Need some help troubleshooting horizontal grouping.

[VarmintBob]

It's pretty obvious from that target I posted that the muzzle movement is at the same spot in its vibration cycle when each of those bullets exited the muzzle. That muzzle position corresponds to the same time in milliseconds after ignition for each of the identical loads shot.

 

[Sealesniper]

I bed them all!

I sure tried to before I got married...Oh wait, you mean the actions. Sorry, my bad.

 

[OG10]

https://www.rifleshootermag.com/editorial/5-shot-group-shapes/454958 might be of help to read groups.

 

[OG10]

https://www.rifleshootermag.com/editorial/5-shot-group-shapes/454958 might be of help to read groups.

 

[BillNye]

Cartridge, powder, bullet, cartridge OAL, bbl length, fired, unresized case capacity in gr of water (weigh empty case fill with water weigh again, get difference) I normally do at least 3. Some velocity with the above specs and the powder weight used for that velocity. With all that I can get a time in msec of when the bullet exits to determine how close it is to a quiet muzzle time. The target below is 5 shots from my skinny bbl 300 WM at 100 yds. It is an OBT load.

300 PRC, 78.9gr H1000, 199 Hammer Hunter, 3.620", 28", 94.3gr, 3070 fps

 

[VarmintBob]

I don't have 300 PRC in QuickLoad but it looks like Node 5.5 will be around 3015 fps. The load you are shooting is a little over 63K psi.

 

[doverpack12]

Sometimes, the bullet powder combo just don't work for whatever reason even if they do for others or did in another rifle.
If you are fighting vertical or horizontal just best to switch a component of the load