Modifying a Tapco flat for an underfolder kit

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[ARCHIVED THREAD] - Modifying a Tapco flat for an underfolder kit

Posted: 3/30/2006 12:31:15 PM EDT

I have a few Romy kits here, and I want to build a Romy with a Yugo underfolder. I have the rear receiver stub, and the rear underfolder trunion. My question is about cutting the UF holes in the flat. What do you guys do about the forward fixed stock trunion rivet hole? It seems to be in the way. Maybe it would be covered up by the underfolder stock pivot though.

I have a bent tapco flat here and a couple DCI econs. I don't really like the idea of hacking up the DCIs. I would feel much better cutting the bent Tapco. Has anyone done this, are there any how-to's?

I could just fill in that forward rivet hole with weld. The rear rivet hole looks like it will line up.

I don't think trimming the rear of the receiver to fit the slanted shape of the Yugo trunion will be a big deal.

Posted: 3/30/2006 1:21:23 PM EDT

[#1]

A couple more questions: It seems like the Yugo UF trunion is narrower than the Romy trunion. I measured the Yugo trunion to 1.21, while the Romy measured 1.25. While this isn't a lot, it does create wiggle room when I slide the trunion into my flat. Is this normal? What do you guys do to compensate?

Also, there is a spring loaded pin that goes through the rear trunion and receiver just below the recoil spring dovetail. What is this for? I am just wondering if I need to include it on the Romy UF build.

Posted: 3/30/2006 2:17:58 PM EDT

[#2]

The yugo is a little thinner, if you use that trunnion it will probably draw up the receiver around your rivets. Also why not just bend a TAPCO flat w/out the trunnion holes? Info on the yugo rear trunnion difference can be found at www.gunsgutsandgod.com

Posted: 3/30/2006 2:43:19 PM EDT

[#3]

Quoted:
A couple more questions: It seems like the Yugo UF trunion is narrower than the Romy trunion. I measured the Yugo trunion to 1.21, while the Romy measured 1.25. While this isn't a lot, it does create wiggle room when I slide the trunion into my flat. Is this normal? What do you guys do to compensate?

Also, there is a spring loaded pin that goes through the rear trunion and receiver just below the recoil spring dovetail. What is this for? I am just wondering if I need to include it on the Romy UF build.

I built my UF/Romy on a Tapco flat, with no pre-drilled rear block or trunnion holes, I simply used the cut receiver off of the UF rear block as a template, and drilled my holes undersized. That allowed my some play after the flat was bent to align them up correctly. Since my front end was Romy, I didn't have any issues, but I have heard that the Yugo trunnion is narrower, and requires a Yugo receiver.

That springloaded pin only seems to serve as a retainer for the recoil spring assembly...no idea why it's needed.

Posted: 3/30/2006 2:53:13 PM EDT

[#4]

I thought buying a yugo UF to use on a Romy kit would be a good idea. Should have done my homework.

Posted: 3/30/2006 3:50:55 PM EDT

[#5]

Why not just add some shim stock to the rear to make up the difference?

Posted: 3/30/2006 4:34:55 PM EDT

[#6]

Wouldn't this throw off the outside thickness of the receiver? I don't know how much room there is on the UF hardware to play around with, but I would think the threaded rod that goes through the trunion would not be long enough.

Posted: 3/30/2006 4:44:43 PM EDT

[#7]

Fellow member Pedro66 built his Romy front end on a Tapco flat with a Yugo underfolder rear. He just sanded down the rear trunion block on each side slowly until it fit snug in the back of the receiver. He used a Tapco blank but you don't have to. You can feal the other holes in after you cut the new ones.

thanks,
Ron

Posted: 3/30/2006 4:49:46 PM EDT

[#8]

But the rear trunion is too narrow, not too wide.

Posted: 3/30/2006 6:07:38 PM EDT

[#9]

Depending on how much thickness you need maybe able to use some steel off the cut reciver that you pulled the trunion from.

