Gonz.

@RogerborgThanks for the recommendation. If ak2m4 has some ZCI barrels coming in, I may just wait for one of those. @ak2m4 Thanks for the heads up. I'm after a 229mm barrel. @Fatboy40 I didn't think such a small increase in barrel length would make a noticeable difference, so I appreciate the warning. I can wait a month for more stock to arrive, but it's useful information to have on the forum. Makes me wonder what fps I'll get if I stick the 363mm barrel from the Nuprol in it ?

That's great info, thanks. Thanks for confirming your experience is the same. I'm glad it's not just me. So I guess I could go with it as is or maybe enlarge the cutout in the stock barrel. I'm also open to swapping out the barrel and if ak2m4 is due some more stock of ZCI barrels, that might be my preferred option. I have been contemplating getting a 247mm ZCI barrel as it's in stock and the flash hider has enough space to hide the extra length. Otherwise, the gun seems to shoot well. Mine is just curving BB's to the left a bit, which is why I ordered the rubbers. FPS on 0.20's is right around 346 fps average and 7.4v lipo is plenty. Ah, perfect info thanks. I will measure the bridge on the Nuprol tonight.

Thanks for responding. I haven't tested it because I can see the contact area of the rubber does not clear the cutout in the barrel. The Macaron contact area has a triangle shape and it's the base of the triangle that is catching. Consequently it's only the point of the triangle that is pushing down through the cutout and that won't be able to provide a consistent hop. I have 2 new Macaron 60 deg rubbers and both are the same. This is what they look like, which apart from the untidy edge on the inside, seem to be fairly consistent with stock images like the one below. Thanks for the info on having to trim the rubber lips with the ZCI barrel. If you still have the original barrel, would you be able to measure the thin bit of barrel between the cutout and the end?

I've got an M904G and seen some of you mention putting maple leaf macaron hop rubbers on the standard barrel, but mine doesn't seem to fit properly. The protruding part on the inside of the rubber doesn't quite fit the cutout in the barrel. When I push the rubber down through the cutout, the wider end of the protrusion catches on the thin piece of barrel between the cutout and the end of the barrel. If I stretch the rubber on to the barrel a bit more it works fine, but the rubber won't stay there on its own. I've measured the thin section of barrel between the cutout and the end at 2mm and I think the clearance between the rubber inner protrusion and the end of the rubber (on the inside) is about 1.5mm. The rubbers are from @ak2m4 so are genuine. Does anyone know whether the rubbers are out of tolerance or is 2mm of barrel section more than normal? I'm also interested to know if the ZCI barrel has a thinner section between cutout and end. Would appreciate any pointers. Airsoft Dad.

Welcome Tony. I can't help you with clothing, but hopefully someone else can give you some pointers.