New BHW 24' barrel velocity comparison test

[floatpilot]

As some of you know I replaced my old 16 inch Stag barrel with a 24 inch Black Hole Weaponry barrel. Plus a new MI SS hand guard, low profile gas block and so on

I fired her today with 200 rounds of ammo that I had already tested in the 16 inch barrel. One thing I noticed is that the high pressure signs I used to have have disappeared, so there is room for improvement.

Here are today's test, firing three groups of 5 shots each for an average. Since the barrel is new, I had to semi clean the bore every few shots.



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.
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.

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[Swag]

Great info, thanks for posting it up.

[dr69er]

Looks Good, boy what a difference in velocity between the
16" bbl. and the 24" BHW bbl.

Good Luck with It.

[GLSHOOTER]

Very nice batch of info. So day in day out it looks like about 25 FPS change per 1" of barrel length on most powders. That seems to be in the ballpark estimates of most sources that I I have seen.

The actual PROOF is nice to have in your tool box.

Thanks,

Greg

[floatpilot]

I also noticed that I was obtaining 80 fps more velocity at the end of the afternoon, with some loads.
It was not because of a hot barrel since I was letting it cool for long periods of time. (wife had yard chores waiting at home so this was a 6 hour range session)

I think it was because the barrel pours were being filled up and the barrel was becoming smoother in the bore. I was using patches with FP-10 every 3 to 5 rounds.

Now I need to play around with some new loads to see what this gal can really do.

I used a 15 inch long Midwest Ind. SS type hand-guard and a VLTOR low profile gas block. The extra length hand-guard makes the 24 inch barrel not look so darn long. I coated the barrel and gas block in NAPPA ceramic high heat engine block paint. I used cast iron gray and baked it on with a heat gun.

Attachments:

[GLSHOOTER]

Some rifles will shoot faster after a bit of use. I've never worked with a poly barrel though I have shot a few over the years. My 20 LBC will be my first use of one full time.

I like how that tube looks.

Greg

[floatpilot]

I need to try some AA-2200 powder. If and when I can find some.
I may have to drive up to Anchorage for that. A NINE hour round trip this time of year.
Plus I am looking for some 120 grain SST bullets. They might hit a happy medium between velocity and weight.

I wonder how poly rifling does with moly coated bullets?

By the way, I am super happy that I bought this Black Hole barrel in a standard weight profile.

The rifle now balances about 1/4 inch ahead of the magazine well. With a 28 round mag, the scope, the steel Warne mounts and cleaning gear in the butt-trap, it weighs 8.99 pounds. It also swings and points fairly well.
I like the standard A2 butt-stock since it fits me perfectly. I may have to change the scope to something with more power. And maybe lower mounts. Right now it is a straight 6 power and the heavy duplex cross hairs cover small targets.
I used to be a 150 yard carbine. Now it is a 400 yard rifle.