Point of impact change

[300 RUM]

This morning at the range I was shooting next to a friend , we both loaded up our ammo the other night for a match today, We did not go to the match because of work but anyway. The wind was at 15mph 1/2 value, I was able to hold a 1 to 1.5 moa at 200 yards give or take. He was having some issues with ammo I believe, this is what the question is about. He would shoot 3/4 moa or better for 2-4 rounds and then get a elevation change of about 1-2 moa and then group again at 3/4 moa or better. There were some windage flyers grouping also, but were more concerned with the elevation change

So the question is: Does he have a powder charge issue or it is possible the scope is jumping around?

 

[markr]

Tension on action screws? Bedding? Scope?

 

[jbpmidas]

I have a rifle that does something similar. I got better results after testing with different torque values on the action screws. Mine has an aluminum bedding block. I found some type of glue or adhesive on the block, so that I cleaned that off as well. Mine is a Savage. I have gotten several 5 shot groups in the .6's at 200 yards with that rifle. Some times I will get 3 under 1/4" at 200, but it always sems to open up to between .6 and .7. I think that is probably the limit of my abilities, though.

 

[300 RUM]

Oh I left out we both have AR-10's in 308