Got these in yesterday, they are surprisingly small. I mean I knew where they were supposed to fit but the pics make them seem larger than they are...
Small, very well made. No fancy packaging just the unit, an allen wrench in a plastic zip top bag with a sticker saying Ajax Shock Transfer System, blah blah blah
CA M4 CQB Seal body, hop-up unit and gearbox. G&G outer barrel & those little gears on the hop up
Fitting in my CA required some effort. First off my hop unit needed some filing on the sides to get it to slide on. Also the top left corner of the STS needed to be filed down as well, due to the interior shape of the CA upper. Luckily the paint of the body and the anodized coating of the STS will show you where you need to trim, file, dremel. Since I had the files out I ran a small flat file along the front of the gearbox where it contacts the STS to be sure it had a flat mating surface and there were no casting marks or burrs hampering a solid fit
Next I couldn't get the unit to sit flush with the front of the upper receiver. Upon further inspection it was because the outer barrel I'm using is from a G&G and sticks into the CA body about 2mm past flush. being impatient I pulled the outer barrel out and employed my angel grinder to make this a quick fix. Got that all back together, loosened the set screws on the STS and got the upper and lower receivers to mate back up with the body pin being a real tight fit. looked inside the magwell as they instruct to tighten the set screws and found that hmmm, can't see the set screws because the CA lower actually hugs the hop unit, awesome. Pulled the pin to take it back apart. I did some fiddling and found that in my gun the pins on the STS are actually getting pushed all the way in and are actually not really serving a purpose as the unit itself is sandwiched in between the front of the gearbox and the body. I depressed the pins and tightened the set screws and reinstalled. again a nice tight fit of the body pin insured me that everything was good. plugged the battery up, maybe it was placebo but the gun sounded a bit more solid. I can feel more impact vibration on the RIS than I can on the lower receiver. Does that mean it's working? You know transferring the shock to the body and outer barrel? I'll say yes, that's exactly what it means...I guess, lol
King Arms M4
Next we installed one in BMC1979's King Arms. Fit on the Hop up without any filing at all, bastard! His KA is one of the versions that had the function bolt release that releases the little cover to shroud the hop up gears, yeah, that doesn't work anymore as he had to modify/disable/remove some piece of plastic to let the STS fit.
The KA magwell did not have the material around the hop up which was a good thing because he needed to access the set screws as the small brass pins on the STS did need to be extended a couple mm's to make contact with the receiver.
This can be installed in a few minutes as it was with the KA or in about an hour which I needed on my gun with the filing, grinding, fitting, etc . As for performance, my testing phase will begin this weekend at OP: Mountain Conflict and continue through out the winter playing season here in New England. All in all there will be 5 of us running these in different guns.
My findings will be based solely on the experiences with my gun.
CA M4 CQB Compact Seal turned to Mk18 MOD0, M120, ball bearing spring guide, ball bearing piston head, CA yellow piston, metal Cylinder head with sorbothane pad (custom cut, 1/8', durometer of 70), Stock CA gears, CA high torque, high speed motor, Systema shims, Intellect 9.6v 4200mah, deans. 370fps and 24.5 RPS on a chrono, not that PC audio analyzer software. Built by me, I've only listed the components that directly impact or house the moving parts