I lack the talent to reseal airguns and thus is very expensive if I buy a used airgun that needs resealing, I need a portable way to judge the velocity of a pellet and bb guns I am handling. Needs to be something I can safely do indoors. My chrono does not work indoors. Thinking of something that can be calibrated like ballistic putty but the only kind I found so far is not clear. Maybe a catalog that I calibrate the number of pages penetrated with my measured chrono readings for bbs and say wadcutter pellets but that is a lot of work. Anybody have some cheap and safe way (pawn shop will not let me test it if it appears unsafe) to test pellet and bb guns so I can at least tell if a reseal will not be needed. Would like it to shoot at least 75% of velocity of a new one. The last bb gun I bought, I put my hand on the barrel and fired it but it was Daisy 25 that I could safely look in the magazine to make sure it is empty. May not try it on gravity feed. I am looking for something east and more accurate than sound and feel of the discharge. I plan to visit more pawn shops in the future. Thanks in advance for all replies.