First rifle build.

I have built an SR25 using HPA airstock. I’ll share what I did, and you can decide if this will fit your budget/needs. I took a Boneyard SR25 and parted it together. There was some dremeling and and filing. I put a Polarstar Kythera for the V2L mech box in it, and I use an Umbrella Armory R-hopped barrel w/ UA’s Maxx hopup(they sell it with an Rhop specific arm, but the drawback is bbs need to be ≥.30 grams). THe air source comes from the P* UGS regulator stock for TM style receivers. The setup shoots very well, but it is definitely not a cheap setup. I was lucky to find a boneyard donar for cheap(les than the cost of an outer barrel, hand guard, and mech box). It came with a mech box(quality is not as important on an HPA build here, as long as it’s straight). The barrel and sights were good, but the reciever was in four pieces and plastic.(Upper reciever was 2 plastic peices held together by the rail). I picked up the Matrix aluminum reciever set on sale for ≈$40 to replace it. That was the cheap parts.

The benefits of this build are FPS versatility and noise signature being very low. As it is very quiet, and the regulator adjusts the fps by a set screw on the ‘buffer tube’. I can run this setup from 250 fps to 550 fps without taking anything apart. Two other benefits I found are the trigger on the Kythera is more realistic than other HPA/AEG triggers, and there are absolutely no electronics on the gun.

The drawbacks are the price, and limiting source for air. I overcame the air source issue by purchasing a home filling station. Those have gone up in price since I purchased mine. The outdoor field I play at does sell air fills for ≈$10 day pass, since their main source of income is their paintball players. Some others have purchased scuba tanks, and go to dive shops and use a fill adaptor on the scuba tank to fill their other tanks. But that is another issue with the HPA world.

More economical approach would be to do an AEG build. I don’t know much about the aeg gearbox builds, but with what the guys on here talk about, they can perform just as well(some say better) than an HPA setup. With quick change spring setups on gearboxes now a days, you can swap out the springs with minimal disassembly. You will still have to remove the ‘buffer tube‘, but if you have built up your own Gearbox, this is a very little thing. Either setups, always start with a high quality(not necessarily tightbore) barrel with good hopup packing and nub.


So help us a little more here, what’s your budget to do this build?