Barrel length relation to velocity?

[TEX]

Don't know if this is the correct forum for this question, but here goes.

I recently looked at a Beretta Storm Carbine in 45ACP and really liked it. This carbine has a 16.5" barrel and I was curious as to how much additional velocity it might provide. I know a 200 grain Speer +P load will move out at about 1000 fps in my 5" Kimber pistol, but I would like to know how much extra velocity an additional 11.5" would provide. Does anyone know if there a way to calculate the increase in velocity that would result by trippling the length of the barrel, which the Storm would do, or a web page available that does it. I would also think that at some point, the barrel could be too long for a pistol cartride, and would actually start scrubbing speed off the bullet once the powder had done its work, but I have no idea where that point would be although I think it might be in excess of 24"s.

Thanks - TEX

 

[strambo]

Don't know of any resources of hand with formulas or anything. It's not a linear relationship though (like "X"fps per inch). Lots of variables too. A faster powder from a smaller cartridge will have less increase then a slower burning powder from a larger cartridge. As you said, at some point, the powder is completely burned and maybe nearly expanded fully in the long barrell and the bullet is just coasting.

I'd guess you could expect 1200fps or so. A chrono, even an inexpensive one, ($80 shooting chrony) is very valuable.

 

[joneb]

Seirra has load data for the Marlin camp 45 . With a 230 grn FMJ ,max velocity was 800 FPS for a 200 grn 1,100, and a 185 grn achieved 1,250 fps Some of the powders they used were Unique, Blue Dot and AA#5

 

[Archie]

Powley Computer

is what you want.

The velocity of a given load in a specific length barrel is dependant on the ratio of powder charge to bullet weight, and the ratio of total volume in the chamber only to total volume in the chamber and barrel.

The Powley Computer is the invention of Homer Powley, a ballastician and mathematician. There is a website that has a little information: http://www.geocities.com/nelstomlinson/sliderules.html

Powley discovered the basic math that makes all the modern loading programs work.

Along with powder charges and suggested powders, it has a section to estimate muzzle velocity using the factors I mentioned in the first paragraph.

I've got one around someplace, if I can ever find it.

 

[Clark]

I just plug in the bullet part number, powder, charge, over all length, moly coated or not, and barrel length, and Quickload will give me the velocity, peak pressure, muzzle pressure [noise], wind drift, drop over distance, energy, % powder burned, etc.

I am the bottom 1% of computer savy for electrical engineers, and I can install Quickload and I use it now instead of my ~50 load books, The velocities it predicts are in the middle of the spread of what my chrono measures about half the time.

http://www.neconos.com/

 

[griz]

Can the program find the barrel length for max velocity or do you have to narrow it down by trial and error? I'm just wondering how much barrel a 45 would need bfore it starts slowing down.

 

[dfaugh]

Check on this thread, crrently in the "general discussion" area. It also has references to a few other threads on the subject:

http://www.thehighroad.org/showthread.php?t=215654

 

[strambo]

I was just messing with the quickload demo and I couldn't get the 7.62 Tokarev to slow down in a 200" barrel. I don't think the program accounts for barrel friction. It would probably be pretty accurate showing the expected velocity increase in your carbine though.

 

[Jim Watson]

Quickload and I use it now instead of my ~50 load books, The velocities it predicts are in the middle of the spread of what my chrono measures about half the time.

What does it show the other half of the time?
I am not a high-end experimenter, but it looks like it could be informative if dependable.