[LUTNIT]

But are you using a Deep Fire ver.2 piston? The first gen did have the cracking problem but the ver.2 is reinforced on the edges and I have had zero issues. I did have one of the ver.1 ones crack like you described.

The Modify pistons I have had die on me are not in experimental guns. One was in my ICS M4A1 when it was shooting 375fps and maybe 17 rounds/second, the second one was in I don't remember exactly which gun but it was a 325fps indoor gun with standard gears, motor, etc. that couldn't have been shooting more than 12 rounds/second. It just seems like I look at a Modify piston and it dies. I installed one in the second ICS M4A1 I had and it stripped without firing a shot. I pulled the trigger and there was a little pop sound and then gears free-spinning.

I dislike their gears because of those damn modular gear sets. They are so damn picky as to which guns they fit in. I tried using it in an ICS, JG, and TM mechbox and it wouldn't sit right in any of them (and I bought the one listed as for JG guns.) Their loose gear sets are okay but again, they don't use a standard diameter pin on the sector gear to draw back the tappet plate so you can't put on any standard sector gear clips to make feeding more reliable. Even at an average ROF I find that midcaps on the last 10ish rounds will misfeed, not so with a sector gear clip so I put them in all my guns now, not just high ROF setups. One interesting thing I had happen with a set of Modify gears was it rusted. Not after getting wet, not after sitting in a damp area for a week but inside a gun within 3 days. I have no idea what happened but I installed them brand new with a Modify piston using white lithium grease from Canadian Tire, piston stripped and a couple days later when I got around to fixing it the gears where brown with rust. Since they coated in rust it hasn't gotten any worse but I think its damn odd.

As for Modify being better than most I have to agree with some. The only SystemA parts I haven't had problems with are their gears, Prometheus cylinder heads aren't so great in my experience, but Guarder is great. I would use Guarder in everything if it wasn't for Modify being just as good (in everything but pistons), easier to get, and cheaper.

For pistons, hands down, no one can touch a Prometheus hard type. Seven steel teeth and reinforcements on both sides of the plastic teeth. Things are tanks, been running one in my sniper M14 for a season and last I checked it looked new still, at least a couple thousand rounds through it in the past year at 440fps with 12V battery for better trigger response in semi.

I have tested using .25's and .28's in all my guns and I find that .25's give a much better overall performance in guns under 375fps. You loose a little brush penetration but the amount of range you loose and how much harder it is to hit a moving target are really obvious. It seems the higher the fps, the less range you loose even as a percentage of the total range. So in say 390fps guns .28's don't have that much of a noticeable disadvantage in the areas of range and hitting a moving target compared to .25's. That is just what I have observed but I have only tested in my ICS CQBR and ICS are known for weird hopup reactions.

*EDIT*
I opened my AKS-74U a little while ago to downgrade it for someone who bought it. I had installed a Modify standard piston, stock STAR gears, TM EG700 motor, and 9.6V 2200mAh battery. Before downgrading it when it had exactly the same internals but a 390fps spring it had fired maybe 500rnds for testing, even after that few number of rounds the piston teeth have little dents in them, as said above a Prometheus hard type in my 440fps M14 after 2000-3000rnds still looks new once you remove the grease.