fitting trigger housing question

[roland3]

Im fittting the trigger housing to the reciever and the trigger cage wont allow the housing to fully seat in the up position. It lools like stock needs to come off the cage or the reciever. where is the best place to remove the stock from. the housing is about .08" from going home in the up position. Im thinking that I should remove stock the the slots on the bottom of the cage, where it sits on the tabs in the housing. that way all the other relationships will stay the same.

[texlurch]

Where are you measuring from for "up"? Are you using the CETME or the G3 trigger pack? Remove the pack and just put the grip housing on, does it fit any better?

[texlurch]

Is this the area you are referring to? It doesn't have to go flush with the curve on the receiver, as long as the stock pin holes are lined up, and the ejector is riding high enough on the bolt.

Ideally you want the lines to be close and parallel.

The grip housing should overlap the sides of the receiver, the pack should butt tight against the bottom.

[rustypirate]

If you are using a cast receiver, I have found that all of the ones I have built needed to be filed on the outside of the receiver along the sides of where the lower grip frame mates to the receiver to work. They were all a little bowed out in this area. I have also needed to file down a little on the nubbs sticking down into this area as well.

[Perro]

special weapons used to machine the receiver on these if you got a cast

they are cast, so they are larger/thicker than a mil spec stamped and its finish machined before sending it out - unfortunately century doesnt take the time to do that stuff to there guns.

mill the bottom of the cast receiver cause it is the part out of spec, not the fire control box

[roland3]

so your saying that they did mill them but not to the correct dimensions? so I will set up and take more off the bottom of the reciever where they milled it already. thanks for the input because I was going to assume they milled it to spec and had to modify the cage. Thanks Perro

[texlurch]

Before you cut anything, verify the ejector is riding up in the slot of the bolt carrier.

Worse thing would be to take off too much on the bottom, and need to raise it later.

[Perro]

nope
what im saying is special weapons initially made the mold for the cast receivers
they popped the cast receiver out of the mold, and finish machined them to fit (in several areas)
The special strapons guns sold for around 1k though

later, century arms begins the production of there stuff using the same dies, and since they sold there guns for half that price - around 500, you didnt get a whole lot of professional fitting for the price.


you got a casting that needs finish machined basically

pay REAL close attention to the mag release area as well
pop a mag into the magwell with your bolt locked into battery and look through the hole where your mag catch installs to - does the hole of the receiver match the hole of a new unused STEEL mag?? if not, make it, and this is a HIGH PROBLEM area with these guns, so measure 5 times and cut once ;)

[Perro]

i should add that USUALLY the mag isnt allowed to go far enough into the receiver to lock up perfectly

most people fire up a belt sander and remove metal off the bottom of the cast magwell till it just fits

to do it professionally, obviously youre going to want to use a machine tool with leadscrews for a precise amount of material removed per pass

usually the magwells are too long on the cast receivers, so remove the material on the bottom of the magwell until the mag stops on a NEW STEEL mag come to rest on the bottom of the magwell where it ligns the catch on the side of the mag up with the hole for the mag catch

make sense?

[texlurch]

Also watch for the block at the rear of the magwell where they made the shelf.
Sometimes these are not in the exact right spot and stop the mag from rotating all the way back.

[Perro]

the cast receivers dont have a paddle block, the entire bottom half of the magwell is open

[texlurch]

ahhhh that would aid in the installation of a paddle release... hmmmmm

Guess I should pay more attention to my cast CETME..

[Perro]

im not even sure he has a cast receiver, but this is a problem with them, so im only assuming

[roland3]

Ok im doing a build from a century cast ss reciever.the reciever is still bare. i dont have the trunion in yet. it is already machined in the area we were talking about where the fcg cage buts up underneath, as well as the bottom of the mag well. I installed the mag catch and it seems to be right on. it takes the mag fine it goes in until it hits the stops on the mag and it fits good. how ever my previous question was just where to remove stock from to get the trigger housing to go all the way up with the fcg in it. it goes all the way up with out it. i have already established the cage is hitting the Already machined tabs on the bottom of the reciever. I think I need to take alittle more stock off the tabs.

[texlurch]

I would stop, and wait until the barrel and trunnion are in, so you can verify the ejector placement.

Much easier to remove material than add it back.

[rustypirate]

+ 1 for Texlurch, wait until you can get the bolt carrier installed properly before making any adjustment.

The FCG does not go all the way up until it meets the rounded part of the receiver. the ejector hight must be set correctly, and the lower receiver shelf must hight must be set too.

[Perro]

damn fellas you guys are confusing ME, and i understand this thing

you dont need a barrel and trunnion in it to install the bolt set right?? The carrier rides on the rails of the receiver, and that placement has nothing to do with the barreled trunnion right?

The ejector doesnt come close to the bolt set until the bolt is unlocked from the trunnion and on its recoil pulse - the back of the carrier has to be touching the back of the ejector lever to even cam it, and thats no where near the barreled trunnion right??


Why does he need the trunnion and barrel installed to check this??
the placement of the lower receiver is not affected by the barreled trunnion whatsoever

or am i misunderstanding whats being said?

[texlurch]

No Perro you are right, he just needs the bolt in there. But I haven't seen him mention that, just measurements on the receiver that look off a bit...

Actually easier to see the ejector with the trunnion off... wide open and stuff!

[rustypirate]

I have always adjusted it after putting the barrel and trunion in just to be sure. some receivers have quite a bit of slop in the fit of bolt carrier to the rails.

[jfowl31]

a picture of where its not "fitting" correctly would be a massive help.

+1 to what everyone else said though.

[grifter95]

I had the same problem as roland3 on my CETME build. The with out the fcg cage in the lower fit flush to the reciever. However with the cage installed, the front of the upp would go all the way up, but the rear would not. This made it look wierd and made the stock pin holes not line up. I cliped the thinned the tabs off the bottom of the reciever. This helped some. Then the took the stripped FCG shelf and removed metal from the top by placing it on a flat belt sander. I took metal off until the fit was correct. My resoning for taking it off the top was b/c this would not change the location of anything in the cage in relationship to the lower. It only would change the location of the upper to the reciever. This worked perfectly for me.

[roland3]

that is similar to what I did. mine fits nice now. i put the bolt and carrier in and zip tied the cage with the trigger parts in it up to the bottom of the reciever and checked the height of the ejector. took stock off the reciever until the ejector was about .10 or .02 from the slot in the bolt and then took the rest of the stock off the bottom of the tabs on the cage.