I can’t figure this out

[Korhil78]

Rifle: 6.5 Sherman
Bullet: 140 Gr Berger VLD
Powder: Retumbo
Load: 64 Gr seated at 2.870 (Hornady OAL Gauge)
Barrel wasn't cleaned.
Target distance: 300 yards

First shot is the one at the top of the target (I was aiming for the center bullseye).

Second and third shot are together right beneath that.

Shots 4-10 are in that grouping that measures 1.5" ctc. At 300 yards, I will take that grouping all day with 7 shots but I can't have my first three shots hitting that far off in a hunting situation! I can't figure out what caused it.

It was suggested that since I started shooting in low light that my point of aim was changing as it got brighter. I'm stumped.

 

[Korhil78]

Cases sorted by weight, necks checked with a concentricity gauge, annealed, resized with .002 neck tension.

 

[coop2564]

Something temp sensitive? How long between shots? Did you change how you were holding gun any between first few and last few (like go from bag to bipod or change bags?)

 

[Korhil78]

5 minutes between shots. I didn't change anything. Shooting off of a bipod with spiked bottoms and a rear bag.

What's even weirder is that the velocities were within 8 fps of the others in that bottom grouping.

 

[can1010]

I get that with changes in the way I preload my bipod

 

[Korhil78]

Well I tell you what, this will be the time that I'm glad it's me if it was. Just really weird how it walked down.

 

[Korhil78]

Oh and that bottom round was my last round fired and it came out of the barrel at 3156 fps. I had two rounds that were way easier to seat than the others and it showed with velocity differences in them. I culled both of those cases into the trash.

All the other rounds came out from 3192-3209 fps.

 

[can1010]

not to weird as you shoot you made small adjustments to get comfortable. try taking a shot ,get up walk around in circle and then get back on gun. I was really amazed how much it changed.

 

[Korhil78]

I will try it out again and see what it does. Seems to be a good load though If it turns out those three were me.

 

[coop2564]

5 minutes between shots. I didn't change anything. Shooting off of a bipod with spiked bottoms and a rear bag.

What's even weirder is that the velocities were within 8 fps of the others in that bottom grouping.

Yeah this is going to be hard to figure out. I would take a factory load and see if it did same tendencies, if not its something in loading. Maybe try different bullet or powder combo. But your right that grouping wont hunt at long range. Did it look good at 100yds?

 

[Korhil78]

Haven't shot it at 100. I will try it out again and if it does it again, I will know for sure something is up.

 

[coop2564]

Have you shot this load before without bipod and it did ok?

 

[Korhil78]

I always shoot off of a bipod and rear bag because that's the way I hunt LR. It shot a .8" 3 shot group at 300 yards last week. I haven't done a lot of extensive testing with it yet as I am working up a load for it.

 

[WeiserBucks]

Clean bore to start ?