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Posted: 7/16/2015 5:44:11 PM EDT
I have a nice 300 Blackout with a 1:7 twist and decided to go supersonic only and figured maybe I should try a slower twist to see how the 110gr and 125gr bullets would do. I don't think the slow twist is at all popular but I have a barrel I can try with a 1:12 twist and wanted to know if anybody else had gone that route and how did it work for them? I made the mistake of asking over in the "build it yourself" forum and got replies about gas port location and the 1:12 was not the right twist rate for subs but no replies from anybody that actually might have tried supersonics in a slower than normal 1:12 twist rate for the 300 Blackout.

I do run supersonics in my existing 300 Blackout but was wondering if there was any benefit in using the slower twist rate for running supers only?
Link Posted: 7/16/2015 6:15:20 PM EDT
I just used Bryan Litz's Spin Stability calculator to see if this was a viable combo with a 12 twist.

Based on the data I input, with a 110gr VMAX, it appears to achieve spin stability from very low velocity to 2375fps mv.  Twist Rate Stability Calculator
Link Posted: 7/16/2015 7:31:37 PM EDT
[Last Edit: 7/16/2015 8:37:37 PM EDT by 22_boomer]
Yea, I've been through the twist calculators and all should be good but I was wondering if anybody actually tried a 1:12 for supers in the 300 blackout. I'm not sure there would be any benefit but I would like to hear from somebody that tried it.

Edit to add: I did some checking around and there doesn't seem to be any benefit to the slower twist for what I want to shoot. The faster twist allows the bullets to really open on impact. I guess I found the info I needed.
Link Posted: 7/17/2015 3:44:23 AM EDT
I went 300b simply for the versatility but tagged for other info on the round.
Link Posted: 7/17/2015 5:21:09 AM EDT
My first one is 1 in 10 and it works well with the lower weight supers.  I can even get it to work with heavy gr subs.  it loves my 247 cast subs.  but a lot of people have issue with subs and the 1 in 10 or slower twist

if you are going for a super only gun then you can do well with a 1 in 7, my model 7 shoots supers fine.  but if you want a slower twist then I would personally go no slower then 1 in 10
Link Posted: 7/17/2015 8:19:23 AM EDT
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Originally Posted By garyd:
My first one is 1 in 10 and it works well with the lower weight supers.  I can even get it to work with heavy gr subs.  it loves my 247 cast subs.  but a lot of people have issue with subs and the 1 in 10 or slower twist

if you are going for a super only gun then you can do well with a 1 in 7, my model 7 shoots supers fine.  but if you want a slower twist then I would personally go no slower then 1 in 10
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I'm like you in a way -- I have a whisper with 1:10 twist and it shoots just about everything I put in it up to 200gr Sierra Spitzer game king bullets. I shoot all kinds of stuff from my 1:7 twist 300 blackout and it shoots really nice but I have found I prefer the lighter bullets at supersonic speeds and from the info I found the 1:7 twist does not really over stabilize the bullets but the spin does make them really open up on impact. I'm going to pass on the 1:12 twist barrel.
Link Posted: 7/17/2015 9:29:04 AM EDT
If you reload and plan on only shooting supers, and also plan on chambering a slower twist barrel, it would be far more prudent to alter your plans and go with the 762x40wt or something similar. The 300blk leaves a lot of potential on the table in the supersonic arena, it's only advantage is factory fodder available at Walmart and other retail outlets.
Link Posted: 7/17/2015 10:33:18 AM EDT
[Last Edit: 7/17/2015 10:35:07 AM EDT by 762x40mm]

yep....I've done 10, 12, and 14 twists for the 300 and x40 in barrel lengths from ~ 10 to 22 inches for dedicated super-sonic....

most twist calculators are close, but I ended up building one in excel for the work I do....it's based off empirical data from hundreds of wildcat barrel tests..

simple answer: yes, the 12 and 14 twist barrels will work with light fodder...

we've run bullets so slow on twist that they look like a poorly thrown football pass, the bullet cuts a hole about four times diameter through paper without keyholing...think wobble wobble...

one of my favorites is a 16" 1:12 CZ 527 using factory Hornady 110 vmax suppressed, sounds like a 22 and makes holes like a 300 Winmag in lil West Texas venison...














