velocity question /barrel effect

[Malone]

What would my velocity drop be if i took a 30-30 from 20 inch to 16 inch? and if you use a program can you tell me which load you used please?

[200Apples]

Ballistics By The Inch was one such project. They tested mostly handgun ammunition but also in carbine barrels. You might look at their lone centerfire rifle, .223, data and extrapolate from that.

BBTI is no longer active but claims they will maintain the site and the test results data.

Too, you might check some of their ancillary links. Good luck.

Off the top of my head I'd say you'd lose maybe 50 fps per inch for .30-30 but that is indeed a W.A.G.

[kcheung2]

You’ve given too little information. What’s the powder used? Charge weight? Projectile & weight? It’s ballistic coefficient? Even atmospheric conditions and altitude affect it. Velocity at muzzle or at a specific distance?

But for a very approximate rule of thumb, the 50fps/inch given above is good for most rifle cartridges & barrel lengths from about 12” to 24”. But keep in mind it’s only approximate and most importantly it’s not linear. In other words the 2 inches going from 12 to 14 isn’t the same as 22 to 24.

[Tommy Gun]

Anecdotal but when I changed out an 18" to 22" for my .308 AR i went from 2680fps to 2900ish using 150gr FMJBT with 2460 powder.

[Imageview]

Look at 30-30 data in Lyman, 200-350 fps from 22" to 14" barrels in their load data. Not identical loads, but was with same projectile at least.

[M1A Rifleman]

Figure about 100-200 fps less per inch as a rough estimate.

[plumbum]

Found a post reviewing the Winchester Trapper carbine:

https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/2781813/Winchester_M94_Trapper_Range_R