16” 6cm
- Thread starter deersniper
- Start date
Not running one but curious what’s got you needing follow up precision shots at this increased rate?
I once considered a 243Win but scrapped the project when I decided I didn’t have the ammo stash built up to feed it.
I’ve played with this idea before. I ran the ballistic numbers and just didn’t make sense. Shorter barrel, 308 or 6.5cm. The 6cm really needs the velocity to be worthwhile.
Run the numbers for your intended purpose and see if it makes sense for you.
Run the numbers for your intended purpose and see if it makes sense for you.
Craddock Precision swapped the 16" .308WIN barrel on one of my AR10s with a 16" 1:8 twist rifle length Bartlein barrel. Because of the twist, I'm running Berger 95 VLD TGTs (which are easy to get these days) at 2900fps. So far I've got about 500 rounds through it and it's been great - very accurate and reliable. The one caveat is that it was severely overgassed when I got it and broke the bolt a couple shots in. I replaced it with a JP high pressure bolt and tuned the SLA gas system and since then it's run smooth.
In an AR10 as a general purpose rifle, the 16" setup is perfect. If I was shooting 100% precision, then I would have gone with a longer barrel and a faster twist.
Edit: This rig has gone to 1200m against full IPSC steel with ease. Getting to 1400m was more difficult.
In an AR10 as a general purpose rifle, the 16" setup is perfect. If I was shooting 100% precision, then I would have gone with a longer barrel and a faster twist.
Edit: This rig has gone to 1200m against full IPSC steel with ease. Getting to 1400m was more difficult.
This is just false.
Show me a 308 round that outperforms a 108 eldm or even the cheaper 105 bthp at a given barrel length. I'll wait
Shoot, you could even chop another 2" off the 6mm and it'll still kick 308 ass.
Btw I'd love to be wrong, I've got a couple shorty 308s.
6.5 with 147s with be close, but I'd suspect gas gun mag confines and pressure limts will kill your speed and give the edge to the 6.
Not on a gas gun, but I run 16" 6cm in a bolt gun. I can answer more precise questions..but on the surface, I'm using light bullets with my reamer that was ground for shorter bullets. I am getting 3500fps with 65 vmaxes and a fast powder. I would imagine with a well tuned AR you could get close. As far as velocity with heavy bullets, I'm no help, but my setup is for predators
I'd guess 2725-2750 with 108/110s would be reasonable but would like to hear others chime in with real data. That should expand to 600 for just about anything you'd wanna kill.
Shooting gas guns is tough though, man. Way less forgiving than a bolt gun or even an AR-15.
You're also going to want a super low back pressure can like the oss because you'll already have crazy high pressure at the gas port. If you run an agb the window where it ejects probably will be tiny. Stay away from middy's. I'd run nothing less than a rifle length, even if the port is up by the muzzle.
I know guys say they can run tbacs and whatnot but IME (308s and 6.5cm with a Nomad-L) the gun gets dirty and dry way too fast and is just a general pita to tune.
Tbh I don't really see the point these days with 6 Arc or 22 grendel for hand loaders.
Shooting gas guns is tough though, man. Way less forgiving than a bolt gun or even an AR-15.
You're also going to want a super low back pressure can like the oss because you'll already have crazy high pressure at the gas port. If you run an agb the window where it ejects probably will be tiny. Stay away from middy's. I'd run nothing less than a rifle length, even if the port is up by the muzzle.
I know guys say they can run tbacs and whatnot but IME (308s and 6.5cm with a Nomad-L) the gun gets dirty and dry way too fast and is just a general pita to tune.
Tbh I don't really see the point these days with 6 Arc or 22 grendel for hand loaders.
I never said it outperforms 6mm. I just simply stated that for 6mm it just didn’t make sense when the whole point of 6mm is the speed. If you don’t need high velocity numbers, than a shorter barrel in 6.5 or 308 just makes more sense since the bullets are heavier with good/decent BC.This is just false.
Show me a 308 round that outperforms a 108 eldm or even the cheaper 105 bthp at a given barrel length. I'll wait
Shoot, you could even chop another 2" off the 6mm and it'll still kick 308 ass.
Btw I'd love to be wrong, I've got a couple shorty 308s.
6.5 with 147s with be close, but I'd suspect gas gun mag confines and pressure limts will kill your speed and give the edge to the 6.
This may not make sense for the OP which is why I said it depends on what you want.
