1st build getting started questions

[roland3]

I have the reciever now and the old kit demilled. i convereted the trigger to semi auto and have new standard sized rollers on the way. what is the fist step as far as installing the trunion and barrel. I have read several tutorials and 1 said install the trunion 1st then press barrel in.l the other said press barrel in to trunion 1st then install in to reciever. Is it possible to set the bolt gap before the trunion is in the reciever? I guess I dont really understand how the relationship between the barrel and the bolt face affects the gap in the back of the bolt to the carrier. I have seen the diagrams and it looks to me like the rollers lock in the trunion once they pass in far enough. so once the head is locked in, how does the barrel affect where the carrier is.
also what is the best way to fit the trigger housing to the reciever. should I mill off the tabs, or mill the inside out of the housing. does one way give more support than the other? is there any other prep work to the reciever I need to do first? any help is appreciated. and i have read all the tutorials, just looking for other input. thanks

[rustypirate]

OK, pressing the barrel into the trunion affects bolt gap because it alters the distance that the bolt head travels into the trunion well before mating with the barrel face.

the fruther to the rear the barrel is, the sooner the bolt head encounters it as it enters the trunion, and the larger the resulting bolt gap.

Your best option is to install the trunion into the receiver first because the receiver will help to stabilize the bolt carrier as it mates with the trunion to measure the bolt gap.

Next install the barrel and press it into the trunion from the rear, stopping when you get close to having the barrel flush with the inside face of the trunion, but still slightly protruding.

Install the complete bolt/carrier assembly into the receiver and let ti lock into the trunion.

Check the bolt gap and adjust the barrel depth until you get the gap as close to .020" as possible without having it over .020"

then drill and pin the barrel through the trunion in the provided barrel pin hole.

Install the cocking tube and triple frame, and you are done.

As for the FCG, some people like to mill out the inside of the tabbs at the front to go around the receiver shelf, but this is more for appearances making the FCG look original. Century and JLD for that matter, just cut the tabbs off flush with the front face of the grip frame to get them out of the way.

As fro prop work on the receiver, it depends on which receiver you have, and even then, they vary greatly depending on the QA of the manufacturer.

The Century Cast receivers are all a bit long on the rear end, and will have to be filed down until the stock pin holes line up. Some people have reported issues with teh inside dimensions being slightly off on the mag wells requiring adjustment there too.

[roland3]

hey thanks a lot for clearing that up, that was the original plan, I just got confused after reading some other threads.. one more question. do I need to have the trigger housing fit on the reciever before trying to set the bolt gap? one tutorial said to pull the trigger and let the hammer hit the carrier before you check it. or was that just for checking the gap on a normal rifle. oh ya ,one more queston, the reciever is about .005 smaller that the diameter of the front trunion, should I loosen up the fit so the reciever does not expand when I tap in it with a mallet or wont it matter. it seems to me that the reciever might bow open if I tap the trunion in and the fit is tight.

[rustypirate]

The bolt gap SHOULD be measured with the hammer down on the firing pin however, if you get it close to .020" then the difference in gap generated by the trigger should not make that much difference, maybe a couple of thousandths.

As far as the trunion fit, it needs to be snug, not press fit, but not sloppy either. Tap in with a mallet should be fine. you can use some emery cloth or even one of those flap-wheel type abrasive tools that go in a drill for stripping paint and such to polish the inside of the receiver, or just use emery cloth on the trunion.

[roland3]

whats the deal with the mag catch, is the lever eliminated? not quite sure how that workes. is it just push button style?

[rustypirate]

The factory stock CETME rifles had both the push buton and the "paddle" mag release. Most manufacturers of the rifles for the civilian market have done away with the paddle, but there is a procedure for installing one.

It is complex due to regulations from the ATF about drilling holes and inserting pins into the receiver without converting it into what they consider a "machine gun".

[roland3]

ok, that makes sense, thanks