I have a Madbull Ultimate 6.01mm in my SVD and it's good. I dare say a PDI would be better, but since it would cost more than the gun and the Madbull TBB, I'll probably never know. The thing to bear in mind, as James said, is what do you need from it? I need to be able to hit man sized targets at 80m consistently - depending on wind conditions, I can, therefore the Madbull was a good buy. If I wanted to shoot 6" target bulls at 50m competitively, it'd have to go...
I have tried 2 TBB's in my AKS-74U, which is essentially a CQB weapon, but A. I like to have the option to use it for woodland and B. upping the FPS with a TBB could allow you to drop the spring power so the FPS remains the same but i) allows a higher ROF and ii) wears out the gearbox parts more slowly (although in actual fact I upped the spring to a 105 so that I got around 345 from one of the short barrels as opposed to 318 with the stock barrel & spring). The 1st one was a chromed brass 6.02mm and brilliant and the one in there now is a Systema 6.05mm which gives me less FPS and isn't any more accurate so it's going...
I put a PDI 6.01mm in my V61 Scorpion, which prima facie seems like a proper cock maneuver, until you realise that there are very few ways to up the FPS of an AEP and, like the above, I want to be able to use it in woodland, as a sniper backup. It is fucking excellent compared to the stock one, but that was JG so that's not exactly news...
You could do us all a favour and try a Lonex (from Helmetworld on fleabay) and tell us how good it is, b/c they are stainless steel, Lonex make perfectly ok other parts so we can be pretty sure it wont be shit, and nobody else seems to have a clue if they are actually any good...
edit: ninja'd me Ed, you cnut!
