Excellent work Mubhaur ,- How many shots do you speculate could be obtained with your current set-up, without the additional plenum?This would seem to be MY logical path, since I have the Air Force LRT stock ... which doesn't allow Your modified plenum.
A 16 gr. CO2 cartridge adds about 20 cc to the volume.... I used one for a reservoir on my .25 cal Disco Pumper Carbine.... Reply #45....https://www.gatewaytoairguns.org/GTA/index.php?topic=37401.45Detail photo above from Reply #16.... They are threaded 3/8"-24NF.... and you can drill the neck out (to at least 3/16") for more airflow to use as a plenum.... They actually have an insert pressed in, I drilled it out until the insert spun out, but I can't remember the drill size.... The drawing I got with my 16 gr. cartridges said the burst pressure is 500 bar, but CO2 vessels are normally rated at 1800 psi.... That would indicate a safety margin of 4:1.... A minimum of 3.5:1 is used by ASME for all pressure vessels.... That would work out to 2070 psi, with a 3.5:1 safety margin.... You should be fine at 145 bar.... Bob
Your calculated efficiency is pretty spectacular.... However, if you are shooting below the setpoint of the regulator, then you must include the volume of the plenum in the total available air volume for shots below the setpoint (all shots below 145 bar).... That will lower the actual efficiency somewhat.... Nice job!....Bob
Quote from: rsterne on January 18, 2022, 02:14:12 PMA 16 gr. CO2 cartridge adds about 20 cc to the volume.... I used one for a reservoir on my .25 cal Disco Pumper Carbine.... Reply #45....https://www.gatewaytoairguns.org/GTA/index.php?topic=37401.45Detail photo above from Reply #16.... They are threaded 3/8"-24NF.... and you can drill the neck out (to at least 3/16") for more airflow to use as a plenum.... They actually have an insert pressed in, I drilled it out until the insert spun out, but I can't remember the drill size.... The drawing I got with my 16 gr. cartridges said the burst pressure is 500 bar, but CO2 vessels are normally rated at 1800 psi.... That would indicate a safety margin of 4:1.... A minimum of 3.5:1 is used by ASME for all pressure vessels.... That would work out to 2070 psi, with a 3.5:1 safety margin.... You should be fine at 145 bar.... Bob Hey Mubhaur,Thinking of adding a 16 gram co2 cartridge / brass extension to the bottom blanking plug of one of the RAW's. If I can increase plenum size by 20+ cc's for less than $10 and some elbow grease - that would be great . The cylinder can be conveniently fitted in the stock between the Bottle and M-Lok rail.
Yes, it's "flying by the seat of your pants" -> functional. Like the professor on Gilligan's Island, Bob can make anything out of two coconuts and bailing wire .The problems I foresee are the lack of robustness/fragility/leaking and increased difficulty working on the regulator.The positives are: It's under the hood .