As I was reading this thread and looking at the photos I thought I should share with you my experience with chrony measurements etc.
I own a M1 Shooting Chrony for 3-4 years. A while ago I realized that my air guns had many ups and downs regarding velocity. The guns were not inconsistent but once I measured for example my CZ 200 consistent at 12 foot-pounds and the next weekend I got consistent 14 foot-pounds of energy. I started not to trust the measurements I was getting. I knew (many say so) that chrony measurements are affected by light conditions but how much? So I bought myself a second chronograph. This one is An Air Chrony MK3 and measures velocities regardless of light conditions. Now which one to trust? I had to make a comparison…
So I went back to my basement and put them side by side (the correct is in line) for testing. Conditions the same for both. Distance between them 20 cm. Air Chrony MK3 in front, M1 Shooting Chrony behind. Gun for the test CZ 200 S regulated approx. 14 foot-pounds.
Now the results...
Shooting chrony without any cover
Shooting chrony with cover
First test without any cover. The chronies exposed directly to light (not fluorescent)
I took 5 shots at about 875 fps (Air Chrony MK3). The average velocity measured by the Shooting Chrony was
47 fps higher, with the max difference climbing at 55 fps and the lowest at 37 fps. That’s a lot…
Second test with Shooting Chrony M1 covered with a plastic sheet and some white paper. It’s easier than using the shields and has the same results.
5 shots again, same velocity for Air Chrony MK3. The average velocity measured by the Shooting Chrony was
1,5 fps lower, with the max difference being 3 fps and the lowest 0,7 fps. That seems o.k.
My conclusion: A Shooting Crony should be in a shadow to produce reliable results. That again is
not a general rule just
my opinion from
my chrony.
So my advice from my own experience...
Glem, use the shields when you measure velocities with the Shooting Chrony just to compare the results you are getting.
Umair, your rifle shoots 25 grain JSB pellets at 950 fps. It should shoot the Heavies at around 850 fps (mine shoots the heavies approx. 100 fps slower than the 25 grain) That’s approx. 55 foot-pounds. You are reaching the upper limit. “
Weatherby”, who is the most experienced from us all, wrote: “I’ve modified quite a few and in general, around 56 FPE was the average obtained power.” So again, I think you are o.k. There aren’t many fps hidden, maybe just a few. Tune your rifle for accuracy and shot count and enjoy it. It’s a wonderful air gun. Mine is an ELITE 400 barreled to .25 and shoots the heavies at 790 fps. It’s one hole at 60 meters. Only modifications are a Huma regulator at 150 bar, transfer port drilled from 4,5 to 5 mm and valve seat opened with fine sand paper at aproxx. 4.5 mm. Hammer spring adjuster all the way out.
But again, that’s
my opinion.
Sorry for the long post.