Post by drhenley on Sept 9, 2014 18:04:33 GMT -5
The "357 Mag Snubby Loads" thread got me thinking about some things I have noticed with short barrels.
reloadbench.freeforums.net/thread/393/357-mag-snubby-loads
One of the odd things is that a load that blackens the end of my 5" 1911 leaves the end of my 3.3" 1911 clean. That seemed to be counter-intuitive, but then I figured that the powder still had enough pressure when the bullet was exiting the short barrel that it just blew everything clear.
I have advocated using fast powders in a short barrel. Not for the velocity, but to minimize muzzle flash. I figured that a fast powder would burn more completely in a short barrel than a slow powder. I fail to see the flaw in that logic, but someone could correct me if I'm wrong...
Anyhow, I decided to test several powders in several length barrels.
So I went to the range with three different loads for 45 ACP 230 grain bullets. All are max loads:
4.5 grains Trail Boss
5.3 grains HP-38
6 grains Unique
These weren't chosen for any other reason than they are the only powders I have that are suitable, so was what I used. I fired 5 shot sample groups for each combination of barrel length and powder.
I fired test groups in a 5" Colt, a 4.2" Sig, and a 3.5" Rock Island.
There was only one major revelation. And it was a doozy. As expected the Unique load had a ferocious muzzle blast in both the 4.2" barrel and the 3.5" barrel. But what was totally unexpected was that the velocity went up with the Unique load from the 5" barrel to the 4.2" barrel. I'm still scratching my head over that.
Here is the results in graphical form. The results can be summed up: If you want faster loads in a short barrel, use a load that is faster in a longer barrel.
reloadbench.freeforums.net/thread/393/357-mag-snubby-loads
One of the odd things is that a load that blackens the end of my 5" 1911 leaves the end of my 3.3" 1911 clean. That seemed to be counter-intuitive, but then I figured that the powder still had enough pressure when the bullet was exiting the short barrel that it just blew everything clear.
I have advocated using fast powders in a short barrel. Not for the velocity, but to minimize muzzle flash. I figured that a fast powder would burn more completely in a short barrel than a slow powder. I fail to see the flaw in that logic, but someone could correct me if I'm wrong...
Anyhow, I decided to test several powders in several length barrels.
So I went to the range with three different loads for 45 ACP 230 grain bullets. All are max loads:
4.5 grains Trail Boss
5.3 grains HP-38
6 grains Unique
These weren't chosen for any other reason than they are the only powders I have that are suitable, so was what I used. I fired 5 shot sample groups for each combination of barrel length and powder.
I fired test groups in a 5" Colt, a 4.2" Sig, and a 3.5" Rock Island.
There was only one major revelation. And it was a doozy. As expected the Unique load had a ferocious muzzle blast in both the 4.2" barrel and the 3.5" barrel. But what was totally unexpected was that the velocity went up with the Unique load from the 5" barrel to the 4.2" barrel. I'm still scratching my head over that.
Here is the results in graphical form. The results can be summed up: If you want faster loads in a short barrel, use a load that is faster in a longer barrel.