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Gyrogearhead wrote:Ya know, reading the above reminds me of something I've been wondering about for quite a while and talking about among my shooting friends. My favorite caliber is 45ACP and I've been reloading for several years now. I have used 7 gn AA#7, 6.2 gn AA#9 and 5gn Bullseye powders under a 200 gn LSWC and have noticed a distinctive difference in felt recoil from the three powders. The AA#9 gives the strongest recoil and the Bullseye gives the lightest. I load all three to chronograph between 890 and 910 fpm so the three powders are giving the bullet very close to the same muzzle energy.

I'm wondering if the faster burning Bullseye has nearly finshed expending its entire energy on pushing the bullet by the time the bullet has reached the muzzle while the other two are still burning after the bullet has exited the muzzle?

What brought this to mind is the comment from bystanders that with Bullseye there is not much of a muzzle flash while with the AA7 it is around three feet and with AA#9 it around 9ft ( eyeball estimates after sunset). If that's the case then the difference in felt recoil could be due to the "rocket engine" effect of the burning powder in a barrel the bullet has long departed.

If this is the case it would seem to me that it would just be "wasting fuel" to use a slow burning powder that continued to burn outside the barrel and after the bullet had exited the muzzle. Idealy I think one would choose a powder to suit barrel length such that the charge was completely burned up just as the bullet exited the muzzle.

Am I missing something here?

Gerry