FPS loss 3" vs. 2" bbl

[Ben Cartwright]

As the title states what is the common loss say on a sp101 going from 3 1/16 to 2 1/4 i have heard 50 fps to 100fps per inch of bbl are there any ballistic proof to this?

[Laz]

I think it is very dependent on the ammo and the particular gun, although I generally use the 50 fps figure for a ballpark estimate. Obviously, there would generally be some loss/gain. There have been many published chronograph results in print and online that show a general pattern (with a lot of variation between published reports).

[Ben Cartwright]

Good point so generally a ruger might shoot faster with the same bbl length and same ammo than a smith and vice versa?

[Sarge]

Each gun is a law unto itself. Unique characteristics like individual chamber dimensions, barrel-to-cylinder gap, and the smoothness/land-groove diameter of the barrel can all play a role in the actual velocity rendered by an individual revolver.

On the original topic however, here are some results I got with a 2 1/8" SP101 just a few days ago:

Some chrono results, Ruger SP101, .357 2 1/8” barrel. 062607. 79 degrees, partly cloudy and muggy. Shooting was about 7:45 PM with no groups fired; just peeking at the ‘speedometer today. Five rounds fired, 5 feet from the Chrony Beta Master, unless otherwise indicated. SD & ES were ignored given the platform.


CCI Blazer 148gr HBWC .38-S, 642 fps

Fiocchi 148gr JHP .357-M, 1090 fps

CCI 125gr JHP .357-M, 1303 for 4-1 error

Federal 125gr JHP .357-M, 1295 fps

I can't say on the 3" SP101, as I've never chrono'ed one- but given the application I wouldn't worry about the shorter barrel 'pulling the load'. Even the 'slow' Fiocchi load expanded nicely to .580 and just penetrated three, water-filled gallon jugs at 15 feet. The .38 HBWC at 642 also penetrated all three jugs, and even went about 5/8 deep in the old catalog behind them. It didn't expand but being a little lead cookie-cutter, it probably don't need to.

They short SP's will shoot too, with ammo they like:

http://i186.photobucket.com/albums/x187/SargeMO/SPat25w38HBWC.jpg