1:10 twist with 300 Blackout?

Moderators: gds, bakerjw, renegade

Fulmen
Member
Posts: 41
Joined: Wed Feb 04, 2009 8:36 am

Re: 1:10 twist with 300 Blackout?

Post by Fulmen »

Dolomite_Supafly wrote:It will not stabilize 210 grain SMK's but according to the calulations it should stabilize 200 SMK's, just barely.
Don't trust calculations blindly. I've experimented with subsonic 3006, and my rifle wouldn't stabilize much more than 180 jacketed. 200grs Lee cast produced elongated holes at 50 meters. All barrels are individuals, not all will work with heavy bullets.
User avatar
Dolomite_Supafly
Silent But Deadly
Posts: 3017
Joined: Fri Oct 30, 2009 7:03 am
Location: East Tennessee
Contact:

Re: 1:10 twist with 300 Blackout?

Post by Dolomite_Supafly »

Fulmen wrote:
Dolomite_Supafly wrote:It will not stabilize 210 grain SMK's but according to the calulations it should stabilize 200 SMK's, just barely.
Don't trust calculations blindly. I've experimented with subsonic 3006, and my rifle wouldn't stabilize much more than 180 jacketed. 200grs Lee cast produced elongated holes at 50 meters. All barrels are individuals, not all will work with heavy bullets.
I have stabilized, successfully, 180 grain Sierras out of a barrel that had just shy of 11 twist. It worked out to 10 5/8 twist and the velocity was ~1,050 fps. It was also a sub MOA shooter at 100 yards. That was in a bolt gun that was chambered in 7.62x25 with a long throat to be able to use the heavier bullets.

BTW, here are some pictures of the 7.62x25 Tokarev Savage.
It is the one I used to shoot the heavy subsonic reloads as well as cheap surplus, back when they were available. The Tokarev uses a .308' bore rather than the .311" like the AK. This makes finding reloading components easy as well.

Here are pictures of the last Tokarev build:
Image
Image
Image
Image
Image
Image

The bullets are L-R: 150 gr 30-30 bullet, 180 gr Hot-Cor, 168 gr SMK and 180 gr Sierra SP. These were dummy rounds I used for chambering to ensure I could shoot them. I did actually load these and shoot them as part of my testing.

The tube is a tensioning sleeve that fits over the barrel then the muzzle nut is tightened down to tension the barrel. I first tried this on a sporter barrel 223 to try to fix a heat related drift problem and it worked great. On the other rifle after about 5 rounds the bullets would start walking and by round 10 they were 1"+ off of zero. After I tensioned the 223 barrel I could shoot long strings without any drift. It seems to work out to be similiar to a bull barrel as far as stiffness goes yet is lighter weight.

It was also cheaper to build, load and shoot than the 300 Whisper (it was built long before the BLK round was available). And as long as I stay subsonic there were no difference between the two. Reamers, dies, brass are all cheaper and available while the 300 Whisper tends to be expensive on all counts unless you decide to make your own brass but even then the dies and reamer as more expensive than the Tokarev's.

Dolomite
WWW.thegunmilitia.com

Come join the militia!
Fulmen
Member
Posts: 41
Joined: Wed Feb 04, 2009 8:36 am

Re: 1:10 twist with 300 Blackout?

Post by Fulmen »

I'm not saying it can't be done, just that barrels are somewhat unpredictable. Even with the same twist some combinations that work fine in one gun won't work in another. Just a warning.
User avatar
Dolomite_Supafly
Silent But Deadly
Posts: 3017
Joined: Fri Oct 30, 2009 7:03 am
Location: East Tennessee
Contact:

Re: 1:10 twist with 300 Blackout?

Post by Dolomite_Supafly »

The bullets are stable at 1,000 fps in a 10 twist barrel. I do need to shoot some longer ranges but at 25 yards they were making nice, neat, ROUND holes in the target. This is with a 17" barrel and the rounds are loaded using 10.6 grains of A1680.

This is using a cast bullet that is 1.363" long and weighs 230 grains. It is the Lee 300 BLK mold. They were sized to .309" and fired from a 300"x308" bore. They were lubed using Lee Alox after sizing.

I will update when I get some 100 yard results.

Dolomite
WWW.thegunmilitia.com

Come join the militia!
User avatar
Dolomite_Supafly
Silent But Deadly
Posts: 3017
Joined: Fri Oct 30, 2009 7:03 am
Location: East Tennessee
Contact:

Re: 1:10 twist with 300 Blackout?

Post by Dolomite_Supafly »

So today I was able to shoot some longer ranges using my 10 twist Savage. It has a 17" barrel with a 1" straight taper. It is threaded but I only had a thread protector in place today.

The 208 Amax's were stabile to at least 100 yards at subsonic velocities. The 230 grain cast bullets were also stabile to 100 yards. The Amax's were shooting under an inch at 100 yards but my cast bullets were 2"-3" at the same distance. I need to work on those some more. There were sized to .308" and that may be a bit small. The next batch will be shot as cast which is roughly .311". I used A1680 for these loads.

I also shot some 125's at supersonic velocities. At 50 yards they were shooting a single ragged hole. I used VV N110 for these loads.

Dolomite
WWW.thegunmilitia.com

Come join the militia!
Post Reply

Who is online

Users browsing this forum: No registered users and 90 guests