I have a super nice krieghoff 12 gauge over 7-65r. Gun was built in mid 80’s and has a zeiss 2,5-10-48 scope with claw mounts on it.

I am currently using 160 Norma tip strike factory ammo in the gun.

I am having 2 issues:

I am having a hard time keeping the gun sighted in. I don’t beat the gun up and it always rides in a padded case. I never take the scope off the gun.

Secondly, the 2nd rifle shot is 3-4 inches higher than the 1st and the 3rd is often off the target.

I thought this was normal until I shot with my friend yesterday who has a blauser combination gun. Using the same ammo, his 1st 2 shots were touching at 100 yards.

The barrel size and rib on the 2 guns look very close to the same size.

Any ideas would be appreciated. Could it be the forearm?

We were shooting off the same rest.