6.5 CM SIGHTING problems

[LBEdgin]

Has anyone had this happen to them?
Had my buddy Bergara sighted in with 130gr Accubond shooting .6" group using Hybrid100v and .8" using Varget. Was well pleased with these groups, but my buddy had picked up a box of Hornady 140gr HPBT he wanted to try. I worked up three different loads, in which he would shoot 3 rounds and I would shoot 3 of the three different loads. The results we got on all three test loads were promising with one getting to .8" to 1.1". But all three loads averaged 4" to the left of bullseye. I first thought he had bumped the scope. But when the 130gr were shot again the gun shot 1" high dead center just where it had before we tried the 140gr. Does anyone have any ideal of what may be causing this?

Thanks for any input!
David

 

[Darryle]

Maybe this is a possibility, the jacket is harder on the Hornady causing less drift?

Link:

What is Spin Drift?

 

[Rosebud]

Different bullet design, different speed. Leaving the barrel at new vibration node sends it to new impact point.

 

[LBEdgin]

Well that would explain why they grouped as good as they did, but I sure wasn't expecting that.

 

[hesse]

It is what can happen when you change bullet design or weight. I have a 264 win . That I shoot Hornady SST in in the 129 grain and the 140 grain the point of impact difference between the two is almost 3 inches horizontal and 2 inch's vertical

 

[LBEdgin]

One would think I would have had this to happen before, as I have been handloading 35+ years but have not. The up & down switching bullets weight I have but I expected it, but side to side I didn't see coming. Thanks for everyone's impute.
David

 

[Rosebud]

One would think I would have had this to happen before, as I have been handloading 35+ years but have not. The up & down switching bullets weight I have but I expected it, but side to side I didn't see coming. Thanks for everyone's impute.
David

One more lash on this dead horse. When you put a suppressor into a barrel it usually shoots low and left. Not always but most times.