Faster Burn vs. Slower Burn Powders

[345 DeSoto]

All things being equal, should I use a faster or slower burning powder in a longer barrel (eg. 5" vs.16" barrel)? I'm trying to work up a good accurate load for a 185 grn bullet in a longer than average barrel (.45 ACP), but am wondering which burn rate of powder I should be looking at...maybe even a rifle powder. I know the burn rate HAS to make a difference in a 3 times longer barrel...

 

[stubbicatt]

You might get better velocities with the slower powders, and even better accuracy. Most non magnum pistol powders have very nearly completely burned before the bullet has left the casing. If you have access to a chronograph, it would be an interesting experiment to run 10 shots each of fast and slow powders through a pistol over the chronograph, and 10 shots each out of your carbine over the skyscreens, and see what the velocity differences are. There might be quite a bit to learn there.

I know that my old Marlin lever rifle in 357 magnum shooting 158 grain bullets was almost 2000 fps, nearly 30-30 territory for a similar weight bullet, this with 2400 powder.

 

[joneb]

Is the 16" barrel a straight blow back semi-auto ?

 

[Ol` Joe]

The powders that give the best velocities usually do so reguardless of barrel lenght. Pick a good load/powder from your manual and go from there.

 

[Walkalong]

AA #7, Blue Dot, or Enforcer to try to get max velocity from a longer barrel in .45 ACP, but Ol' Joe had some very good advise. You may get a little more velocity, but it will be at the expense of a good bit more recoil. The .45 ACP is not a barn burner, wasn't meant to be.

 

[345 DeSoto]

Jibjab...yes, straight blowback semi-auto.
I'm not necessarily looking for higher velocity, but a powder best suited to utilize the longer barrel length, for improving accuracy...

 

[Walkalong]

I'm not necessarily looking for higher velocity, but a powder best suited to utilize the longer barrel length, for improving accuracy...

Then go with Ol' Joe's advise.

 

[joneb]

I have a Marlin Camp 45 and for 185gr Nos JHP Unique and AA#5 have given me the best results, slower powders with this bullet weight produced cycling problems even with WLP and a snug taper crimp. For 230gr jacketed HS-6 will work, I have also used Blue Dot for this bullet weight with mixed results. Unfortunately the straight blow back limits the ability to achieve higher velocities through the 16" barrel, for a 185gr jacketed bullet 1,250fps is about tops.
I almost forget to mention that I recently installed a heavier recoil spring in my Camp 45 (16 lbs) from Wolff which I like, the brass is not flung as far and it may help slower powders to peak faster.

 

[345 DeSoto]

Jibjab,
I've installed a 22lb Wolff in my Marlin 45, but haven't fired/loaded for it yet with that spring. With your info in mind, about recycling problems with the Stock spring, I will work up some loads for the 185 HBRN Berrys. I have some Unique, which appears to be the powder of choice for most, and will start with that. I use it for my 1911 and it works quite well with the 5" barrel. Maybe the heavier recoil spring will allow more efficient use of the 16" barrel. It MIGHT be the key to the whole thing...

 

[Marlin 45 carbine]

jibjab and DeSoto I also have a Marlin Camp - interested to see what velocitys are obtained and how accuracy is affected as well. I don't have a chrono so am sort of 'playing it by ear' with safety in mind of course. do you use new brass for these loads and is it rated +P?
I have installed the Blackjack buffer and 21lb spring. the factory buffer isn't very durable.
I'm not really looking to 'magnumize' the cartridge but to step up velocity while maintaining best accuracy. so far it seems 'power pistol' is the best but all I've loaded otherwise has been Bulleye and WST.
I've had great results with Golden Saber 185 and Hornady C/T 200's.

 

[joneb]

I have not loaded plated hollow base in my Marlin Camp, I would check with Berrys for a max pressure/velocity for this bullet, my concern would be that part of the bullet could be left in the barrel, if loaded to hot

 

[345 DeSoto]

Good idea, Jibjab...