I currently use a suppressed 16 inch 6x45 AR15 for calling and really like it but would like a little more power. I have all but decided on the 6x6.8 but am trying to get a better feel for how much more velocity I should expect over the 6x45. For comparison's sake, I am currently getting 3225 fps with 55 grain nosler ballistic tips and would like to know what velocity I can expect with the 6x6.8 with the same bullet in either a 16 or 18 inch barrel. Are any of you using the 6x6.8 with 55s in a 16-18" barrel, and what velocity are you getting? Thanks!
6x6.8 barrel length and velocity with 55s
- Thread starter JDF_GSP
- Start date
Just to give you a close idea I’m running a 22” 6x6.8 with 58s at 3550 with h322. I would think you would be 3400-3450ish with the same powder. When I used 8208 with the 58s they only shot 3450 so I picked up 100fps with h322. I think they usually say about 25fps per inch of barrel to figure it out.
steve garrett
Well-known member
get a 6DTI, I shoot 55's at 3525 fps from a 20" barrel, h322 or tac, will get you there, I have had better luck with TAC, its got more plateau when run full house. h322 spikes more when it gets up to max.
8208 and benchmark are too slow for this case and bullets under 60 grains. you simply run out of case room before you can approach top speeds.
8208 and benchmark are too slow for this case and bullets under 60 grains. you simply run out of case room before you can approach top speeds.
DiRTY DOG
Well-known member
Originally Posted By: steve garrettget a 6DTI, I shoot 55's at 3525 fps from a 20" barrel, h322 or tac, will get you there, I have had better luck with TAC, its got more plateau when run full house. h322 spikes more when it gets up to max.
8208 and benchmark are too slow for this case and bullets under 60 grains. you simply run out of case room before you can approach top speeds. My 22" 6DTI runs 58gr Vmax @ 3560fps with 31.5gr 8208. It's not a compacted load but it's very close. Same for the 55gr NBT-LF.
8208 and benchmark are too slow for this case and bullets under 60 grains. you simply run out of case room before you can approach top speeds. My 22" 6DTI runs 58gr Vmax @ 3560fps with 31.5gr 8208. It's not a compacted load but it's very close. Same for the 55gr NBT-LF.
I've not shot 55's but a ton of 58's. Most of my loads leave a bit of room as I do like case life and none of these have been hurting me there. These were shot at temps up mostly between 85 and 105 on various days. Accuracy was more than good. The TO barrel Rich is selling is obviously faster than the BHW tubes. Perhaps the five land polygon rifling is at work here.
18" Tactical Ordnance barrel
H335 3546 31.5
8208 3419 32.0
748 3550 33.5
18" BHW
8208 3403 31.5
H322 3455 31.5
20" BHW
H4895 3363 32.0
748 3550 33.5
8208 3425 31.5
Greg
18" Tactical Ordnance barrel
H335 3546 31.5
8208 3419 32.0
748 3550 33.5
18" BHW
8208 3403 31.5
H322 3455 31.5
20" BHW
H4895 3363 32.0
748 3550 33.5
8208 3425 31.5
Greg
Originally Posted By: GLShooterI've not shot 55's but a ton of 58's. Most of my loads leave a bit of room as I do like case life and none of these have been hurting me there. These were shot at temps up mostly between 85 and 105 on various days. Accuracy was more than good. The TO barrel Rich is selling is obviously faster than the BHW tubes. Perhaps the five land polygon rifling is at work here.
18" Tactical Ordnance barrel
H335 3546 31.5
8208 3419 32.0
748 3550 33.5
18" BHW
8208 3403 31.5
H322 3455 31.5
20" BHW
H4895 3363 32.0
748 3550 33.5
8208 3425 31.5
Greg
Do you have any remembrance of how the accuracy was on those loads Greg?
18" Tactical Ordnance barrel
H335 3546 31.5
8208 3419 32.0
748 3550 33.5
18" BHW
8208 3403 31.5
H322 3455 31.5
20" BHW
H4895 3363 32.0
748 3550 33.5
8208 3425 31.5
Greg
Do you have any remembrance of how the accuracy was on those loads Greg?