G&G m4 blowback: lower was cracked so brought a echo1 lower and doesn't fit
 

Yes I brought a echo 1 lower and it looks like where the hopup is its not the same. If any one knows about this please help. I was thinking on cutting the lower on the echo1 so my hopup can slide through. will that work? Thanks for any help

If what I think is correct, you have a lower body that needs a two piece hopup. I believe cutting the excess part very carefully should work. At least that's what I've done in the past but I haven't work on a G&G M4 before.

Yeah this is what I was thinking as well. I cut down a TM M16A1 body to fit a 2 piece hop up unit. It was pretty simple since you can cut away pretty much everything at the front around where the hop up is down to the walls of the magwell. If you look at the body for a 2-piece unit, there is nothing in the magwell until you get back to the little ring area for the mag catch.

Echo 1 is based on the TM 2-piece hopup, where half of the hopup unit is attached to the lower receiver. It's not compatible.

There are ways you can mod in the receiver, including cutting that part out, but then you introduce a lot of instability in the lower receiver because that part of the lower hopup essentially braces the receiver. So it can be done, but I wouldn't reccommend it unless you like having a front end that you can wobble around like a wet noodle.

I would recommend just getting a fully metal body, or getting the proper 2 piece hopup.

Rite onn, thats what I was thinking, its better than going wit a two piece hopup..

TM 2-piece hopup is pretty cheap, like under $20 I believe. It's less work and you won't be fucking with the stability of your receiver.

You may still have the problem mating the G&G upper with the Echo 1 lower. Take the G&G upper (hopup and barrel out) and see if you can get the err wings (i don't know what they're called) into the back of the plastic body.

I don't think it'll work, Echo 1 copies TM's design and the upper is suppose to be held in place via rear tabs.

Yeah! your rite it gonna be trouble there may as well sell the lower I just brought LOL how f' in stupid