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Discussion Starter #1
Hello all, I'm about to embark on my first receiver rewed. I've read up on this forum and several others, I believe I'm about ready. I would like to know from you re-weld veterans out there what you wish you had known/done before starting your project. Also, there's a lot of back and forth discussion I've seen on welding rod/wire. I'll be mig welding, that's what I have. What wire or rod did you use on your receiver and how happy are you with the results?
 

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You’ll want to find the Pirate/ Project Guns reweld instructions, as they are both step by step and ATF approved. Maybe they are archived somewhere?
 

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Invest in a TIG set up. That's the recommended type of welder for receivers. The MIG can work, but, it puts a lot more heat into your piece and is more susceptible to voids in the weld.
 

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Hello all, I'm about to embark on my first receiver rewed. I've read up on this forum and several others, I believe I'm about ready. I would like to know from you re-weld veterans out there what you wish you had known/done before starting your project. Also, there's a lot of back and forth discussion I've seen on welding rod/wire. I'll be mig welding, that's what I have. What wire or rod did you use on your receiver and how happy are you with the results?
I remember the discussion about only using a specific kind of rod/wire. I think it had less to do with strength and more with aesthetics. My receiver was reweleded by a guy with a TIG setup. He used all the recommended stuff. One small part cracked and I had no choice but to fix it with my Harbor Freight flux core.....and it worked out just fine.

What are you using for the trigger/bolt conversion? I used the TNW kit and was absolutely horrified. The sear in their kit was WAY too short (I had to get a few custom made) and the trigger pull was horrible. (This WAS about 15 years ago, so Im assuming their design may have been improved.)
 

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Discussion Starter #5 (Edited)
Hello Abominog nice to hear from you, I've seen you around quite a few places. I'm actually looking at getting one of your MG 34 reweld fixtures. You're have one up for sale still? I've found some good instructions but I'll see what I can find from project guns.

@iendecker yes I am worried about voids and heat is definitely a concern. I like to go that route but I can't see buying a TIG at the moment though and learning to use it. I'd be better off buying a new TNW receiver for the cost and use I'd get out of it anytime soon. Maybe if I pick up another project after this I'll learn to TIG weld.

@ScottD You've hit the nail on the head with my biggest concern, cracking. That's the main reason why I haven't chosen my wire yet. I am planning on going TNW, IIRC they've made improvements, but that may be to the receiver. I've read through the thread you mention a couple times it does start getting into aesthetics.
I hear using the original firing spring vs the TNW one will make the trigger much better if you don't need it.
 

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"I hear using the original firing spring vs the TNW one will make the trigger much better if you don't need it. "
I used TIG on mine and the proper fixture and patience are key and I also use the original firing pin springs. You can throw out the TNW springs and with some work get a very reasonable trigger.
 

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Discussion Starter #7
I used TIG on mine and the proper fixture and patience are key and I also use the original firing pin springs. You can throw out the TNW springs and with some work get a very reasonable trigger.
Yes, I definitely plan on going slow and watching temperature. Do you remember what type of stick you used? Did you do a Post Weld Heat Treatment (stress relief) on the receiver afterwards?
 

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If your gonna mig it use ER70S wire. Go with a larger dia. to fill the gaps (.06 or .09). For relief after your done you can hear it in your oven and let cool with the door closed. Check pirate 4x4s tutorial if it's still up
 

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Discussion Starter #10
Just checked, calguns tutorial is still up. Sorry but don't know how to post link
It's okay, I have it saved.

I'll go with ER70S then sounds right for this type of project.
• General shop applications with poor fit-up or rusty, oily plates
• Steel castings or forging salvage

I'll just need to get a reweld fixture and get to it. Thanks
 

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Well for a first receiver you picked a hard one to do. Good Jig is very important. Make or buy one. Several folks have done this receiver. So it can be done. One KEY is to do small areas at a time. If you are a good welder on other projects then don't take the passes that you would normally do. Small areas in different sections or it will warp. With a TIG you will have some very deep areas to fill it. Some folks MIG fill in the deep then TIG the top area and get a better job.
My laptop went South and I'm still rebuilding and finding things. I believe that I have a copy of Stan's Project Guns MG34 weld up someplace. I did print a paper copy for myself a while back. Need to find and rebuild a lot of things. But will check out what I can do for you and post back in this thread when I can and find the info.
Also check the brp guns website for as much info as you can get. Also review John's books at
Again Good Jig or you will be grinding and cleaning for a long long time.
GOOD LUCK.

