short bbl & powder burn rate

[Steve H]

As little as I know about burn rate of different powders I'm going to make a wild guess and hope someone can steer me in the right direction. Shooting a 3" bbl .45 you may have a problem with some hollow points opening up, or so I'm told. If this is true I would think that your reloads would want a fast burning powder to develop as much velocity as fast as possible. PLEASE tell me if I am wrong with this thinking. If what I'm thinking is correct can someone lead me to a list of burn rates for popular powders used in .45 loads?
Thanks Much
Steve

 

[HSMITH]

The powder that makes the top velocity in a 5" barrel is also going to make the top velocity in a 3" barrel, the same is true for a 6" barrel and a 2" barrel. Pick the powder that makes the speed you want with safe pressures.

Burn rate is about time to peak pressure, not velocity. A powder that is a little slower will push on the bullet for a longer period of time, and consequently make more velocity. Remember though, that this is all in the first inch or so of the barrel and with some powders it all happens completely in the case!!!

Your reloading manuals are all you need, pick a powder or three based on the velocity they give. From there you shoot them and chronograph them to find out what you like best.

 

[The Bushmaster]

And another example(belief). I shoot a lot of .357 magnum rounds in 2 1/2", 4 3/4" and 6 1/2" barreled handguns. I have found that Alliant 2400. H110, W-296 are just too slow of a burn rate to get a bullet up to speed in the 2 1/2" barrel. But W-231 will burn fast enough in that shorter barrel to net me magnum velocities (above 1100 fps)...One must be careful when working up W-231 to near maximum pressures though. I am allowed 8.1 grains under a 125 grain SJHP, but the maximum powder charge that the Mod 19 2 1/2" can stand is 7.7 grains. I get 1100 fps with 7.6 grains of W-231. At 7.8 grains I start getting cases that are hard to eject. Each firearm is different...

 

[Walkalong]

I can not prove it, but I believe any powder in the approximate burn range of AA#5 / WSF / H-S6 / 3N37 / SR-4756 and faster will behave very much like HSMITH descibes.

Now, I also believe for very slow pistol powders we can get bigger velocity advances in the long barrels and losses in the short ones like The Bushmaster describes.

Now, exactly where the burn speed starts changing those results? I am, of course, guestimating, although with a bit of data to back it up.

It would make for interesting study.

 

[HSMITH]

Bushmaster may well be 100% correct in his example, I have never run that exact test. I use Blue Dot for the same loads he is talking about and it makes the highest velocity in a 2 1/2" barrel just like it does for me in a4" and a 6" barrel. With light bullets in 357 magnum Blue Dot has always been fastest for me, and by a good bit. 125's will go over 1500 fps pretty easily in a 4" and well over 1400 from a 2.5" barrel. Like 231 but ten times worse though, when you get near the top it becomes VERY sensitive.


Power Pistol will probably be the 'one' for top velocity in a 3" 45 acp, 4756 will also be a strong contender. Both will be a LOT faster than you can safely get with faster powders for sure.

 

[Eagle103]

You may find this info interesting:
http://www.speer-bullets.com/pdf/ReloadingSupplementalDATA/38s135GD.pdf
The load is specifically designed for short barrelled guns yet most of the recommended powders are medium burn rate. No mention of Bullseye or even W231.