robbobsam Posted February 16, 2010 Report Share Posted February 16, 2010 To calculate the Ft/lb of an air rifle you do the following calculation. ft/lb = Velocity of pellet (feet per second) x Velocity of pellet (feet per second) x Weight Of Pellet (Grains) / 450240 eg, 712ft per second x 712ft per second x 10.6 grain pellet weight, divided by 450240 = 11.93ft/lb 712 x 712 x 10.6 / 450240 = 11.93ft/lb Simple !!! Quote Link to comment Share on other sites More sharing options...
mickmep Posted February 16, 2010 Report Share Posted February 16, 2010 or even easier................buy a combro for around £40. in my opinion a must have if you have a non fac air rifle. bought my rapid second hand and it was doing nearly 14 ft-lb when i checked it. probably not much chance of having it checked by police, but would hate to think what would have happened if it was while it was at illegal power. the fact that it was bought like it would be no excuse, and to be honest for 2 ft-lb not worth the risk. Quote Link to comment Share on other sites More sharing options...
mart46 Posted February 17, 2010 Report Share Posted February 17, 2010 or even easier................buy a combro for around £40. in my opinion a must have if you have a non fac air rifle. I can second this - had a new spring fitted in my hw97 by a shop and when I got it home, it was doing nearly 15lb-ft !! Did have words with the shop owner when I returned it!! Quote Link to comment Share on other sites More sharing options...
Al Downie Posted February 17, 2010 Report Share Posted February 17, 2010 Can you enter the pellet weight into a Combro??? I've had one for a few months and been measuring fps and then faffing about with my calculator! What a doofus. RTFM! Quote Link to comment Share on other sites More sharing options...
mickmep Posted February 17, 2010 Report Share Posted February 17, 2010 Can you enter the pellet weight into a Combro??? I've had one for a few months and been measuring fps and then faffing about with my calculator! What a doofus. RTFM! you can with the mk4, cant comment on the earlier ones. after you've shot through it you can read fps or ft-lb for the shot. if you have a mk4 you hold the top button (reset) for about 14 seconds and then can set pellet weight and a few other things. Quote Link to comment Share on other sites More sharing options...
SirFox Posted February 17, 2010 Report Share Posted February 17, 2010 Don't they make those small chronographs? Quote Link to comment Share on other sites More sharing options...
mickmep Posted February 17, 2010 Report Share Posted February 17, 2010 Don't they make those small chronographs? yep. small plastic ones you just fit to the ned of the barrel. not suitable for rimfire, but ok for fac air rifle. they are a great bit of kit, can buy direct from combro for £40. worth it for the peace of mind, knowing you air rifle is not generating illegal power, and knowing it is running near the legal limit, use mine regularly to keep an eye on the airgun. Quote Link to comment Share on other sites More sharing options...
Dekers Posted February 21, 2010 Report Share Posted February 21, 2010 you can with the mk4, cant comment on the earlier ones.after you've shot through it you can read fps or ft-lb for the shot. if you have a mk4 you hold the top button (reset) for about 14 seconds and then can set pellet weight and a few other things. My Crombo is about 10 years old and you can on that! Quote Link to comment Share on other sites More sharing options...
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