So I’ll try to explain as short as possible, buddy just bought a Christensen Mesa 338. He shot a few groups not so hot but breaking in the rifle as Christensen states. I go there today and he says shoot it, so I did. Peterson brass, rel 33, Berger 300 otm, misses 100 yd target completely to the right twice. Dial it over and can’t tell where it’s going. Loaded some more, here’s where it gets weird. Bore sighted as I do with every gun every time with no issues. Look through bore and align bullseye with scope. Usually always within a few inches of center and never off paper, until now, at 50 yds. Over 12 inches left. Now to center it we had to max out windage in the scope and found that the 40 min NF rail was too much for the scope and didn’t allow for enough horizontal travel. Tried another scope to be sure it wasn’t just the scope. Replaced with 20 min rail and was able to move over enough to sight in. Same thing bore sight looked good, shot way left. We then sighted in at 100 and shot 3 shot group, not great but consistent. Decided to load a few Barnes lrxs 265, same powder, case, primer, brass, poi shifts over 10 inches right at 100 yds. Dumbfounded by this we fired another Berger to be sure scope didn’t shift and it had not, that bulletin fired back in the group of bergers. Any ideas?
Grizz, David has the right idea to track down your problem. but if that was so the POI versus POA would not be shifting so wildly.
here is my suggestion.
take the MOA offset bases off, put on a standard 0MOA base on-remount the scope and zero
take various ammunition;
shoot at 50 yards on a 2' target.
see where the various ammo shoots.
if there is no consistency then I would start suspecting the barrel.
I just had a $3,000.00 precision AR come in with a similar problem. the barrel was a reject. it's possible to get a trashy barrel from anyone every now and then.