Home Forums Hunting & Shooting Ask The Gunwriters Bimodal Velocity Distribution

Thanks, I may be having the same issue you were in my sub loads...

I thought of filler but was scared to try it due to the suppressor. Seems you are using it with no issues...

Great piece of work all around!

H-11 does perform well with to other much air space in my experience.

Hey rost, I believe the spent filler will be a problem. When I dropped my mag there was approximately 2 grains (volume as compared to propellent) on top the mag and in the action. I can't imagine this much crap isn't going to FU a trigger.

When I removed the can after the 10 rounds and thumped it against a surface about 6 grains dumped out. My Silencerco Havester can not be disassembled and I fear build up. Although the spent filler was not at all sticky to the touch. I suspect the filler in the action dropped back from the can to the action.

I will continue to use this load and will post if I encounter an actual issue.

I really do not recommend using filler for loads fired through a suppressor.

Also, it appears you're getting a lot of advice in this thread from people who don't shoot 300 Blackout; that is unfortunate because it's not at all the same thing as magnum revolver loads as H110 is normally used for. The "normal" behavior of H110 in revolvers is not the same as in subsonic rifle loads. Case fill isn't that low with H110 and subsonic heavy bullets, and H110 can work very well for subsonic loads to cycle an AR. A number of people on the 300Blktalk forum use it successfully, myself included. With that said, Lil'Gun and 1680 can be better choices for subsonic loads in an AR15.

If you're not using a semi-auto though, if it's a bolt action, do yourself a favor and move to faster burn rate powders. They are quieter suppressed, and you don't need the extra gas of magnum pistol powders to cycle.

If you really want to use H110, try a different primer, and try lubing your case necks. Lubed case necks can tell you if your issue is related to neck tension.

Edit - just noticed your mention of the buffer retainer spring, so you're using an AR. Trailboss and other fast powders won't cycle the action; fine if you want really quiet loads but defeats the purpose of an AR.

I run the can on a bolt gun. If I have action noise from an AR I've almost defeated my purpose.

I will have to contact pufflon and my suppressor maker.

I sure would like to get the group size down and do away with first round pop... its aggravating as hell. Group size is fine as long as its supersonic.. drop below and I mean even well below, its not great. Good enough for almost 200 yards on deer from the 300/221 but I sure wished the groups were snugger....

I post on 300blktalk as Rick. I've shared this same issue and results there. Some great guys there and one shared a tremendous spreadsheet loaded with subsonic load data. I was surprised the bimodal velocity issue was not already covered given all the subsonic load development. The issue, as very well described by Dr. Oehler, should be encountered by all users under similar conditions. Would love to share a campfire with that gentleman.

I have yet to encounter any issues with filler use other than the mess. The spent filler doesn't stick to any surfaces. It easily dumps from my receiver and can. I will continue with it's use and report any issues.

Case fill is low. I cut off a case to determine the powder level and found it impossible to seat the bullet against the charge as is suggested on 300blktalk for supersonic.

Thank you for your comments.

Saga continues.

I contacted Hodgdon about loading subsonic loads in the 300 Blackout. They recommended their CFEBLK powder.

I fired two rounds and received 948 and 836 velocities. The two rounds was enough for me to believe the powder change would not address my bimodal velocity distribution.

I agree with previous comments on not using H110/W296 for reduced loads. I've had best luck with W231 and Unique for rifle loads in the 1,000 to 1,200 fps range.

Per usual, I recommend reading this before using pistol powders in rifle cases:

http://www.gmdr.com/lever/pistolpowi.htm

Boise
Run the same test again but this time between shots raise your gun and tap it thus settling the powder the same way and see if there is a difference. it may just be where you powder is settling between shots . Good luck Cheers NC