Range day chrono readings

[blackd24]

I wanted to get velocities on my 41 mag reloads. I thought this information may be helpful for others and I’m also open to feedback to my questions. I first checked my 9mm target reloads - consistently around 1000fps so the chrono seems to be working fine.

All 41 mag are shot out of 6 inch new production model 57-6. Chrono was about 10 feet in front of me. Starline cases, federal large pistol primer for hp-38 and 2400, cci lpm for the H110. 1.585 OAL for xtp bullets. 1.6 for MBC bullet.

6.6 grains Hp-38 with the 225 grain MBC “outlaw” bullet. Consistently 850 fps which is what I expected and the general purpose of this round - closer to special than magnum.

17.5 grains (max of 17.8) of 2400 under the xtp. Consistently at 1150 fps which is about what I expected.

21 grains of H110 (max is 21.5 or 22 in most sources that I’ve seen. Consistently 1250 fps. Online data shows a test barrel of 10 inches and then obviously another .5 grain, but velo over 1400 fps.

Am I way off with the H110, or is that a reasonable expectation of velocity? I had a heavy crimp, checked halfway through one cylinder and the bullets didn’t move. Was the chrono too far away? 10 feet

Thanks for reading!

 

[Larry in wyoming]

They don't have a barrel to cylinder gap. You do. That 4 extra inches of barrel helped them some as well. 60 to 100fps? Powder lot?

 

[eddiememphis]

How did they group?

 

[blackd24]

H110 was a good group, probably 3 inch spread at 15 yards, 9 o’clock. The hp38 grouped about the same.

 

[PO2Hammer]

Chances are they are using a test barrel with a tight chamber and no cylinder gap, tough to compete with.

 

[lordpaxman]

Was the chrono too far away? 10 feet

What kind of Chrono, and what do the instructions say? That’s usually the minimum distance you want so muzzle blast won’t affect the readings for a shoot through Chrono.

I don‘t have a 41 mag, but my revolver readings are pretty typically under book values. You’ll also get some differences with powder forward or powder back.
I would say your Chrono is reading ok. I like to shoot a known value at the beginning of a Chrono session to make sure it’s behaving. I use a box of factory blazer 9mm or CCI SV .22LR.