I have a black eagle M6 that I got (same rifle, cheaper, no bipod), but only for small field play - in no way are these kind of "sniper rifles" going to work in any long range, sniper type roles...
but the first day I got mine, I did open up the bolt and do some playing. The short: its not easy, and you'll most likely ruin the gun.
the good: you can build a whole NEW bolt - I suggest acquiring a new sprign first, I think either an APS 2 or VSR-10 spring will work OK. But not 100% sure yet - I DO know that anything with a decent level of power WILL break the sears in the rifle!
The other good news: jb weld and 3/4" copper pipe are all you need to make a new bolt, just reuse the piston/spring/spring guide/nozzle/bolt handle. The 3/4" copper pipe is the same size as the stock bolt, and actually fits better. Its almost as thick, and quiets the gun a bit.
I added a 1" spacer to the spring in my rifle, and it helps, but the gun is still probably only shooting 300 fps - not useful as a sniper AT ALL. But when you only have a couple guys for a backyard game, it makes for an interesting scenerio - now when I get it to shoot 450+, I'll be happy, but by then I'll probably have made my own steel sears and spring guide holder - and probably a whole new custom bolt with new nozzle, tightbore AEG barrel and some other 'mods' I plan on...