ONEIDA, I have no quantitative data to share. However, I've found that the muzzle device you use makes a huge difference. I shot my 12.5" 6.8 with a muzzle brake one day without ear protection and blew my ear drums out. If you are shooting suppressed, then the muzzle device is contained. I have no issue shooting suppressed without hearing protection up to 300 WinMag. When standing beside someone shooting suppressed, even 5.56, I need ear protection is they are supersonic. If you are not suppressed, maybe consider a Noveske Flaming Hog.

The difference in velocity between my 12.5" and 16" 6.8s has never been a consideration inside 200 yards.

 

I have a noveske 7.5 6.8 SBR. Ill post some velocities as soon as i get some time to go shoot. I shoot 85 gr MPG and 90 gr TNT. I do make specific loads using faster burning rifle powder for short barrel 6.8 so youll have to take that into consideration.

 

Much appreciated.

 

My shortest barrel is 12.5 ARP, with just a thread protector is was loud as hell. A linear break made a big difference but I still wouldn't want to shoot it without hearing protection. I use CFE black for light bullets I'm getting 2830 fps with 90 grain gold dots and 90 tnt's.

 

My 8.5" without suppressor is oppressive to shoot but anything in 6.8 or 5.56 that's 12.5" or shorter is loud. A good flash can like a Noveske Flaming Pig is best I have found to direct sound impulse away from operator. I have two short barrels with Flaming Pigs and if have to fire without ear protection won't blow ears drums out. Of the roughly fourteen 6.8s 14.7" and under all but two have suppressor adapters and don't run them without screwing on a can.

I only have a couple 14.7" or shorter 5.56 rifles that don't get suppressors threaded on most of the time and my few short 5.56 without suppressor adapters have Flaming Pigs. You can look up Db info but is it measured in front, beside or behind gun? I have a 7.5" 5.56, 8.5" 6.8 and they stay in safe most of the time. Prefer 10.5", 11.5" and 12.5" as my short tube rifles.

If carrying a short barrel how much trouble is it to have a set of ear plugs? When I go in grocery store I stick my Walker Bluetooth hear through ear plugs in. If gunfight breaks out have plugs in ear and can press the 911 button on phone and be able to talk to emergency services, work my duty pistol and not blow my ear drums. I have three sets (three generations of the ear buds now) and put a pair in my pocket every morning as part of my EDC kit. Stuff them in ears in store or running saws at work allows me to answer phone if wife calls and not damage ears any more than already have.

Without a suppressor or ear protection prefer not to send rounds anymore. Too many good ear bud Bluetooth enabled options along with electronic muffs for range or hunting. Have a pair of Walker Quads with four microphones that make me twice as effective in the woods as can hear every little thing and if have to set off a belted magnum not deaf for two days.

 

90 grain gold dot over reloader 7 clocks 2450 fps at 10 ft from LWRC 8” PDW. Zero at 50 yards put it at zero again at 150 yards. 3.2” drop at 200 and 18.4” drop at 300. Velocity is 1498 fps at 300 yards according to ballistic AE.