Chronograph Test

Joe Friedrich

Joe Friedrich

Member
The pellets I'm using are shooting 18-20fps under the 20fpe, the PVM-21 was used for testing. The Chrony was placed 12" from muzzle.
The barrel was cleaned before the test, but I do use a bore conditioner for the last patch. The bottle was filled to 3000psi and kept as close as possible to that fill.

First up was the 21.14 H&N pellets, 5 shots leaving the power setting the same Results: 1) 610.8, 2) 615.2, 3) 609.3, 4) 612.1, 5) 612.6, as you can see it wasn't close to the 652.5 mark. I cranked the power up, it was tuned to where it was shooting an average of 646 fps. Below are the results from this setting.

JSB-RS-13.3 5 shots unlubed, 12" from muzzle
1)838.2
2)836.5
3)832.6
4)832.4
5)834.8

JSB-15.9 5 shots unlubed, 12" from muzzle
1)763.2
2)763.6
3)764.8
4)762.1
5)762.6

Then tested the JSB's 15.9 at 3" from muzzle 5 shots. I didn't feel the need to test the other pellets after seeing these numbers.
1)762.5
2)762.2
3)759.8
4)761.9
5)761.8

Next, moved Chrony 8' from muzzle, here's the interesting part.
H&N 21.14 grain
1)638.8
2)636.4
3)635.2
4)634.6
5)631.8

JSB-15.9 grain
1)758.6
2)758.4
3)758.5
4)757.5
5)757.4

JSB-RS-13.3 grain
1)834.6
2)840.1
3)841.7
4)832.8
5)832.6

I know each rifle will present different numbers, it was fun and interesting to see not much change in distance values, but a significant difference from where the rifle was set to where it had to go to get to that 652.5 fps.

Regards,
Joe
 
Last edited:
Joe,

From the results you just posted I'd think you'd go with the JSB 15.9's and set everything to comply from there. Man, are those babies consistent!

Dave
 
Dave,

I agree, the CP's were even better. This is the most consistent my rifle has shot after turning the power up for that 652 mark, although it was only 5 shots. Shooting either the CP's, JSB's, or JSB- RS's the rifle will no longer be sub 20 fpe which is fine by me, since this is there guide lines but I already knew this and the test just confirmed it.

Regards,
Joe
 
Joe,

Looking at the difference in velocity between 12" ad 8', I think something strange was going on. Likely settling the spring after the adjustment or something since the 13.3gr numbers seem too high at the 8' mark.

But anyhow, yes, I feel using the "standard pellet" can make it much easier on the match officials to check guns ... since there is only one average velocity number for each caliber in a given class to look for. The fact it can give us some welcome "wiggle-room" in velocity setting, is a side benefit, and I don't feel we should discourage this situation needlessly.
 
Joe,
I think everyone enjoyed the wiggle-room on the velocity Sat. at Pinnacle Mountain.

After finding out the change was made a year ago. Just updating their website with the change in the rules would have been helpful.

Paul
 
usa guys learn fast... no need for rules too far in advance... he hehe
interesting.
dk
 
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