[klingy]

Has anyone chronographed this? I'm anxious to see how much of a performance gain one can get over a 16" barrel. In my 94 Trapper, Remington 125 gr. SJHP's clocked in at an average of 2102 f.p.s., resulting in 1,227 ft. lbs. of energy. That's greater energy than a .223 Rem. out of a 16" barrel, with a bullet weighing more than twice as much. Using an average gain of 50 f.p.s. per inch, (compared to what I chronograped in a 3" barrel) one should achieve numbers of 2,500 f.p.s/1,736 ft. lbs. That's 200 ft. lbs. more than a 7.62x39mm. Awesome! But, at this point, it's only speculation.

Any responses will be greatly appreciated.

[nyresq]

I will assume the 3" barrel you used was a revolver. the pressure pushing the bullet out of the revolver will be less then a closed breech in something like a rifle as the gasses can expand out the rear of the barrel in the gap between the barrel and the cylinder. if you were to use a bolt action rifle or a Win 94 with a 3" barrel, the FPS would be higher then the revolver. as to how much higher I could not even guess, but just taking the difference in velocity of the two barrels and dividing it by the difference in length is not even close to an accurate measurement.

another factor to consider is powder burn speeds in long and short barrels. using a fast burning powder in a rifle will not get the highest velocity just the same as using a slow burning powder in a short barrel won't work either. for the longer barrel of a rifle, using a slow burning powder will generate higher velocities while keeping pressure in the safe range.

this is something a loading manual is good for.
look up the data for longer and shorter barrels with a loading manual, that will give you your answer.

[Preacherman]

Klingy, bear in mind that those bullets are not designed for that sort of velocity - not even close. You'll find that they often blow up on impact, with very little penetration indeed. To obtain adequate all-round bullet performance (i.e. penetration, expansion, etc.) go to a heavier bullet in the carbine - at least 145gr., as in the Winchester Silvertip, if not 158gr.

[GunGoBoom]

or 180 gr.