Thread: Fixing Run-out

So tonight we tried some different things, it was a bit beyond my control (gunshop being obliging and tying things). Changed projectile to Sierra 100 gn TGK's and powder to Stabil 6.5. All loads done by gunshop, some on my dies, some on theirs, brass the same, some of mine, some of theirs (but not mixed)

Tried a load that shoots lights out in an identically chambered rifle. Shot one 14mm 3 shot group but nothing else duplicated it, the other group of identical charge weight being 40mm. The other 3 groups of a variety of charge weights being 30 -40 mm.

The fact that the results are so random leads me to thinking maybe its something mechanical and I'm wondering if it could be ignition (the rifle is in a chassis that another action will shoot bugholes from, and I'm using a torque screwdriver). When I disassembled the bolt some time ago I did notice the mainspring was " bound" and didn't look happy - thoughts on this sort of problem being a cause of accuracy issues??