So awhile back I rebuilt my main m4 after the src gearbox shell rails that support the piston wore a bit thin from years of use. So I bought a retro arms split shell. It appears the bushing holes for the bevel are off spec from the motor entry angle. Causing very poor pinion to bevel meshing, and costly damage. Been trying to figure out why I have blew my motor bearings (first time that's ever happened) and blew out a couple pinions. Tried testing with a 3d printed motor angle checker but the gearbox clamps down on it so hard that it straightens out while bending the part that goes in the bushing holes resulting on a false positive angle check, yay... I checked some photos of their other v2 shells and apparently this is a problem with all their shells. My guess is the bushing hole is off by about .3mm forward orr they could have the bottom of the gearbox off causing the bushing hole to be too far forward. Who knows, they would have to check the schematic to what actually comes out of the cnc machine. All the bushing holes could be forward together for all I know. Basically when I shim I leave about .1mm to .2mm room between the pinion and bevel for meshing, even with that room the bevel is tightly jammed and doesn't wiggle at all, which it should a hair. Even if I let the motor height way down it still stays too tight,, since the pinion is trying to mesh at a bad angle. It's 100% not the grip. A pinion tooth is about 1.20mm wide, so being off by .3mm is enough to cause some some wear or failure. I typically don't complain about issues like this, but this shell was not cheap and when I buy a cnced part I expect it to be usable, not blow out my motor tower bearings and two pinions in less than 6k rounds. Hopefully this issue doesn't go ignored, I contacted them about the issue, but they have ignored me in the past. This issue also will cause absurdly high amp readings. I'll probably switch to a lonex shell. I used to have a src shell and ran about 140k rounds on the same pinion without all this weird drama. I bought the shell off brillarmory.com but this clearly isn't his fault. This issue really has torn up my seigetek bevel which isn't cheap to replace. I could try to return it to him but that would likely hurt his pocket in the end. My bevel looks worse than it does in this photo now, that's another 50 bucks down the drain, the gearset isn't from brill. I would assume some would think I'm ocd, but when parts that never blew out start blowing out... I use a small hole in the shell to adjust motor height and shim the bevel up to the pinion then back off. I had the motor tightly clamped into the shell to set the bevel height with the motor 100% in line with the shell, a method that has worked for over a dozen high speed builds I've done over the years with no issue at all. I also make sure my motor tower is snug in the gearbox, no slack or any room for error. So thoughts? Am I going crazy or is this really what's going on? I can't even run 3k rounds without damage. The bushings are retro arms 8mm installed with their tool with support on the backside of the bushing holes to prevent warping. Oh and if anyone has a couple shells that work with g&p receivers for sale pm me. Lonex shells are sold out basically everywhere.