AR15 in 6.8 spc

[7br]

Got to the range today. Loaded up rounds at 1gr of 4895 increments starting at 21 going to 25 grains. Shot one 5 shot group of each load at 50 yards.

wt width height total
21gr --- --- 2 1/4 in. Round group
22gr 0.75in 2.00in 2.25in
23gr 0.75in 2.50in 2.50in
24gr 1.00in 1.25 1.50in
25gr 1.50in 0.75 1.50n.

Think I may go up from here. Did have trouble feeding some rounds. I will check adjustment on dies and make sure I am full length sizing. Cases are coming out pretty dirty with some carbon about midway down on the shoulder.

I did start using an m-die and sizing the boolits to the last groove. Also seating them out longer. I am about out of Javelina lube. I have Thompson Blue angel pushing it out. I should be sizing a bunch of .45 acp soon, so I will see how the thompson holds up.

Thoughts or directions to go?

[Russel Nash]

what kinda velocities are you getting?

[7br]

I have not chronographed my cast loads. Just guestimating, I would say arount 1900 fps. With a 110 sierra, I am getting right at 2800 fps with close to max H322.

[morme@gte.net]

Are you guys aware of the group buy for the Lee 110gn plus 125gn duplex mold?

http://gunloads.com/castboolits/show....php?p=1229775

[Good Cheer]

The Lyman 280473 looks like a skim cut across the top of the blocks to put the gas check closer to the neck and a pin installed to make a little shorter ogive might be worth while.
How big of a flat could it have on the nose and still feed OK? Very much?

[morme@gte.net]

Just got back from the range. I shot all the bullets previously listed.

Quick conclusion
Lee C277-125R with 23 grains RL 10X was by far the best performer. Next was either the Lee C285-130R sized to 278 with the same load, or the RCBS 27-130-FN also with 23 grains RL10X.

The Lee 7mm Soup Can was the worst. I could only hit the 12" steel plate 75% of the time at 100 yards. I would say it had 12" or larger groups. Neither of the old Lyman bullets did well (with RL10X), either the 280473 or the 280468.

Here are pix of the targets I took with my cell. Note, my reference shots was a 3 shot group of factory SSA 100gn SP (Nosler white tip) bullets. The target shows my first 3 (cold bore) shots. Rings are 1/2 inch apart.

SSA Refererence


C277-125R 100 yds 23gns RL10X 1.05" center to center


Lyman 280473 100 yds 23gn RL10X


RCBS 27-130-FN 100 yds 23gn RL10X


RCBS 27-130-FN 50yds 21.5gn RL10X


C277-125R 50 yds 23gn RL10X


RCBS 27-130-FN 100 yds 23gn RL10X

[7br]

Can you give particulars on your firearm? Kinda interested in gas system length.

[morme@gte.net]

Standard carbine 16" barrel. SPCII throat. bullets seated to magazine length, which is .010 off lands in my gun. I used a stoney point case length gauge.