It's been mentioned somewhere before but with the clamped one, you get higher velocities shooting a few inches away from the chrony ; barrel unclamped, of course. Can't fancy why.
Ready to laugh ? I've just joined a famous club...Went outside this afternoon and began checking my airguns' speed consistency. Amazing with a Crosman Vantage NP (.177) with 4 shots at 266 m/s and 2 at 265. Tried with my Beeman P17 and found unpleasant dispersion (111, 113, 109 , 102)... now it's time to do something. Checked the faithful Crosman 2100 at 4 pumps : 153, 150, 150, 150. Ok, now let's try the Webley Rebel clone, 4 pumps too : 157m/s, 154...and nothing to read but hey, that shot was a bit noisy. So I kept shooting 4 other pellets, NO MORE RESULTS, not even the famous "err". But isn't here something missing in the "speedometer" ?... WHOAAA!!! I just ordered a new one.
lol Well, I'm in good company then. Mine still works fine, though. Miracle considering the BB actually hit the IR emitter hard enough to do what's shown below...
Bullet energy calculator:The formula is E = (M x V²) ÷ 450,435The energy of an 8.44 grain pellet at 900 fps = 8.44 x 900 x 900 / 450,435 = 15.2 foot poundsThe energy of a 7.33 grain pellet at 496 fps = 7.33 x 496 x 496 / 450,435 = 4.0 foot pounds
The formula I use in my spreadsheet is: Energy = (Average Feet Per Second)2 X (Pellet Weight in Grams )/ 450240, so I believe Td is correct with the 450,240 divisor.=(M4)^2*(G4)/450240 in the spreadsheet...
ordered the amazon unit feb 24 got here today... it works.. My BSA Buc .22 is tossing the 30g BBT at 30 fpe JSB 18.1g at 29... factory stock... need to see if spring preload can be turned up or if it already is...