300 AAC 245 lead subs/H110

[verdugo60]

Just getting into the 300 blackout, not worried about loading H110 and 220 smk's, because I know those work, but just got some 245 grain Missouri Bullet Co lead ones for cheaper subs than the SMK's. Wondering if anyone has gotten them to cycle with W296/H110 OR IMR 4227 as those are the powders I have. I'm sure A1680 would be better, but don't have any. So if you have used either of these powders with this or a similar bullet please give me the info.

I'm planning to start with a COAL of 2.12" and 9.5 grs H110 and go from there. Will be shooting in a 10" upper with pistol gas system. Hoping these will cycle well and lock bolt back on last round, as well as stay subsonic and stabilize through my can. Going to test first without can of course, for stability.

 

[bachelorjack]

H110 is erratic when it comes to sub loads. This has been documented.

 

[verdugo60]

Could you elaborate por favor?

 

[phreakmode]

H110 does not have the density to case fill at subsonic load levels, catastrophic failure at minimal case fills is possible, though not probable. The burn may have a wide variation from round to round based on powder settle location in the case. H110 is a fast powder and as such is suited for super sonic 125gr and under for best performance.

 

[verdugo60]

I don't think Hodgdon would list it as a sub load if it was really that likely to cause a catastrophic failure. I do see why that would make your ES higher though. Guess I should have jumped on A1680 when I had the chance, it just sucks paying HAZMAT for a pound or two of powder.

 

[phreakmode]

I don't think Hodgdon would list it as a sub load if it was really that likely to cause a catastrophic failure. I do see why that would make your ES higher though. Guess I should have jumped on A1680 when I had the chance, it just sucks paying HAZMAT for a pound or two of powder.

I never said it was likely sir.

 

[rjacobs]

I will second that H110 does some funky things when it isnt in the high 90% case fill.

I ran into weird pressure issues trying to run H110 with 147g/150g FMJBT's WAY before I should have. I talked to a guy who has loaded a ton(quite possibly literally 2000lbs) of H110 with all of the revolvers he shoots and he figured the case fill wasnt nearly high enough and he wouldnt recommend it. He said he has seen H110 blow guns up with reduced loads which, in theory, shouldnt happen.

R7 is another choice for subsonics and it is quite similar to A1680. Also 4198 is supposed to be a good sub powder. Of the H110 or 4227 that you list, I would go with the 4227 as its a bit slower and SHOULD, in theory, yield better results.

And good luck with those MO Bullet Company bullets, I had no luck with them since they hang up on the feed ramps due to the flat nose on them being wider than the feed ramps.

 

[verdugo60]

True enough. Thanks for the info sir.

 

[verdugo60]

I will second that H110 does some funky things when it isnt in the high 90% case fill.

I ran into weird pressure issues trying to run H110 with 147g/150g FMJBT's WAY before I should have. I talked to a guy who has loaded a ton(quite possibly literally 2000lbs) of H110 with all of the revolvers he shoots and he figured the case fill wasnt nearly high enough and he wouldnt recommend it. He said he has seen H110 blow guns up with reduced loads which, in theory, shouldnt happen.

R7 is another choice for subsonics and it is quite similar to A1680. Also 4198 is supposed to be a good sub powder. Of the H110 or 4227 that you list, I would go with the 4227 as its a bit slower and SHOULD, in theory, yield better results.

And good luck with those MO Bullet Company bullets, I had no luck with them since they hang up on the feed ramps due to the flat nose on them being wider than the feed ramps.

Thanks for that info, very good to know. I'm thinking the reason people have gotten away with the H110 and 220 SMK combo is that it takes up so much of the dang case being a long match bullet. That would help eliminate the under-fill issue. From what I understand copper jackets seem to slide down bores with less resistance too.

I may just not use the H110 with the lead cast ones and hunt around for some RL7 or more appropriate powder for that bullet. The MBC is shorter than the SMK, so I think I will skip asking for that kind of a "learning experience!"

The IMR 4227 did work great in my brother-in-law's 10" DD blackout upper with the 220's. Didn't chono but they cycled unsuppressed and am pretty sure they were subsonic. He has a pistol length gas system, which seems to be the way to go with the Blackout, especially a shorty.

 

[rjacobs]

IMO every blackout barrel should be a pistol gas system. It allows them to actually run due to the increased gas pressure available. The blackout loses its gas pressure really quickly compared to a .223 gun because the bore is obviously much larger. The pistol gas system takes advantage of this and doesnt beat the hell out of the gun like it can on a 223 gun. 99% of the issues I see with guy's uppers is a carbine gas'd, 16" barrel that wont run anything, let alone supers and not subs. Gas port is generally WAY undersized. When I build 16" uppers with carbine gas for guys I open up the gas port to .110-.125(depending on their gas block and gas tube ID's) no matter what the "manufacturer" has spec'd it. Most guys bring me cheap ass barrels where the "manufacturer" isnt really the "manufacturer" and they are just re-selling, but they have done no research or r&d to see what the proper port size is to be able to tell the real "manufacturer" what to drill. Most guys just spec a .223/5.56 spec port size(my guess only, but after measuring quite a few, its an educated guess) which is WAY WAY small for the blackout and its pressure curve.

Anyway, off my rant there.

Have fun and let us know if you get those MBC bullets to function.