Stay Safe

Later 42rocker
 

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Discussion Starter #12
@42rocker Thanks for the feedback. I have the tutorial on Calguns by Kiwi, it's really good. My gun came with John's books, I'm really fortunate with everything it came with. Fortunately the front section is mostly saw cut so that should be (hopefully) straight forward but he back end will need some filling. I feel a lot more confident now with everybody's input. I'll go slow one small piece at a time. I plan on purchasing one of Abominog's fixtures. The biggest pain is this this was partly welded together as a dummy. I'll be cutting it into proper pieces tomorrow to start the prep work.

On another note, anybody got experience installing the bolt cams? They were removed prior to reassembly as a dummy. I have another set, but I think I'll go to a gunsmith for them. TNW will install them, maybe I'll see about making a trip to them for installation they are about two hours from me.
 

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Back in the old days, when receivers were being rewelded as semis and dummies en masse, there was much discussion about TIG vs MIG and the type of wire. I don't remember all of it, though it seems that a variety of metals was used with success MORE dependent upon welding skill than the metal.

That said, at least one Project Guns semi receiver (and probably more/ all) used a high content stainless, the result being that it would not blue, and even with Brownells 84 it's iffy. The MG34 receiver is not a good choice to paint, as the tolerances are tight.

As far as filling gaps, I recommend against it for semis and SOTs. Butt-ended sections is far better; with filling, there is absolutely no way to weld-fill the proper internal contours that support the bolt.

Nor would I ever bother using anything but original installed cams.

For dummies, filled with weld was the old standard. IMA's most recent receivers (not MG34, they're past that) employ a false section (i.e., not original receiver chunk) to satisfy ATF (so says IMA.) I'm no expert, but ATFs requirement is "not readily convertible to FA".

By following the old Project Guns semi conversion, installing a bolt block and weld-filling the grip parts that go through the receiver, and THEN welding in a block of steel, achieves two things (1) it's a semi at best, not a FA; once those holes through the receiver are weld filled there is NO WAY, with any machine or other, that they can be "dug out" to revert and (2) demonstrates clear intent to build a dummy.

Further, removing the cams IMHO makes it useless, and only a top machinist/ gunsmith is going to ever be able to properly install them. As far as I'm concerned, an original MG34 receiver without cams would meet ATF's "non convertible" definition, nor would it be a firearm (since the bolt won't rotate to lock) and since even a specialist won't be able to install new cams, timed properly, rivets flush in six or eight hours, whatever the metric is; and then there's timing the cams to a barrel. Clearly, my definition of a (live) receiver is different than ATFs, but I would really like to see somebody source and machine rivets, then re-install cams and do all that other work with ordinary tools in eight hours. If it could be done properly (even with a machine shop!), I'd be impressed. But that's my opinion.

As far as TNW's semi parts go, consider them to be "rough castings." Better than nothing, but plan on HOURS of hand fitting, and that's with an experienced machinist's eye; if one is not experience with high precision fit, measurements, and mechanics there will undoubtedly be several "issues" with any given set that will stop your project dead. AND there is the added complexity of stacking tolerances in the original parts PLUS induced variation with a reweld. @ScottD nothing has changed with the TNW parts.

As if that's not enough complexity, the original MG34 were made by different factories, on increasingly worn tooling and every one was HAND FITTED. So if you have a front end (shroud) you want to use, check timing on the receiver lug/ front end FIRST, lest you reweld a semi or dummy or SOT that doesn't match up. This wartime hand fitting is the reason (1) TNW parts don't drop in...well, partially the reason and (2) if you read various build sources for bolt conversion, you'll see differing dimensions...which to use? Well, the one that best fits your gun! Good luck!
 

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Abominog
Lots of interesting statements. A few good points that I've not heard raised before also. Need to review them.

Grains of Freedom
As I understand it right now there are three different ways to do a receiver.
1st Obtain cut/torched parts and weld
2nd tnw receiver
3rd philadelphia 80% receiver
From the old days the tnw receiver was roughed in, then broached using a large number of broaching tools. Wow I remember those pics that used to be on the tnw website. Just like the Germans used to do.

From everything I've read seen the philadelphia 80% receiver has never been made workable. Made as 80 dummy and is just that. A casting that looks good and great for those wanting a dummy.

As far as cams go, they were replaced by the Germans at some point in time. I don't know what level they were replaced at but they did do it. May have been in the field or sent back to the next level rebuild station or even back to the factory.

So back to the topic of the thread.
1st receiver weld up. Good Luck as you can see the one you picked is going to be a hard one.
If you are thinking about a trip to tnw. GO Enjoy, if they will take the time out to show you the mg34 receiver building stuff. Talk to Tim owner tnw about it before hand. I know that it's a visit that I would like to do.
Think and review. Long Hard project. I hope to do someday if God grants me time.

