Chrono results with ROA

[Thatcher]

Just out of interest I chrono'd 6 shots with my Ruger Old Army earlier today - This is the 7.5 inch barrel and 30 grains of H777 by volume using a standard lead .457 ball.

What surprised me was it was averaging 1300 feet per second which is quite a bit higher than I expected.

I taped a target to the front of the chrono to stop the smoke cloud from triggering the sensors (get bizarre results without it) so I have to assume its fairly accurate in the reading.

Has anyone else chrono'd a similar setup, and what results did you see ?

 

[robert garner]

I had NO IDEA! 777 HEH?
WAIT.....WAIT....yes i c......wait ok 777 is in my future!
I have no idea what my roa's will think of this!
robert

 

[mykeal]

1300 fps sounds too high to me, but I haven't tested it in an ROA. I suppose it's possible. Do you have data for 30 gr of black powder in your gun?

 

[DMZ]

141 gr round ball @ 1300 fps from a 7 1/2" barrel would take a interior pressure > 36,000 psi. That would far exceed the ability of cylinder/nipple to contain it.

30 gr of fffg behind a 141 rb should yield ~790 fps.

Maybe the chrono measured unburned powder grains?

 

[mec]

Chronographs are a conundrum. I would not question or cast asperigas on anybody/s results from one of the things. This is what I got with .457 balls


35 Gr/Vol.H777 1046fps 89spread 340energy

 

[Thatcher]

I think what I'll do is try again with the chrono down at the target 25 yards away. This should hopefully remove some variables like smoke or particles still triggering the sensors ahead of the ball.

Though I think I'll chicken out and shoot from a rest as I'd rather not shoot the poor little chrony itself

 

[mec]

"...and shoot from a rest as I'd rather not shoot the poor little chrony itself ."

I hate when that happens. I polished one off myself a couple of weeks ago.