Welding Rails

[11C ABN]

I would like to say "Thank You" for every ones input and information on CEMTE RIFLES. I'm planning on Tig welding rails on my receiver for structural reinforcement and adding rigidity to the rifle.

I have been informed that one of the best routes to facilitate this option is to use two stripped bolt carriers (back to back) in the receiver during the welding portion of the build for heat sinks? What other bits of important information do you members have for me when I start this process?

I'm also requesting any information from any one that has used AZEX 1913 Picatinny rail on their PTR receiver build. I like this current option and would like to hear back from any of the members?

P.S. Any one have two cheap stripped bolt carriers for sale?

[casey439]

wouldn't need bolt carriers just a couple pieces of round alum stock. if you wanted to get fancy you could tig them together to make it a one piece

[casey439]

well i got bored at work the other day and was thinking about the heat sink so i made one to weld my rails here are a couple of pics of how it turned out

[okie shooter]

Heck with that much, or a little more you could work up a forming mandral for makeing home made receivers. That thing should work great for heat sinking that receiver.

[Grasshopper]

Welcome! Good to see some other people like ourselves building these fine rifles. :rockon:

[casey439]

thanks, well i am working on a 1 cetme and have three hk's to build, these are going on JLD recievers with rails that i'm going to weld on. as soon as i can find the dealer at the gun show i went to in wilmington i will pic up 2 of the cast stainless recievers he had them for a good price.....really to bad i don't remeber where i put his biz card :icon_sad:
i did get a navy grip yesterday in the mail i have to thank the group for the heads up on $100 complete grip & they had PSG! trigger shoes cheap too so i had to get one i will just make a trigger to fit it. the origianl triggers are .083 to thicksorry the shoe pics aren't that clear

[Smokehouse69]

I'm missing something here, what are you welding? I know you weld in the trunion and the cocking tube, but what else do you have to weld in?

[The Great 308]

I'm missing something here, what are you welding? I know you weld in the trunion and the cocking tube, but what else do you have to weld in?

I believe he is going to weld in receiver reinforcing rails like those used in the HK21, MSG90 and PSG1. These stiffen the receiver and help with accuracy.

[casey439]

yes rails were added to the PSG1 to help the accuracy
here is my reciever in the white
2540
and with the rail laid in place
2541
2542
and the rail sitting on my CETME
2543
it doesn't fit on the century reciever anywhere near as well as it dose on the JLD reciever, the rails i got from PTR.com for $20 i ordered a set thinking i would make the other i would need for my other builds but they fit so well it isn't worth my time to reproduce them

[Buelligan]

Casey439 , That is nice work ,You are the MAN.:thumbup:

[M1 Tanker]

Casey, to help you a little with your pictures, there is a MACRO setting on your camera. It will allow clear close ups.

I'm watching this thread, ya'll have to attention. I'm curious to how much these improve your accuracy.

[gunnysmith]

Does HK use a spot welder or TIG

[Seattlefungus]

Both... The seams on the underside of the receiver and trigger housing is tig and cocking tube, the trunion in the receiver is spotwelded... (They also tig the underside of the buttstock metal...)

[gunnysmith]

I was referring to the installation of rails only, is that TIG?

[casey439]

to tell you the truth i don't know i don't see any welds on the PSG1 check the pic i plan on running short beads to reduce the chance of warping even though i made the heat sink

[WildBillCody]

I remember someone, years ago, welded rails on thier rifle and it never worked right again, maybe they didn't use the heat sink.

[gunnysmith]

Just wondering if spotwelding was the factory way. one should be able to see the dimples through the ejection port from the spot welder.

[Simon]

to tell you the truth i don't know i don't see any welds on the PSG1 check the pic i plan on running short beads to reduce the chance of warping even though i made the heat sink
In that picture it looks as though there are some short tac welds, maybe about an inch long, running along the bottom of the rail (and attaching it to the receiver). They look very thin, look for the short shadowy areas under the rail.

If I remember right, you'd have to do similar welds along the top to minimize warping. But I am an amateur welder at best.

[dirty8]

I'd personally go with RDTS rails. The RDTS rails are closer to PSG/MSG design than the JLD. The JLD rails look like the same material used to make collapsable stocks.

[gunnysmith]

In that picture it looks as though there are some short tac welds, maybe about an inch long, running along the bottom of the rail (and attaching it to the receiver). They look very thin, look for the short shadowy areas under the rail.

If I remember right, you'd have to do similar welds along the top to minimize warping. But I am an amateur welder at best.

I enlarged the picture and those are not weld beads. They are 2 small rectangular openings.

[okie shooter]

I wonder if HK, if when they weld the rails on, then restrightens the receiver with custom equipment, thus a stronger and stright receiver. I imagine they have or had equipment at the factory that would allow for tweaking any imprefections after the rails or for that matter the trunion is welded into the receiver. I would think the trunion being square with the receiver is more critical.

[The Great 308]

This is some info that I combined from a few different posts on the subject on HKweaponsystems.


Factory PSG1 has 5 welds on the top and bottom of each rail. They also pin the front. I know Urbach does this but I am not sure exactly how. Some people skip the pinning when building clones.
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To be more specific about the welding.....the edges of the rails lay on the receiver....so, they are technically 'lap welds'. They are done in a stitch weld pattern. The stitches are also staggered. IOW, wherever there is not a weld on the top of the rail, there should be a weld on the bottom....and vice-versa. <o:p></o:p>
When the welds are being done....it is very important to control the heat, to control warpage. So, make only one weld at a time, then, allow that weld to cool enough that you can lay the back of your hand on it. (As you can imagine, this job takes some time, mainly due to the wait between welds) <o:p></o:p>
Alternate welds, and sides of the receiver. In other words, put one weld on the upper right, and then maybe the next one on the lower left rail. Alternating the heat also controls warpage. Continuing to weld in the same area over and over again without rotation will lead to warpage. <o:p></o:p>

To weld my rails, I used about 35-40 amps on the TIG welder. I also used a high nickel content filler rod. (Not sure what the rods were, my gunsmith supplied them for the job...I think they are available at Brownell's) <o:p></o:p>


I also agree with others here that the RTDS rails are supposed to be much better than the ones sold by PTR.

[gunnysmith]

http://alpinetek.netfirms.com/guns/MSG90A1/
check out this guys page

[The Great 308]

http://alpinetek.netfirms.com/guns/MSG90A1/
check out this guys page


That is an interesting clone however according to my research over the last couple of years the receiver rails are not welded on the way that HK does it. You can see in his pics that where there is a weld on the top of the rail he also put a weld on the bottom this is not correct the welds should alternate. I will try to find a close up pic that shows this. I am not sure if it really makes a difference but I figure HK did it that way for a reason.

[cz777]

i have been rebuilding a ptr-91 which needs TLC after a buffer [ please look at all ptr made buffers]failed which destroyed the stock [webbing around the buffer hole ]new hk stock and what started trouble was the bolt gap dropped to .002 !YES this plants some seeds in the brain for fun and work !DAMN nice toy!!!mmmmm!

[casey439]

i sure would like to get ahold of a copy of prints for a Forward Assist so i could add it to mine.... i refuse to pay $350 for one

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