I am looking at building 6mm grendel upper. Anybody record velocities achieved with an 18-20” 6 grendel? Im trying to figure out if the 6 grendel really needs a longer than 20” barrel to better the 6 arc velocities or not.
- Thread starter Bowhunter-tw
- Start date
Which "6mm Grendel"? 6mm Predator? 243 LBC? Something else?
And which bullet?
This probably doesn't help at all, but I launch the 87gr v-max at 2975fps out of my 22" 243 LBC using LeverEvolution.
And which bullet?
This probably doesn't help at all, but I launch the 87gr v-max at 2975fps out of my 22" 243 LBC using LeverEvolution.
From my understanding 6mm grendel, 6mm AR, 243 LBC are the same chambering?
I’ll be targeting a bullet between 70-90 gr for predators.
The barrel I am looking at buying is 22” but was thinking about cutting it to 19” if the velocities will still be respectable
I’ll be targeting a bullet between 70-90 gr for predators.
The barrel I am looking at buying is 22” but was thinking about cutting it to 19” if the velocities will still be respectable
I'm not sure that they are... I think some use different bolts. For example, the 243 LBC uses a Type 1 bolt, not the Type 2 6.5 Grendel bolt.
I'd also really think it through before cutting down an AR barrel (of any kind). DI relies on (among other things) a combination of gas tube length, gas port size, and dwell time (effectively the time between the bullet passing the gas port to exiting the muzzle). If you cut the barrel down, you just messed with one variable in that equation. It may still work, but all bets are off. -- I know some found a certain Odin Works 6mm ARC combination to be quite finnicky. I want to say it was Rifle +1 on an 18" barrel.
I'd also really think it through before cutting down an AR barrel (of any kind). DI relies on (among other things) a combination of gas tube length, gas port size, and dwell time (effectively the time between the bullet passing the gas port to exiting the muzzle). If you cut the barrel down, you just messed with one variable in that equation. It may still work, but all bets are off. -- I know some found a certain Odin Works 6mm ARC combination to be quite finnicky. I want to say it was Rifle +1 on an 18" barrel.
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That is interesting, I guess I figured for any barrel over 18 it would use either +1 or 2 in a 6mm cartridge and it could be tuned with a gas block so cutting it could be adjusted for. I also was un aware of the bolt face type. I couldnt find case dimensions documented
As far as I know, they are the same chambering. At least similar enough to get good data from all of them for your question.
I have a 22" 6mm predator running 90gr Sierras at 2850 fps. I think that's my benchmark load that is pretty hot. I've backed it off using bit using varget to about 2725.
I'm using a rifle +2 gas tube, adjustable gas block, and some weight tuning on the JP SCS.
I haven't heard about the arc beating the 6mm grendel in shorter barrels. I don't think that's actually the case if you're using the same powders and bullets. The arc is a bit smaller case. You see guys hot rodding the arc and using ball powders to push them really fast but you could do that with the grendel too. I prefer more temp stable stuff personally.
I have a 22" 6mm predator running 90gr Sierras at 2850 fps. I think that's my benchmark load that is pretty hot. I've backed it off using bit using varget to about 2725.
I'm using a rifle +2 gas tube, adjustable gas block, and some weight tuning on the JP SCS.
I haven't heard about the arc beating the 6mm grendel in shorter barrels. I don't think that's actually the case if you're using the same powders and bullets. The arc is a bit smaller case. You see guys hot rodding the arc and using ball powders to push them really fast but you could do that with the grendel too. I prefer more temp stable stuff personally.
I've been observing people use the exact same powder, bullets and charge weights in 6ARC that I've been using in my 6 Grendel for a few years now and get nearly identical velocities. Not surprising, as they are nearly identical no matter what Hornady says.
I ended up buying the barrel and dies for $250, 100 rnds through it, cut by DA Van Horne local to mesa az. Figured thats cheaper than any 6 arc barrel and available at the moment. Its a 21” barrel with rifle length gas system.
Do you mean 6.5 Grendel?
OP doesn't seem to mean that at all.
Ok. Is there a 6mm Grendel? Or is that what is meant?
Yes. It's a wildcat made by necking 6.5 Grendel down to 6mm. It's good enough that Hornady pretty much straight copied it and called it 6 ARC. It's been around pretty much as long as 6.5G has existed.
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From what I understand 6mm AR (not arc), 6mm Grendel, 243 lbc are all the same. It is a 6.5 grendel case necked down to 6mm, no shoulder bump.
6mm arc is a 6.5 necked down and bumped back, reducing case capacity. Hornady couldnt just neck down 6.5 cause it had already been done. Patent/copyright issues.
Double check this info, but this is what I understand from my research. Im still tuning my upper but will post some velocities once I get it shooting right.
Edit: 243 lbc uses type 1 bolt face as pointed out earlier in the thread
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Add the 6mm predator to that list too. Simple neck down of the grendel case.