Best temp stable powder for subsonic?

[lovdasnow]

Ok, hopefully this hasn't been gone over to much. I went through all the pages on here and read them looking for the best all around powder.

so I guess the question is: What is the best all around powder for a bolt action 300 whisper shooting subsonic rounds? leaning toward the 220-240gr SMK's.

looking for accuracy, safety, temp senstivity, etc

thanks a lot. Jon

[lovdasnow]

ok, should I just go with AA9. just wasn't sure about temp stability?

[Artful]

I can't do just one powder :rolleyes:
But when I get to that bullet weight my list to play with is
(information from internet so watch yourself...as always start up and work down to get under speed of sound without sticking a bullet in your bore)

2400 (8.6 with 250 for 1011fps)
4227 (9.2 with 220 for 1006 fps and 9.3 with 250 SMK for 1039 fps)
H110 (9.1 with 220 for 1061 fps and 8.9 with 250 SMK for 1052 fps)
AA#9 (8.8 with 220 for 1071 fps and 8.8 with 250 SmK for 1040 fps)
AA 5744 (9.9 with 220 for 1087 fps)
AA1680 (10.3 with 220 for 1023 and 10.3 with 250 SMK for 1013 fps)

My experience is all powders are sensitive to a degree - I don't use H110 much due to that fact (I'm in AZ and shoot at just from about sea level to 6000 ft + in temps ranging from freezing to 130+) - your best precaution is to have ammo in a box out of the sun to avoid problems.

[pug]

Also check to see if powder is double base (has nitroglycerin added) or single base (just nitro cellulose). Double base will give you maximum velocity for a given chamber pressure due to the nitro added but is considered a little more touchy. Single base velocity is a little slower at the same pressure but is considered more temp stable. Not always the case but kind of a general rule. My bench has 15 different powders on it right now and I feel kind of limited :).

[lovdasnow]

thanks guys, sounds like i might just buy a couple and play around with different loads. also, thanks for the double/ single base info, good to know.

think I'll get some AA#9, and some 4227 to start with unless someone else has a better idea.

i really need to get a chrono bad, been putting it off for a while now.

[Artful]

thanks guys, sounds like i might just buy a couple and play around with different loads. also, thanks for the double/ single base info, good to know.

think I'll get some AA#9, and some 4227 to start with unless someone else has a better idea.

i really need to get a chrono bad, been putting it off for a while now.

here's an interesting link about double vs single
http://www.gmdr.com:80/lever/lowveldata.htm

look at my last two postings in Subsonic .308 with trailboss for why you need a chrono before you stick a bullet in the bore :eek: