New 10" barrel, bullet stability problems

[snipecatcher]

Different twist rates, so no. My machinist said the barrels were well made and couldn't find any faults, other than the bores were a bit bigger than expected. Usually a .300+ gauge fits very snug, and it had some wiggle room in both barrels, but he said it shouldn't have that much of an effect. The only thing he said was that he didn't see how a 10" barrel could stabilize those long bullets, regardless of the twist. People ARE shooting heavy subsonics through short barrels, correct? I know I've seen 7-10" barrels, but I've never seen targets associated with these barrels. Anyone care to post up a group shot with a short barrel and heavy subsonic loads? I'd like to see if there is any indication of them being unstable. I'm going to try some 150 grain 30/30 bullets and see if they are stable.
-Dan

[Hoser]

Originally Posted by snipecatcher

Different twist rates, so no. My machinist said the barrels were well made and couldn't find any faults, other than the bores were a bit bigger than expected. Usually a .300+ gauge fits very snug, and it had some wiggle room in both barrels, but he said it shouldn't have that much of an effect. The only thing he said was that he didn't see how a 10" barrel could stabilize those long bullets, regardless of the twist. People ARE shooting heavy subsonics through short barrels, correct? I know I've seen 7-10" barrels, but I've never seen targets associated with these barrels. Anyone care to post up a group shot with a short barrel and heavy subsonic loads? I'd like to see if there is any indication of them being unstable. I'm going to try some 150 grain 30/30 bullets and see if they are stable.
-Dan

I have shot lots and lots of ammo through my AR. Most of them 220 or 175 Sierras. A few 240s and some 125s. Velocities from the subs were 900-1100 fps. It is a 9.0 inch Noveske 8 twist with a Shark can.

My 300 bolt gun shoots the 220s well under MOA all day long. It is a 16.25 inch 8 twist, Lilja stainless barrel on a Remington 700 and SureFire 338 can.

No stability issues in either.

[TCCrewchief76]

Once spin is established, it shouldn't matter how short the barrel is. Again, it's time to slug the bore and see where things are for sure. I'm a bit surprised that the bore is as sloppy as it is on the lands. That's gonna have an effect on how much grip the bullet sees. Try and recover a projectile and see what kind of impression the rifling is leaving.

Kevin

[Mike Bell]

I just read a precision handloading book that it doesnt matter the length of the barrel or fps....the twist is the twist. If you go faster or slower, its still the same revs per distance.

[rsilvers]

fps matters as that is what makes the rpm go up or down.

As for barrel length, it does not matter for gyroscopic stability but there are other forces acting on the bullet - such as the muzzle blast. Very short barrels don't seem to be as accurate as normal barrels.

[alorton]

My barrel is a 10.5" Noveske and it shoots 208gr Amax's and 240 SMK's fine. I think the AAC Blackout barrels are going to be 16" or 9" and I've not heard of any of those having problems with stabilizing bullets. Short barrels have been used for years with 300 Whisper in the T/C pistols as well.

The length shouldn't be the problem.

[Mike Bell]

Sorry if Im a little slow...but this stuff is realitivly new to me because it never mattered before (to me) now that I have built a 300 wtf ever we call it....Im trying to learn everything around this stuff. So...

RPM's increase because FPS increses, but the twist rate is the same. So if he has to maintian around 1000pfs for subsonics loads....he would then have to increase the twist rate. But his twist is within the proper rate.

Was this barrel chamber recut to the 300 BLK from a whisper or 30/221 chamber before? Im wondering if the longer throat is forcing the bullet out-of-wack? OR.......

And Im wondering if it was not a regular 30 caliber barrel? maybe a .302 or .303 barrel?


After re-reading to entire thread twice.....two different barrels are making me think that its not the gun...but the relaoding set up. Have you tried ammo made by someone else??

This sucks for you Snipecatcher, but I think some of us are learning alot.

[snipecatcher]

I shot some 160 Hornady FTX bullets today. They are the 30/30 bullets with a rubber nose, and are fairly short. I only tried 2 charge weights, and ended up around 1200 fps. They were stable at 50 yards. I also loaded up some 90 grain XTP pistol bullets. They are the only bullet I've tried that will not feed. I was single loading them. They were all stable. The lightest load had them around 1000 fps, and 16 grains of VVN110 had them going 2000 fps. The supersonic load went through one gallon jug of water and stopped in the second. Retained weight 58 grains, expansion to over 1/2".

As far as my loading process goes, I really don't think that's it. I've been using the same Redding dies that I used for my 30/221 bolt action. Only one load I shot through the bolt action wasn't stable, and it was a 155 pushed by Red-dot to around 600 fps. Those hit the target completely sideways. Other than that, I never had a problem stabilizing any load in that barrel.

[snipecatcher]

Also, I'm sending my 1 in 8 twist barrel off to Hoser sometime this week. He is our resident ammo expert, so maybe he can come up with something that works. I'd really just like to get this figured out for the good of all. Also, it's driving me insane.
-Dan

[fasttwist]

I have a .308 winchester in a 10twist that wont stabalize anything subsonic. When I recovered a bullet I noticed I have what apears to be a high land in the barrel. On the other side of the bullet the baring surface is smeared = shitty chamber job. This maybe forcing the bullet into the rifling at a strange angle. I would try to catch a subsonic projectile. I would also try a bullet of a larger caliber-.310-.311.