it seems I missed the part suggesting that the difference between firdge and AC compressors in terms of pressure is connected to refrigerant used...
there are fridge compressors using R22 I've seen them and I can buy them...
that they (AC compressors) could possibly pump twice as much as fridge compressors
I would say that there is no point in buying one if they
only pump twice as much as a fridge compressor
right now I am leaning towards using multiple fridge compressors (possibly R 22 ones) instead of building one AC compressor with higher flow... it seems that they are easier to build and to work with - maybe that's just my impression though... and apart from that a setup like this would have one great advantage - if one out of three breaks down you will still have two...
a setup with a considerable volume air reservoir
(BTW does anyone knows capacity of scuba tanks??) wouldn't need too many fridge compressors.. 3 or 4 would be IMO an overkill for most useres
(as it would be enough for 100 - 150cc guns semi auto guns and usefull even for large bore single shot guns - notice hwo much time does it usually take to load ammo etc. )
well, until someone builds an AC compressor that works 100% ok so that we could compare flow, max pressure, price and availability this discussion has to be a fully theoretical one...