Does anyone have any data on the velocity loss caused by the air gap between the cylinder and forcing cone on a revolver?

My SRH 9.5 has less than .002 gap.

I don't have access to a chronograph.

I don't think it makes that much difference to the intendee, but I'd like to know.

Thanks

I haven't directly compared myself, but I'm pulling from information in Hornady's 5th edition reloading manual. You can gain 250-300fps when comparing an 8" revolver to a 10" Contender. I realize that the extra barrel length will help a bit...so the difference may be more like 200-250fps. That's just a semi-educated guess, maybe somebody else has a better idea.

John Linebaugh said at the Seminar that with a .002 barrel cylinder gap you only loose about 20 fps compared to a pressure barrel.

Thanks Sean,
I knew someone out there had some information.
I just discovered that Accurate Arms loading manuals list data by guns fired. In other words the .44 Mag data for A5, A7,and A9 is all from a 7.5 inch Redhawk. Makes it a lot easier to make a load decision when you don't have a chronograph.

You know I consider my chrono one of my most important load development tools. Tells me when I am getting into dangerous territory because you really want to be reasonably close to the powder/velocity ratios listed in the manuals. Plus on firearms like my Encore I can figure out trajectory for sighting in. Midway has them on sale about twice a year, that's where I got my Pact. Slim

Old Jim, The Speer manual also has the velocity from an actual gun instead of an unvented pressure barrel.

Thanks again, Sean.
I'll look that up.

Have you ever tried A # 7 in a 44 mag?

I had some left over from a 45 ACP venture. Tried 15.5 grs behind a 240gr Wheel Weight bullet. Very quiet. Very pleasant. According to the book about 1400 out of a 9.5 SRH.
I've been shooting 9 gr of Unique for a practice load at a swinging 3/8" steel plate. The A#7 makes a much more definite impact. Dents are about 1/8 deeper. Looks real interesting for a mild feeling hunting load.