Posted: 3/30/2006 6:57:38 PM EDT

[#10]

That's a good idea, I need to experiment with that.

I think for now at least I will start searching for a sidefolder.

Posted: 3/30/2006 7:26:33 PM EDT

[#11]

I built a romy with a yugo under using a ewbank receiver. Yes the yugo rear is smaller so I did some measuring and used some stainless sheeting for shims I got at a local machine shop. I don't remember the thickness but is was only a few mils thick. Worked great and nobody would know it unless I told them to look for it.
If you don't use the shims then you will probably have a tight fit on your carrier.
It's very doable!

Good luck!

Posted: 3/30/2006 7:52:23 PM EDT

[#12]

It looks like you will need .040 shim total, according to the measurements given of the two different trunnions.

Posted: 3/31/2006 5:34:26 AM EDT

[#13]

Good idea on the stainless flashing. That is a very workable option.

Posted: 4/2/2006 1:20:30 PM EDT

[#14]

The Yugo trunion is made for a 1.6mm receiver.

Posted: 4/2/2006 2:23:37 PM EDT

[#15]

I am cooking something up, I'll post some pics when I finish it. Right now I am trimming the upper rails.

Posted: 4/2/2006 2:57:20 PM EDT

[#16]

Polish Underfolding Flats.....Made from a Tapco Flat......

Roger

http://www.copesdist.com/ak47.htm

Posted: 4/2/2006 4:15:52 PM EDT

[#17]

Yeah those are nice. Since I was using a Yugo rear trunion I needed to mod the flat anyways.

Posted: 4/2/2006 6:35:26 PM EDT

[#18]

the yugo's have an angle the rear trunion and the polish rear trunions are straight. are these straight or slanted

Posted: 4/2/2006 7:15:43 PM EDT

[#19]

I came up with a solution that worked out pretty well.

This is what I was up against, lots of room between the trunion sides and the receiver. The Yugo was built on a 1.6mm receiver, so there is extra room, since I'm using the 1.05mm tapco flat.

I had a sheet of metal laying in the garage, it ended up working perfectly.

I spotwelded the shims using the rear trunion holes Tapco had cut into their flats

I think it's going to look very clean once it's painted.

It obviously needs fitting here and there, and I am going to have to move the lower rail rearwards on the Tapco handguard, but you can see the stock worked out pretty well.

Definite fitment issues with the rest of the rifle, but the stock is going to work out fine as soon as I punch all the pins in. (yes I know the muzzle brake is not on all the way, there is no trigger, the mag doesn't catch, the stock won't fold all the way, etc.)

Posted: 4/2/2006 8:12:19 PM EDT

[#20]

very nice job hoohaa.....looks great!
its getting there!!

Posted: 4/3/2006 4:57:33 AM EDT

[#21]

Thanks boss. What do you trim usually to get the mag to seat properly? The lip of the front trunion?

Posted: 4/3/2006 7:27:54 AM EDT

[#22]

Are you just trying to tease us with that muzzle break?

Posted: 4/3/2006 8:20:06 AM EDT

[#23]

Just trying to get a "rise" out of you...

Posted: 4/3/2006 3:44:46 PM EDT

[#24]

Quoted:
Thanks boss. What do you trim usually to get the mag to seat properly? The lip of the front trunion?

On the 2 builds I've done I had to file down a little of the mag well just above the front of the trigger gaurd to get the mag to lock in. Just a hair though.

Posted: 4/3/2006 6:57:58 PM EDT

[#25]

hey brian....i take alittle off the trunion where the front of the mag catches(lip) and also alittle off the rec right below the mag catch on the trigger guard

same widrh as the trigger guard mag catch(the part that u push to release the mag) JUST ALITTLE AND KEEP CHECKING OFTEN!!!

[ARCHIVED THREAD] - Modifying a Tapco flat for an underfolder kit

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