problem with installing hop up unit
 

hi i own full metal AGM HK 416 and it had 2 piece plastic hop up unit. so i decide to change it to one piece metal hop up unit and bought systema one piece hop up from one of ASC member. When I got the package it was fine, there was no problem with hop up what so ever. however, when i tried to put the hop up into my rifle, it's too tall. In another word there is little gap between top and bottom receiver and I can't lock it with body pin. so far i tried to trim down where hop up unit sits, but there is still little bit of gap left and i really can't trim down anymore. what should i do here??? should i also trim down my hop up as well ??? any thoughts??
thanks

Pictures might help.

here i hope that this would be better

Attachment 13537
here is the gap
Attachment 13538
this is the part the i trim down. I think by 2mm or so
Attachment 13539
here is another angle of gap
Attachment 13540
and this is the hop up.

you need to trim a fair amount. look inside and see where it's still getting hung up.

I put the one piece metal hopup in my marui receiver and I had to cut more than expected.

I've never installed a one piece hopup in this type of setup but I was under the impression that you had to totally cut out that section iggim trimmed?

I thought so too...the last one I did needed the opening flush up to the front of the magwell...the "base plate" of the hopup unit is usually square...and it decends down far enough to be where the the built in base plate is on existing receiver.

It's not only got to go in/down far enough...it's got to be able to be "tilted" in as the receiver closes up.

you're right. I kept cutting until it looked like there was nothing left. test fitted and cut some more. seeing as the one piece unit doesn't require a mounting point, it will look like a 'huge' void.

Inside the receiver needs to be squared off, and a small chunk need to come out from the front of it so there's enough room for it to slide backwards and forwards.

I did this on my old Marui body. Completely cut out that whole section. And it worked like a charm. It is completely empty in a metal body.. Why would it be any different if it were a plastic body.

that silvery bit you see needs to disappear.

Yes, the front section needs to come out, so the upper receiver with one piece hopup installed can slide back onto the lower receiver. Cut out the part that would impede that on the top/front of the lower receiver. I can give you more details if you need it.

no actually i got em fixed. what i did was trim down that square part of hop up by 1 mm and i was able to remove the gap.
thank you every one