I got my replacement Alpha Chrony. Went to the range to test out some snubs that I did trigger work on.
Model 642 1-7/8 barrel. My loads were 158gr lswc with 3.5 grs Bullseye and Wolf sp primers.

I did not record the whole strings as I was mainly testing for reliability of the gun. I also shot the same loads out of 2 other snubs.

They only averaged around 530 to 550 fps. This does not seem right to me??

Speer #14 says it should be 814 fps out of a 6" barrel.

Thanks

Would the FPS be that much less out of a 2" barrel??

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My loads with those components average 790fps out of a 6" barrel. Those do seem kind of low.

What most folks do to check their chronographs is get a box of 22LR where the velocity is known and posted on it and use that for reference. Might be a good thing to try.

The difference in my loads from my M686 6" to my M637 1 7/8" isn't that big. 791fps to 706fps (Average velocity).

Those do seem slow. It is possible that your Chrony is off. It is also possible that you have a slow lot of Bullseye. If you peruse enough dat you will note that top loads of Beye have varied from your 3.5 up to 5.0 in 38 special.....even from the same data source. Some of that is undoubtably due to differences in test barrels and ,some perhaps due to changes in max pressure specs (although the feared Speer #8 had 3.5 as max with 158 gr while Speer 10 had 4.2 as a standard pressure lead bullet load and 4.9 for max +P under a 158gr. jacketed bullet) I have come to suspect that lot to lot variation may be a bit greater than we have all imagined in canister powders and I am convinced that obtaining consistent presure data in relatively low pressure cartridges may be more difficult than most of us ever thought.

I agree the 530 to 550 fps isn't correct. 3.5 gr. Bullseye, Fed GM100M primer and a TVB 158gr LSWC out of my M642 w/ 1 7/8" barrel averaged 691 fps.

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Andy

Well I guess I need to calibrate my chrono against something known. Even using 22lr, is that out of rifle, a handgun or what? Think I will load some with HP 38 also and see what's up.

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Borrow a 6" .38/.357 from someone and run a few through the traps out of it. Although that FPS even out of a 1 7/8" don't sound Kosher?

You might want to re-crimp some of the existing rounds with a heavier crimp. Also, mike some of the bullets to see if they are undersized.

If the chrono doesn't have a way to adjust it, how do you figure the correction? By figuring the percentage error when comparing a known .22 LR velocity or by adjusting for the difference in FPS?
Ed

I can shoot some out of my 686 but it is 4". As to crimp, they are about as heavy as they can be, I ran them all through a Lee factory crimp. I will also try loading some Gold Dots and Xtps and see what I get.

I think I liked it better without a Chronograph. No news is good news if it went bang and was accurate All was well.

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I have a Chrony Beta and I have had a dickens of a time getting reliable FPS readings. First I changed the battery, then I monkeyed with the screens and then Chrony tech support said I had to make sure the sun was in the right position. Finally put it away. Lots of times I would get readings that were half to a third of what I knew the velocity should have been. I seriously doubt there's a problem with your powder.