6.8mm SPC,Velocity comparison from 16 to 24" barrel

[Float Pilot]

I experimented with a 16 inch Stag factory barrel for a few years and just swapped it over to a 24 inch Black Hole Weaponry barrel.
These are the averages from 3 five shot groups of each type of hand load. These hand-loads were previously the favorites of the 16 inch barel and most were max in that barrel.
One thing I noticed with the new barrel, which has poly rifling, is that the pressure signs have backed off....


6.8mm SPC 16 to 24 inch barrel conversion velocity and accuracy test.
16 inch barrel, Stag factory 1 in 10 twist SPC-II chamber
24 inch barrel, Black Hole Weaponry, 1 in 11 twist, SPEC II. Poly rifled
Fired at @ 50 degrees F. Alt 350 feet.


90 grain Sierra JHP
28.8 grains H-4198
SSA Brass, CCI-BR-4 primer
COL- 2.200 inch, Lee Crimp
16 inch = 2,908 fps and 0.40 inch group
24 inch = 3,110 fps and 0.75 inch group


100 grain Bulk mystery SP.
29.7 grains H-Benchmark
SSA Brass, Fed 205 primer
COL=2.255 inch, Lee Crimp
16 inch = 2,650 fps … Large group
24 inch = 2,750 fps--- 0.50 inch group, no flyers.

100 grain Remington SP
31.5 grains AA-2230
SSA brass, CCI-400
COL-2.225”, Lee Crimp
16 inch = 2,580 fps Group over 2 inches
24 inch = 2,765 fps… 0.75 inch group

110 grain Nosler Accubond
29.0 grains H-322
SSA Brass, CCI-BR-4
COL-2.265” Lee Crimp
16 inch = 2,554 fps and 1.0 inch group
24 inch = 2,730 fps and one ragged hole at 100 yards.

110 grain Nosler Accubond
25.8 grains AA-1680
SSA Brass, BR-4 primer
COL-2.250”, Lee Crimp
16 inch = 2,500 fps and 1.5 in group
24 inch = 2,770 fps and 0.50 inch group average






110 grain Sierra Pro-Hunter
25.8 grains AA-1680
SSA Brass, BR-4 primer
COL-2.250”, Lee Crimp
16 inch = 2,470 fps and 2.5 in group
24 inch = 2,608 fps and 1.0 inch group average

110 grain Sierra Pro-Hunter SP
30.8 grains AA-2230
SSA Brass, CCI-400
COL 2,255”, Lee Crimp
16 inch = 2,550 fps,,1.0 inch group
24 inch = 2,730 fps ..0.75 inch group


110 grain Hornady JHP.
30.8 grains, AA-2230
SSA brass, CCI-400
COL=2.255, Lee crimp.
16 inch = 2,530 fps….. 2.5 inch group
24 inch = 2,760 fps----1.1 inch group

110 grain Barnes Triple Shock
30.5 grains AA-2230
SSA Brass, CCI-400 primer,
COL-2.237, Lee Crimp
16 inch = 2,550 fps 1.5 inch group
24 inch = 2,820 fps 0.80 inch group

110 grain Hornady Factory Ammo.
110 grain BTHP
16 inch = 2,455 fps
24 inch = 2,699 fps 1.5 inch group
110 grain Ballistic tip type load
16 inch = 2,506 fps
24 inch = 2,790 fps 1.0 inch group

130 grain Sierra S.P flat base
27.0 grains H-Benchmark
SSA brass, Rem 7.5 primer
COL= 2.55 inch, Lee crimp
16 inch = 2,220 fps…1.0 inch group
24 inch = 2,480 fps and 1.0 inch group
No pressure signs.

 

[shooter_from_show-me]

My load data for 6.8SPC

I have a 16" CMMG 1:10" twist w/ SPCII chamber.

Bullet 110gr Seirra PH's
Powder 29gr of H322
Seat @ 2.305" (PRI mags) Light Crimp w/ Lee FCD
Primer CCI 400's
Brass SSA

I can get MOA with this load @ 100 yards using a Aimpoint PRO optic. Don't know the velocity due to lacking a chrony.

 

[68wj]

Looking good.

 

[Float Pilot]

Now I just have to find some AA-2200 powder.... Looks like I may have to drive up to Anchorage for that... A NINE hour round trip this time of year.

Plus I need to find some 120 Grain SST bullets to see how they do....

I now have a little more pressure I can use without blowing the cases.