Chrony testing

What crhony are you using? 
I once did a series of tests where I shot through two chronographs by two different manufacturers simultaneously (pro chrono and red chrony alfa) and it was the classical 'a man with a watch knows the time, a man with two is never sure'. While chronies 'generally' agreed with each other, it was pretty clear to me that as measurement instruments, they, themselves had at least 5-7 fps random ES. Pro Chrono seemed to be a bit more stable though.
As a general rule of thumb, I would not expect a consumer grade chrony to have better than 1% precision (accuracy is less important to me).

This said, I foumd it to be important to keep the gun in exactly same position between shots and try to shoot a one hole group at the same time. This ensures that the pellets travel the same same route. 

I think what pulps is wondering is regulator consistency. Is that right? If so then yes its best to wait a few seconds between shots for the regulator to stabilize pressure between shots. What I do is waist the first couple shots when starting a session. Seems the reg need a couple shots to settle in at first. The first shot is usually not the same as the rest. That will tighten up your ES. Then just cock the gun slowly between shots. You can count to 5 or 10 or whatever you like as you work the action just do it the same every time. Consistency in everything aids accuracy. 

I'm using

http://www.pyramydair.com/s/a/Competition_Electronics_ProChrono_Digital_Chronograph/4015

Here is some interesting data for you.

This chart represents about 500+ pumps on a Benjamin 397, .177 cal. air rifle. Each fire is a 5 shot average, over a Crony Alpha. Although it agrees with most of the net's privately-published data, it doesn't come close to Crosman's published data: 10.5 grain, LUM77, at 799 FPS and 14.7 FPE! I think they exaggerate the real specs! 

What is more interesting is the data on the 21 grain pellets. I haven't thought through it yet, but I suspect it is a velocity, friction, inertia issues causing the data shown. 

The other thing that is not shown (I'm working on that now), is the grouping at 25 yards. Turns out, the Red Fire with 5 pumps is the most accurate of the bunch, with 1.2 inch groups at 25 yards. Assuming of course, I do my part! 

Enjoy.

​Pellet DescriptionNumber of PumpsPellet Weight Gr.FPSFPE Gamo Red Fire87.87219.01 Gamo Red Fire77.86978.42 Gamo Red Fire67.86647.64 Gamo Red Fire57.86236.72 Premier LUM77810.567210.53 Premier LUM77710.56439.64 Premier LUM77610.56088.62 Premier LUM77510.55757.71 H&N Sport8214489.36 H&N Sport72148811.11 H&N Sport62148611.02 H&N Sport5214338.74 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

That didn't come out right! It is the number of pumps (8,7,6 or 5 and one figure), the pellet weight (two figures), then the velocity (three figures), and the FPE (x.xx).

If I knew how to post a photos, that is what I would have done. If you want the chart, email me, and ask me for it by name.

[email protected]

Alan