The Firing Line Forums - View Single Post - long barrel ballistics with pistol calibers

Pathfinder45 · March 1, 2014, 03:14 AM

The BBTI charts for 45 Colt don't mean much to me since all the bullets listed are are lighter than standard. I use 250-300 grain bullets for the most part. When I had a chronograph I compared a number of hand-loads in a 4-5/8" Vaquero versus a 24" Marlin. What I found was the faster burning powders like Red-Dot or W-231 would gain about 200 fps in the longer barreled rifle; while the slower burning propellants like 4227 would gain 400 fps. The powders in the midrange could be closely predicted for velocity gain relative to where they ranked in burn rate. It may be, perhaps, that a 20" barrel might launch a 250 grain bullet faster than a 24" barrel with the faster burning powders but not by much. 6 grains of Red-Dot is going to run out of steam a lot sooner than 24 grains of 4227. I think the 4227 load will still be gaining velocity in the longer barrel. Probably the only way to know for sure would be to test the longer barrel, cut it shorter, then retest with the same loads on the same location, date and temperature. Try it with your own rifle if you like, but leave mine alone. I think the difference will not be noticed by the game animals or targets.

March 1, 2014, 03:14 AM	#7
Pathfinder45 Senior Member Join Date: January 7, 2008 Posts: 3,224	I'm skeptical. The BBTI charts for 45 Colt don't mean much to me since all the bullets listed are are lighter than standard. I use 250-300 grain bullets for the most part. When I had a chronograph I compared a number of hand-loads in a 4-5/8" Vaquero versus a 24" Marlin. What I found was the faster burning powders like Red-Dot or W-231 would gain about 200 fps in the longer barreled rifle; while the slower burning propellants like 4227 would gain 400 fps. The powders in the midrange could be closely predicted for velocity gain relative to where they ranked in burn rate. It may be, perhaps, that a 20" barrel might launch a 250 grain bullet faster than a 24" barrel with the faster burning powders but not by much. 6 grains of Red-Dot is going to run out of steam a lot sooner than 24 grains of 4227. I think the 4227 load will still be gaining velocity in the longer barrel. Probably the only way to know for sure would be to test the longer barrel, cut it shorter, then retest with the same loads on the same location, date and temperature. Try it with your own rifle if you like, but leave mine alone. I think the difference will not be noticed by the game animals or targets.