velocity loss/gain

[cbourbeau32]

What would be a generic number for velocity loss or gain per inch of barrel length? I love Hodgdon's powder and data but for some reason they choose to use unrealistic barrel lenghts for some of their pistol data. For example in my powder manual they list a 10" barrel for 41 magnum pistol loads. Go figure. Thanks for any input anyone shares. Charlie

[Redhawk1]

About 28 fps per in.

[Lone Star]

General 'rules of thumb' just don't work with handguns.  It will depend on the barrel length, the bullet, the powder and the pressure level.  The most useful data comes from the same barrel and load, cutting the barrel off in increments, and then chronographing at each length.
For a .44 Magnum in a revolver using factory ammo:
Barrel..Velocity
18".......1565
16".......1570
14".......1541
12".......1539
10".......1468
8"........1434
6"........1308
4"........1181
It is interesting to note the velocity stays the same from 18" to 16".  This is in a vented barrel and may or may not hold true in a solid barrel or with different ammo.  The velocity difference between 18" and 12" is just 13 fps/inch, but between 6" and 4" it is 64 fps/inch.  Yes, the revolver started with a factory 18" barrel.  American Rifleman, March 1983

For a T/C Contender:
Barrel..Velocity
14"......1556
12"......1498
10"......1451
8".......1370
6".......1262

The solid barrel velocity difference between 14" and 12" is only 29 fps/inch, but between 8" and 6" it is 54 fps/inch, almost twice as much.  Guns % Ammo, June 1988



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[Graybeard]

It's not necessarily that simple. There are too many variables to assign a fixed fps per inch of loss/gain. Besides most times when 10" or longer barrels are used they are also not using a revolver and if you are with the barrel/cylinder gap you lose far more there than an inch or two of barrel will cost you or gain you.

[Lloyd Smale]

What bill said! Ive seen 4 inch guns shoot faster then 6 inch guns. Cylinder gap and barrel quality and powder burning rates mean as much as barrel lenght when comparing. For the most part the diffence is probably around 25-50 fps per inch in equal guns. Buying a handgun with a longer barrel to get more velocity is about a joke anyway. Anyone doing it doesnt understand how handguns kill. If you can shoot it well a 4 inch gun is just as effective in the hunting field as a 10 inch gun.

[cbourbeau32]

Thanks for the replies. This answered my question. Charlie

[WFN]

The data on the website "ballistics by the inch" is very interesting, but as previously mentioned may not be relevant data for revolvers http://ballisticsbytheinch.com/41mag.html