Dear Adobe Walls,
My 1954-vintage Model 99 EG .300 Savage with a 24" barrel produces about 50 fps more velocity with the same factory 150-grain loads and about 40 fps more velocity with the same 180-grain factory loads when compared with my wife's Remington 700 (early 1990's manufacture) in .300 Savage. Two rifles, of course, do not make a rule, and this is a bit of an apples to oranges comparison. My experience, however, with this pair of rifles and also with other rifles in different chamberings having differing barrel lengths leads me to believe that RAM is again right on when he writes that the velocity loss is considerably less than 100 fps per inch of barrel shortening.
In Remington ammunition catalogues, there is a formula to calculate velocity change in relation to barrel length. The calculations vary depending on the original muzzle velocity at the standard 24" length. Faster cartridges are said there to lose velocity a little faster. My experience (admittedly limited) suggests that the Remington formula is roughly correct. I stress "roughly," and I note that each barrel is a law unto itself. My son & I have two identical Marlin 336 Cowboys in .38-55, with 24" barrels. With identical (slow) Winchester factory ammuntion, there is as much as 40 fps variance from rifle to rifle. With the hotter Buffalo Bore stuff, there is less variation, which is the reverse of what you would expect from the Remington formula. I think the Buffalo Bore stuff is just more consistent round to round.
Also, I have a Winchester Model 71 carbine (20" barrel) that does only 5 fps less than a Model 71 rifle with 24" barrel, using ammo from the same box of Winchester factory 200-grain .348 ammunition.
Finally, with handloads, using powders of different burning speeds can help mitigate velocity loss in shorter barrels.
I don't know if that is much of a help. Good shooting!
Redcoat
