Yeah, by asking if cutting a barrel's length almost in half would have an effect on the round's performance, I was calling the "holy grail of ballistics" into question... I wouldn't say that's an accurate summary of my question by any means. I was simply asking how much the ballistics would suffer from the reduction in barrel length. As you'll see from this scientific study, the loss of velocity is not insignificant:
http://www.ballisticsbytheinch.com/45auto.html
A 230 grain round drops from almost 900 fps out of a 5" barrel to 787 from a 3".
I think I read that correctly anyway; the statement I was responding to is composed of several fragments, and so I can't be completely sure.
I like the website you reference, but, I think you are drawing the wrong conclusion, drawing general conclusions, from specific results.
Bullet velocity out of a short barrel is determined by bullet weight, powder speed, and primer. GENERALLY, a fast burning powder, and heavy bullet can combine to get near maximum velocity in a short barrel. Now, what is in
commercial ammunition is generally the cheapest powder that will get the job done, regardless of burn rate, combined with whatever the bullet is they get the best deal on, priced as high as the market will take for the product. Even ammunition marked "For short barrels" can really suck ballistically, since the marketing is for short barrels, and, that's about it.
Your initial assumptions, based on limited data:
how effective can the ballistics of a .45 ACP subcompact gun really be? I mean, .45 ACP is already starving for velocity out of a five inch barrel, and almost cutting that length in half has got to put its muzzle velocity down to 900 or so fps even with a sub 200 gr round. Shooting +P might help some, but still... that's a slow, slow round. .380's moving faster than that. Thoughts?
And, is totally incorrect.
I would look at Doubletap, Buffalobore, and then get back to use on how bad .45 ACP is out of a short barrel.
That said, saying the 45 ACP, at slow speed, is ineffective is much like saying a 16 pound cannon ball, at slow speed is ineffective. It's simply not true. The .45 ACP, even with it's slow speed, in 230 grain ball ammo, simply has worked for longer then you or I have been alive, and very well.
Also, since when is going from a 5" barrel to a 3" or 3.5" barrel HALF????
The 45 ACP, with ball ammo, and a short barrel is VERY effective. It's a BIG, heavy bullet that penetrates, can tumble, and penetrates through the target
at near full speed, compared to a HP, which slows down and looses most of it's velocity in the first 6-10".
In other words, you have a long, wide wound channel from one entrance hole to one exit hole, without much slowing it down. Overall, this maybe far more effective then a short, quick wound channel that stops between 10-14".
Your other assertion, shooting plus P, might help, is also powder dependent. Plus P, or 45 Super, helps immensely, provided the powder is matched to a short barrel.
Here is an example of ammunition properly designed to be used in short barreled guns:
http://www.buffalobore.com/index.php?l=product_detail&p=105
S&W mod. 340PD 1-7/8 inch barrel -1,015 fps (361 ft. lbs.)
S&W mod. 66 2-1/2-inch barrel -1,097 fps (422 ft. lbs.)
S&W mod. 65 3-inch barrel -1,172 fps (481 ft. lbs.)
S&W Mt. Gun 4-inch barrel -1,232 fps (532 ft. lbs.)
Colt Python 6-inch barrel -1,198 fps (503 ft. lbs.)
As the bullet weight increases, the velocity differential between short and long barrels diminishes.
With 45 ACP 255 grain bullets, the bullet weight creates enough resistance to keep the bullet in place long enough for pressure to build quickly, giving near maximum velocity in a 3-4" Barrel.
When you get over 350 grains, in large calibers, this becomes REALLY noticeable, and, even with slower burning powders you can get near maximum velocity in 3-4" barrels.
The problem with automatics is case size. With the .45 ACP, the case is simply too small to really use anything over 255 grains effectively, read with any sort of velocity. Revolver cartridges, such as the .44 magnum and up, allow enough case capacity to use a lot of powder, heavy bullet, and get a lot of velocity out of a short barrel.
The over solution is the one Lee Jurras used: 185 grain bullet, .44 magnum, loaded with tar paper, glue, and a large charge of H110, a relatively slow burning powder. With enough powder, a ton of crimp and glue, the 185 stayed in the chamber long enough to develop nearly 1900 fps in velocity in a relatively short barrel.
So, in short, don't draw general conclusions from specific observations. That's a logical fallacy.
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