I picked up an altaros booster (B2B edition) with the intent of running it into a regulator and shooting at 300bar or more. A bottle only lasts a few shots at those pressures... even my big 12L bottle isn't enough. It eventually worked out but it took a handful of modifications to the booster.
I found out pretty quickly that it was not intended to do what I wanted. The pump is controlled by a 5 port valve that toggles the pump back and forth. If there is air and electricity supplied, the valve will continue to toggle until it is disabled by the pressure switch. The problem is that the pump doesn't stop operating at the moment the switch activates... instead it will finish the final stroke of the pump and then stop. This causes the burst disk to blow if you hook up a regulator on the output. Of course it works fine if you use it as intended, by pumping from one bottle to another, but the a regulator will stop the flow in it's tracks even if the pump still has more to go before it stops.
I solved this by shutting down the driving air supply at the moment the set pressure is reached. This required an additional valve, a 3 port. First I tried a small 1/8 valve but the flow was too little and the pump wouldn't operate, hence the bulky 1/4" valve.
The original pressure switch also posed a problem. The hysterisis (difference between set and reset point) was huge, around 75bar. In order to operate my reg at 300bar I would have had 75 bar pressure swings on the input to the reg, from 325 to 400 bar. Too much... and the original switch didn't even go that high... so I shopped around and found a nice switch at automation direct. With independently adjustable set and reset points, and can operate at 12v it was perfect.
I wired this all up and used a power splitter to supply all of the electrnics from the usb-to-12v adapter cable. Fortunately the cable puts out just enough current to run all of the components from a usb power bank.
I made one more minor mod. It originally came with a piece of silicone tubing after the internal regulator (for dropping 300bar down to 120psi for operation of the pump). The tubing was there to burst like a fuse if the regulator were to fail. This tube had a very small bore causing a restriction, so I replaced it with a larger tube and installed an actual pressure relief valve.
This took about a month to put together... between shopping for different items, buying items with the wrong threads, finding unusual components etc. In the end it works flawlessly, and it's portable. I've got a small duffel bag on the way for easy transport to the range.
Side note.... fittings for this stuff is a major PAIN. China uses metric threads, everyone uses BSPT and BSPP sometimes, and the US uses NPT. Some use a face seal, some use a sealing washer, some use thread sealant, and nothing ever matches the fittings you have on hand. Major pain. Even best fittings only occasionally has what I need. In the end I got it all together but it took a few orders and 2 returns on amazon for mislabeled threads!
Will post a video next time I fire it up.