Updated info in post#99 Preferred Barrel 6mm Creedmoor help

[Justice1327]

6MM Creed—- Need some help with this barrel. This is a Preferred Barrel blanks barrel. I'm using short action Customs modular dies , Nexus press/Co-Ax, mandrel for a 2.5thou neck interference fit, Alpha virgin brass, CPS at 5thou crush, CCI450, H4350, V4 pwdr dispenser, 103gELDX, Defiance Classic in bedded McMillian , (I have put it in a chassis, and it shoots the same) weather: 75d, humidity85%, 2-5mph wind. Group was shot and then I used an air cooler to cool the barrel to where it is just warm to the touch. It is a .810 diameter barrel w/ a 7.5tw. SRS 3 port brake. Breathing was good and I had a good trigger press except for 2 or 3 shots. 12pwr SS scope. I've checked the scope screws, muzzle brake, action screws, and all our tight. Shooting off a rest. Any help to tightened up the groups is appreciated.

I am thinking about changing the bullet first. But the guy who has this Rifle really wanted to use the 103 ELDX
Also, I'm thinking about switching powders to superperformance or RL 17/19
100Rds
Slightly heavy bolt lift at 43.3

First pic with a COAL of 2.795
Bottom row is 41/41.5/42g
Added third pic with various bullets

 

[FireFlyFishing]

How many rounds down the tube…are these the first?

How far is your seating depth from Jam?

Perhaps a new powder. If that doesn't work, try the ELDMs?

Did you use a chronograph?

 

[Eric H]

7, 7.5 or 8 twist?

 

[K.E.C.]

40.5 looks promising.
What firing are you at with the brass,
Sorry if I missed that.
Are you seeing pressure at 43.3

 

[waspocrew]

How far from the lands? I'd try adjusting the seating depth. If there's no improvement, try a different powder.

 

[Eric H]

If you haven't so far, set the bullet at recommended COAL. Use base to ogive as a reference and work up .4 grains starting from 2 grains below maximum load. Take the best group and tinker with seating depth at .01 increments.

 

[1stpitch]

42g is your best group, and looks promising. Play around there some more. I shoot 42.1g in mine, and it shoots ¼", but I cut a slightly longer throat than is common.

 

[Justice1327]

How many rounds down the tube…are these the first?

How far is your seating depth from Jam?

Perhaps a new powder. If that doesn't work, try the ELDMs?

Did you use a chronograph?

~100rds
2.84 is 5th off jam
Velocity is posted on the second pic, but yes for all shots

 

[Justice1327]

How far from the lands? I'd try adjusting the seating depth. If there's no improvement, try a different powder.

First pic had seating at 2.795, second pic at 2.84

That's what I'm thinking too. I might try some Sierra tipped match Kings first.

 

[Justice1327]

42g is your best group, and looks promising. Play around there some more. I shoot 42.1g in mine, and it shoots ¼", but I cut a slightly longer throat than is common.

Thanks
when I seat the bullet to a 2.84 COAL only about half the length of the neck is making contact with the bearing surface of the bullet.

 

[Justice1327]

7, 7.5 or 8 twist?

7, 7.5 or 8 twist?

7.5tw

 

[Justice1327]

If you haven't so far, set the bullet at recommended COAL. Use base to ogive as a reference and work up .4 grains starting from 2 grains below maximum load. Take the best group and tinker with seating depth at .01 increments.

That is very close to the first attempt as seen on the first pic. Made one change and that was the seating depth, and tried to fine-tune the powder charge as seen in the second pic

 

[Justice1327]

40.5 looks promising.
What firing are you at with the brass,
Sorry if I missed that.
Are you seeing pressure at 43.3

Virgin brass
Slight heavy bolt lift
No ejector marks and primers are still rounded and almost 0 cratering

 

[Eric H]

That is very close to the first attempt as seen on the first pic. Made one change and that was the seating depth, and tried to fine-tune the powder charge as seen in the second pic

Appears you went closer to jamming the bullet. Have you pushed it further away.