Need help analyzing targets

[NW Hunter]

I am trying to redevelop a load for my Savage 6.5x284 after having Apache Gunsmithing clean up the chamber. Brass was hanging up due to a breech stamp being applied too close to the chamber mouth.
58.0 grains of Retumbo at .050" off the lands was shooting .247" at 100 yards before returning this Criterion barrel.

Reshooting 58.0 after getting barrel back did not repeat a good group.
58.2 and 58.3 groups both were 3" high and 58.4 was 2.6" high. All three of these loads shot .547" groups at 100 yards.


Which charge would you reshoot?

I have already shot loads at .025" and .075" off the lands and they were no go.

I'm thinking of moving lands adjustment in and out by .005" increments from .050".

Sorry about going sideways

 

[FearNoWind]

I'd work with the 58.5gr 2498fps load

 

[Greyfox]

Given the only change in the barrel was the chamber clean up I would look to the potential changes resulting from the chamber work that was done. If you have head space measurements from before and after the chamber work, I would take a look at this. I would try your best current or priot load using once fired, neck sized brass. I would assume the barrel was removed from the reciever for this work. It is very possible to see POI and accuracy changes when a barrel is removed/replaced from the reciever. I would also take a look at your bedding, on the assumption that the action was removed/replaced for the barrel work. Finally, I would check the neck dimension on your fired brass which should be .296", or about .004' larger then the neck diameter of your finished bullet.
Just some thoughts.

 

[NW Hunter]

Thanks for the tips guys. I value both your opinions.

Fear no wind, I thought it was strange that 58.4 gr had a velocity drop compared to the 58.3 load. 58.5 gr impacted the target at the same height as 58.3gr. Have you seen this up and down in different charges alot?

Greyfox, CBTO before sending barrel in was 2.501" with Berger HVLD 140s. Apache milled .004" off the breech to remove "6.5" stamp before cleaning up chamber. New CBTO is 2.497". I used this new figure to put the ogive at .050" off the lands
Maybe I should have left new loads at the original CBTO of 2.451"?