Link Posted: 7/17/2015 4:51:37 PM EDT
[Last Edit: 7/17/2015 4:52:35 PM EDT by 22_boomer]
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Originally Posted By 762x40mm:

yep....I've done 10, 12, and 14 twists for the 300 and x40 in barrel lengths from ~ 10 to 22 inches for dedicated super-sonic....

most twist calculators are close, but I ended up building one in excel for the work I do....it's based off empirical data from hundreds of wildcat barrel tests..

simple answer: yes, the 12 and 14 twist barrels will work with light fodder...

we've run bullets so slow on twist that they look like a poorly thrown football pass, the bullet cuts a hole about four times diameter through paper without keyholing...think wobble wobble...

one of my favorites is a 16" 1:12 CZ 527 using factory Hornady 110 vmax suppressed, sounds like a 22 and makes holes like a 300 Winmag in lil West Texas venison...


http://www.ar15.com/media/viewFile.html?i=47605

http://www.ar15.com/media/viewFile.html?i=47606

I would guess by your ID that the rifle in the picture is in 7.62X40 -- am I right? Have you chony'd the velocity on the 110 v-max?








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Link Posted: 7/17/2015 8:11:14 PM EDT
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Originally Posted By 22_boomer:

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Originally Posted By 22_boomer:
Originally Posted By 762x40mm:

yep....I've done 10, 12, and 14 twists for the 300 and x40 in barrel lengths from ~ 10 to 22 inches for dedicated super-sonic....

most twist calculators are close, but I ended up building one in excel for the work I do....it's based off empirical data from hundreds of wildcat barrel tests..

simple answer: yes, the 12 and 14 twist barrels will work with light fodder...

we've run bullets so slow on twist that they look like a poorly thrown football pass, the bullet cuts a hole about four times diameter through paper without keyholing...think wobble wobble...

one of my favorites is a 16" 1:12 CZ 527 using factory Hornady 110 vmax suppressed, sounds like a 22 and makes holes like a 300 Winmag in lil West Texas venison...


http://www.ar15.com/media/viewFile.html?i=47605

http://www.ar15.com/media/viewFile.html?i=47606

I would guess by your ID that the rifle in the picture is in 7.62X40 -- am I right? Have you chony'd the velocity on the 110 v-max?












the rifle in the pic is a CZ527 chambered in 300 blk shooting factory Hornady 110 VMAX 300 whis/blk....the factory 110 loads clock around 2,400fps if I recall correctly...a similar rifle in x40 will push 110s around 2,700fps with hand loads...

Link Posted: 7/18/2015 9:24:14 AM EDT
[Last Edit: 7/18/2015 9:25:27 AM EDT by 22_boomer]
Thanks for the information. I have shot the Hornady 110gr 300 Blk and the Remington 125gr 300 Blk ammo and did my own 110gr and 125gr hand loads to compare them at the range. To my surprise the handloads and factory ammo all shot into the same hole. The round is easy to make cases for and load although I have thought about doing a 7.62X40.

At what range did you nail the deer? What brand is the suppressor? I had planned to put an AAC 762 SD suppressor on my 300 Blk but ran out of funds doing other projects -- can't seem to stay focused on one project.
Link Posted: 7/18/2015 9:52:02 AM EDT
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Originally Posted By 22_boomer:
Thanks for the information. I have shot the Hornady 110gr 300 Blk and the Remington 125gr 300 Blk ammo and did my own 110gr and 125gr hand loads to compare them at the range. To my surprise the handloads and factory ammo all shot into the same hole. The round is easy to make cases for and load although I have thought about doing a 7.62X40.

At what range did you nail the deer? What brand is the suppressor? I had planned to put an AAC 762 SD suppressor on my 300 Blk but ran out of funds doing other projects -- can't seem to stay focused on one project.
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that doe was taken from the 'cliff' blind at a buddies place in Texas....from that blind you're about a hundred feet higher and 110 yards from the feeder...

the rifle is set-upwith an SSK suppressor....

Link Posted: 9/3/2015 12:51:01 PM EDT
The original wildcat cartridge the .300 Whisper was based on has a 12 twist. It is called .300 Fireball.

The 1:12 twist is common in .30 caliber. It is the standard twist for .30-30 and .308, and both of those rounds can shoot 170-180 grain bullets accurately at subsonic velocities. .30 Carbine is 1:16" and can accurately shoot 130 grain bullets at subsonic velocity.
Link Posted: 9/3/2015 4:32:54 PM EDT
My .30 HRT 16" is a 1:12 and it does great with the 110 gr. TTSX and 110 gr. V-Max, but it is considerably faster than the .30BO.
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