Let's see: For a back of the envelop approximation, let's make these observations:
The S&W revolver with an 8.375" barrel has a published muzzle velocity of 2200 FPS with a 200 gr FTX bullet. Federal Fusion MV is 1600 FPS with a 260 gr bullet. Lyman Universal Receiver data with my handload in a 10" barrel for 240 gr bullet is 2300 FPS. Interestingly, the T/C Encore data for a 15" barrel is virtually identical to the revolver data (they let you have about 0.5 gr at the MAX) and about the same velocity for my handload (about 2300-2400 FPS).
While YMMV for increases in velocity with barrel length (and even among seemingly identical barrels for the same receiver and cartridge), given the Lyman data and the basically flat velocity vs charge weight curve for H110 in this cartridge, I am inclined to think that an increase in barrel length of 5" is going to buy you much, if any, increase in velocity. That is, I expect that the MV will be about 2400 FPS.
This, I hope, explains the genesis of my question. Why is this curve so flat? Is it because H110 is so fast that it does almost all its work in the first several inches of barrel. (BTW, a similar insensitivity to barrel length is claimed by Hornady for its Superformance ammo).
And then there is this video of one with a 24" barrel. I feel better knowing that I am not alone in fracturing a foreend.