Stay Safe

Later 42rocker
 

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Discussion Starter #15
@Abominog Fortunately my receiver wasn't that bad off. it has a piece of round stock in the barrel tension rod spot that held in place by the weld the holds the two front pieces together. It then had a piece of steel run through it and welded into place. This gave it the support to hold everything together. Fortunately whomever put the dummy receiver together was interested mostly in aesthetics because most of the welds don't go all the way through the receiver, have poor penetration and avoid the bottom completely. I'm looking at about 1/8" gap in the front and about 1/4" in the back. That's with the cuts cleaned up already. Not optimal I know, but I have some ideas.
As for the cams, I have an original set and they fit perfectly flush with the leading edge, against the inside and into the grooves. TNW has a video on installing them, the actual work takes them less that two minutes, check it out: /watch?v=XnE8FeBEatE This is why I'm likely going to pay them a visit. Then I can source the bolt parts. My gun came with TNW instructions on how to do the mod, but I don't have any of the parts (that I found). Clearly the previous owner wanted to do it but didn't. Then again he already had two transferable Maxim machine guns so this was a back burner toy.

@42rocker. Those Philadelphia 80% do look good and at a glance you might think they'd be easy like an AR-15 lower, but I'm skeptical. Like you've pointed out I haven't heard of anybody converting them and they're up for sale secondhand all the time. Looking at the receiver pictures on their website is looking at pictures of a house up for sale. Sure what their showing you looks great, but want to see what their not showing us.

All in all I'm going to to do the best I can and take it slow and easy, work through it and try to anticipate problems before the happen. This is a project that the is about the journey as well as the destination. As I see it, I started with a dummy gun. If I dummy this thing up, worse case scenario, I'm back where I started with a dummy gun, a story and experiences.
 

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Remember the Receiver is one part that can be removed quickly and put on another weapon. Granted some receivers work better with some parts kits than others. Myself I'm happy to say that I have a brp dummy receiver. One day when talking with Brian (brp) about it I asked how come they left the cams in. He said time. So my receiver has the original cams in the front. Removing the weld parts would only take a few minutes and you would be ready to start adding other receiver parts for a rebuild. I also have a brp xmg16 receiver for the mg34, works great.
Guess what I'm trying to say is that you can have a dummy receiver and be working on another one for shooting later.
Enjoy the Build.

Stay Safe

Later 42rocker
 

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Note. If you use a stainless alloy rod it will not blue or park. And even with out stainless you will most likely have stripes in your finish
 

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TIG it. Much deeper penetration than MIG. Go slowly, doing a little at at time, alternating sides. That will keep the temperature down a little on the receiver sections and will prevent / minimize shrinkage and warping. Slow, slow, slow, a little bit at a time, alternate sides. If you aren’t good at TIG, practice. You’ll get it. Take your time.
 

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. AND there is the added complexity of stacking tolerances in the original parts PLUS induced variation with a reweld. @ScottD nothing has changed with the TNW parts.
The MG34 taught me the meaning of 'tolerance stacking'. Undoubtedly, my 34 was a 'garage' build and still exhibits running issues. I usually get about 4-5 rounds off before I get a failure to fire. Charge it, pull the trigger and Ill get 4 or 5 more. Yeah, this is a VERY tight weapon and its tough to get it running correctly if you are limited in tools or milling equipment. But I keep mine around, no matter how ill tempered it is because of its history. Most of my lower components are pitted to hell.....the receiver has German, Russian and Israeli marks on it.....this gun (or, more accurately the sum of the parts) has been everywhere.
 

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Discussion Starter #20
But I keep mine around, no matter how ill tempered it is because of its history. Most of my lower components are pitted to hell.....the receiver has German, Russian and Israeli marks on it.....this gun (or, more accurately the sum of the parts) has been everywhere.
Sounds like a cool piece of history, If only it could speak. That's what really draws me to a weapon like this. Even if you don't know the weapons personal history, it played a part in a very signifigant part of history. Just looking at it makes you think of old battlefield footage. Lives it may have cut short. The tragedy of our own existance from horrendus things we've done to ourselves. You can have a nice run of the mill gun just like anybody else you purchased or build a "tacticool" AR with a bunch of toys on it. In the end though it just a mass produced product with no interesting past. Eh I'm rambling...
On topic, I don't expect the gun to look perfect or even close. Sure I'd like that but I'd be happy with it functioning. Zebra stripes and weld marks are just like scars on us, they tell a history.
 
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