ok so im building a yugo milled underfolder kit using a laser cut receiver and just welding the rails in place and then welding the receiver to the barrel stub/trunions/metal block thingy. Anyhow after a little handfitting i have the bolt carrier sliding down the rails all the way forward and backward like silk but when i put in the bolt in it doesnt want to slide into the locked position at all. I think that theres a little jump up in the space between the lower rails on the receiver and on the inside of the trunion. I have already welded the lower rails in place and i dont think i can move them but the transition time when the bolt slides from rail to rail is very stiff. any thoughts or ideas. im having trouble getting my file in there to fix it.

I'm a newbie, so don't take me too seriously.  Would a not so rough dremel mini-grinding wheel fit in there and allow you to fix it?  I guess it's also a question of how much metal needs to be removed, as you don't want to weaken things too much.   Good luck!

If your lower rails aren't too far off you can use a hammer and a punch to coax them up a little.  I have adjusted more than one set of rails with a hammer and a punch.

What dalesimpson said, if you welded the rails in correctly, it will be a PITA to remove them.  Use a punch & hammer and coax them up.  Best of luck.

Are you sure it's not the ejector causing the problem?

Quoted: Are you sure it's not the ejector causing the problem?

That is what Im thinking, just watch the bolt go forward and see if it is hitting on the ejector, If it is, get out a hand file and do a little fine tuning work.

no the ejector is just fine and the bolt carrier slide on the top rails perfect but when you put in the bolt it hangs on when it trys to cross over from the lower rails on the receiver to the lower rails on the trunion. basically the lower rails on the receiver were installed just a smidgen too low. im planning on hammering the right one up just a bit and doing a little dremeling to alleviate the problem.

also someone said to check my welds for cracks while shooting i figured that mig welding the thing together would be a million times stronger than rivets. has anyone ever had a problem with welds breaking and do i need to be concerned with the longevity of this build, im doing welds because i thought i could make it last forever.

I've run into instances where tho bolt will slide by the ejector fine, until the bolt tries to engage the trunnion.
There is enough play in the receiver for the bolt and carrier to pass by the extractor even when it is a hair too long, but it wont lock up.

I encountered a problem like this last night with my second build. My bolt would jam with the magazine in it. When I put a different bolt in from a different kit,  it slid fine... I compared the 2 and it looks like the bolt that was jamming was fatter where it passes through the magazine/follower. I'm convinced that most of these Romy-Gs were never fired or tested...

yeah i was kind of surprised by how much "hand fitting" i had to to on the first two i built. I know that im welding everything instead of riveting. And riveting would probabally center everything in place more accurately and im just basically eyeballing my measurements and welding it up but on my second build i had to do alot of trimming on the upper rails and the lower rails are in there a little low meaning that i welded the receiver to the kit just a millimeter or so to low and now im having all kinds of headaches. I had no idea how easy it was to build a rivet kit untill i saw yesterday how yall are modifying bolt cutters. I think that im going to build another kit in a few months when i get some more money together and im definately going to do a rivet build. It will look factory and heck if it ever falls apart i can just re rivet the thing!

i think getting another laser cut receiver blank thats bend by hand and weld the seams would be the cheapest and easiest way ever to get the receiver to shape and then riviting it would make for a complete build in probabally a few hours! as they say hindsight is 20 20!

Did you install a TAPCO hammer?  I had the same problem with a TAPCO hammer.  With the stock hammer the bolt carrier worked fine.  My problem was the contour of the hammer---I had to grind a tiny bit off the part that would bind the bottom of the bolt carrier.  I could work the carrier to the rear (pushing down the hammer as needed) but when the carrier would start to move forward, it would bind.

I wish I had seen this post earlier.  I went through this stuff on my Tapco flat build this week.  I had to coax the ejector rail up a smidge with a hammer and punch, and then I had to grind a little material off the ejector as well, it was causing the bolt to wedge against the mag lip on the other side.

Quoted: Another thing to look at is if the trunnion is in the receiver straight, not canted down in the front and raising the rear. Mike

This is more than likely the problem.  If the rails were the problem, you would get a bump when the bolt made the jump, but it would still lock up OK.  The lower rails dont control lock up.  Chances are that the trunnion/barrel is out of alignment with the receiver.  This causes things to bind up as the bolt attempts to lock up.  This is a common problem and I can see it easily occurring with a weld build.  Look down the length of the rifle like looking down a cue stick.  Chances are the barrel will look like it is angled down.  Another way to check is to see how well the gas piston lines up with the gas port (with the gas tube off).  Good luck.  This is sometimes a difficult problem to solve.

thanks for the help yall but i completed my build a few weeks ago,

what i would like to know is what do i have to do to make a yugo legal.

its basically a origional gun with a mig welded flat on it. I refinished the stocks and ground down all the places on the trigger group that were designed to be full auto ex. front of hammer, left back side of bolt carrier, side of saftey, ect.

Ive been told that any significant modification to a part could count as an american made part. it this true or do i need to buy an american made FCG and a slant brake?

You can coat everything with red dykem and put it together and cycle the bolt, then take it back apart and see where it is rubbing or hanging, just a thought.

Quoted: thanks for the help yall but i completed my build a few weeks ago, what i would like to know is what do i have to do to make a yugo legal. its basically a origional gun with a mig welded flat on it. I refinished the stocks and ground down all the places on the trigger group that were designed to be full auto ex. front of hammer, left back side of bolt carrier, side of saftey, ect. Ive been told that any significant modification to a part could count as an american made part. it this true or do i need to buy an american made FCG and a slant brake?

You need 6 parts...

American made FCG (tapco G3) =3

Receiver =1

slant brake =1

Gas piston=1

That is how I would do a rifle, but you can change a couple of other things like the pistol grip and the stock set... I would not just grind on the origional FCG and call it us made...that is asking for touble down the road.

parts are cheap, do it right, do it legal.