.62 Chronograph Results

[AK in PA]

Yesterday, I chronographed my .62 fusil for the first time. The results are "interesting". All loads were 70 grns of 3f Goex.

0.695 "hard" lead ball (622 grns) and 0.015 pre-lubed patch, swabbed barrel = 1,044 and 988 fps

0.595 pure lead ball (604 grns) & 0.015 pre-lubed patch, fouled barrel = 702 and 725 fps

0.595 pure lead ball (604 grns) & 0.018 patch w/ Lube 103, fouled barrel = 713 and 1,205 fps

Granted, this is very limited testing, but two glaring observations appear:

1) Consistency was poor. (Note low 700's to 1,205 fps with the 0.595 ball.)
2) The heavier ball generally showed a higher muzzle velocity than the lighter ball, which seems counterintuitive.

Two thoughts come to mind for these seemlingly odd results:

1) The larger (heavier) ball/patch was seated in a cleaner, swabbed barrel. (It will not fit down a fouled barrel.) Perhaps there is less gas escape on around a ball in a clean barrel, which provides a higher pressure and velocity than with the smaller, lighter ball in a fouled barrel.
2) Testing was done with the muzzle just inches in front of the chronograph. Any muzzle blast coming out ahead of the ball may have had a significant on the readings, and if so, would invalidate them completely. (I've seen this flame-ahead-of-ball in slow-mo videos.)

It will be interesting to repeat this test with the chronograph set up perhaps 10' ahead of the muzzle to avoid potential issues with muzzle blast. Has anyone else chronographed their flinters and gotten odd results?

 

[nkbj]

When I had a chrono in the eighties I could get odd results from being to close to the muzzle blast off of anything.

 

[nkbj]

OK. Couldn't stand it any more and ordered a new one. Will post results when can.

 

[David Grout]

You are way to close to the first screen. You are getting blast and smoke going over the screen and triggering it. You should be at least 6 to 10 feet away.

 

[deadahead]

Good morning- Hopefully you meant .595 hardball not .695. I think you would need to take as many variables out of this test possible. Have your different test subject ( lead orbs) separated, but tested with same patch thickness, same powder load, same lube, same loading and swabbing procedure, and etc then do the test with different lead types of lead balls from clean to fouled barrel. This might give you relevant data in which to validate your assumptions. I think you should move your chrono farther down field to avoid gases, unburnt powder, and patch material from affecting chrono readings.

 

[GreyWhiskers]

I think I put my screens a full 7 yards in front of the gun when I was testing. GW

 

[Deadeye]

Yep, you need to be about 7 yds. or more to get correct readings. What's the (600 + grns.)A .595
pure lead ball should weigh about 317 grains.
Deadeye

 

[AK in PA]

Thanks, Sounds like my hot gas guess is probably right. That only dawned on me after I got home. I'll need to scrap these numbers and run another trial standing further back. Should leave the face of the chrono covered in good black soot! :haha: And yes, I meant 0.605 ball, not 0.695. And grains are in the 300's. I typed faster than I could think.

 

[hanshi]

Thanks for sharing but your particulars are confusing. A .62 can take a .595" ball but not a .69" + or -. The weights you quote are not realistic. A .595" pure lead ball (the heaviest material) would weight around 330 to 335 grains and not 600 plus grains.

I agree your screens should be set no closer to the muzzle than 15' to 20'. You should fire a minimum of 5 shots each load and change only ONE variable with each group. Do that and your results will be much more meaningful. In fact, you've inspired me to to test WW ball vs pure lead ball. Better luck on your next test.

 

[trent/OH]

I'll need to scrap these numbers and run another trial standing further back.

If at all possible, don't shoot through your chronograph from a standing position. Murphy, of Murphy's Law fame, loves to find shooters using a crony while standing. Really embarrassing things will happen if you try it long enough. Shoot from a bench or rested position, and remember you aren't shooting for group size through the device, just shooting through the device (and thus not shooting INTO the device).

Many here, myself included, are looking forward to your results.

 

[Loyalist Dave]

One of the fellows at my neighborhood range puts up cardboard in front and behind where he will position his chronograph. Then he puts a target on the front piece of cardboard, fires a couple of rounds from a bench in a sandbag postion, and uses the grouped holes to position his chronograph. That way he assures he doesn't get anything other than the bullet passing by, even though he places the chrono at 7 yards. He's a stickler for details, but he says gets good data that way.

LD

 

[tenngun]

I shot a doe at about 30 yards with my .62center mark tulle.It was a quarting shot and tween the center and top of the shoulder .It passed through the top of her l lung through her pulmanary artery lower right lung right side of liver and exited. She turned and ran stright from me about 20 yards stumbled fell got to her feet and staggered 10 feet or so and fell.I reloaded and waited for 1/2 an hour or so(2 or 3 min) and she was dead when I walked up to her. I love to look at those numbers, I have a copy of lymans blakpowder handbook and spend some time every year or so looking at those charts.A 100 foot pounds from an arrow kills but I dont think any of us would try to shoot a deer with a .36 that has 300 fpunds.I like lots of lead but I just never figgured out what all those numbers mean.I do know that my 50,54 and 62 can throw a ball through over 3feet of meat and flesh and has put deer elk and antilope in the skillet :surrender: