about touching the lands, is so far out that the bullet is completely free of the neck of the cartridge case, then the rifle will never shoot well with that bullet. Basically, the bullet has a substantial free flight in the worn throat, hits the transition cone at an angle, is engraved crookedly, and comes out of the muzzle with a skew that means the POI is all over the place! Hence the extraordinarily large group, which nevertheless has the centre in th emiddle of the target.
For a very worn throat, about the only pracatical answer is to use a flat-based bullet with the largest diameter that can be safely used in the chamber and the longest possible cylindrical section. The best choice is the Hornady #3130 flat-base round-nose 174gn bullet with a diameter of 0.312". They seem to be rare these days, but I think there is one from Speer that is similar.