H4198 (or faster) powders for AR pistol loads?

[Typetwelve]

With the existence of rounds like 350 Legend or 300 AAC...there's no reason to think that super short barrel AR's can't get solid performance. The issue seems to be that with either 300 AAC or 350 Legend, they use much faster burning powders like H110, CFE BLK, or IMR4227. While not "fast" in the pistol world, they are much faster burning than the typical powders used for 223 Rem, like Varget, CFE 223, etc.

I did notice that Hodgdon lists loads for H4198 that is, according to my burn rate sheet, #76 (H110 is 63, CFR BLK is 70, IMR4227 is 65). Compared to Varget (108) and CFE223 (111), H4198 seems like it might work much better in a sub 10" AR barrel. Any thoughts on this?

Second, has anyone messed around with even faster burning powders for this purpose?

 

[Kaldor]

The 4198s will work but the velocity ends up being a little low. The big issue with the 4198s is that on longer length gas systems sometimes some rifles dont have enough port pressure with the 4198s to fully operate the action. On a shorter gas system is less of an issue.

I would not load anything faster burning than that unless you are specifically trying to load single shot subs, which in that case I think there is data out there using TiteGroup, Trail Boss and Clays.

 

[Charlie98]

I'll echo what Kaldor said... although I don't have direct experience with IMR4198 in the AR, I have researched it... from what I gather, it works well enough in pistol-length AR gas systems, and sometimes carbine-length systems, but is not reliable in middy- or rifle-length systems. I use a lot of IMR4198 in other rifle cartridges, so I was interested in using it... but have since abandoned the idea... there are far better powders for the AR, starting with IMR3031, the next step up in burn range.

FWIW, the numerical ranking of powders on the burn rate chart doesn't tell you everything... some powders are very close (or even identical,) and some are quite far apart, even though they may be close on the list. I've found a better chart that lists them in relationship to each powder, the first time I saw this chart, the light went off in my head about how I think of powders and burn rate... maybe it will help you.

http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf

...and another linear chart that is far more involved...

http://www.theballisticassistant.co...11/Powder-Relative-Burn-Rate-11-29-2020-1.pdf

 

[243winxb]

Used IMR4198 in 14 1/2" barreled Carbine with 55, 52, 50 gr bullets. Worked well with the 1-12 twist barrel.

Port pressure can be an issue, as said above. Faster powders will burn better in shorter barrels. Less unburnt powder exiting the muzzle. (Military test showed .5% to 5% unburnt powder exiting the muzzle.)

Faster powders then 4198? No idea. I have not tested them. 1999 IMR DATA-CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

 

[Charlie98]

As an aside... the data 243 posted likely doesn't take into account port pressure on an AR, much like generic .308 and .30-06 data doesn't take into account port pressure on the M1a and M1, respectively. It may be within SAAMI parameters, but not necessarily healthy to said gas system components. YMMV.