Opinions on how slick M70 milled receiver should be
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Thread: Opinions on how slick M70 milled receiver should be

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    Opinions on how slick M70 milled receiver should be

    Working my way through my first reweld. The stub pieces have little nicks and dings that looks like they were there before the receiver was blued. They have color in them. I am trying to get my welds as slick as possible and have gone back over all the porosity and voids and continue to mill and file them down. Would you leave the dings that seemed to be there from birth or slick up the whole thing? Don't know about anyone else but it is a tedious process depositing material, avoiding undercut and getting a nice smooth surface after welding.

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    OK. Started cold bluing a milled reweld today. Any tips on getting the inside of the receiver all covered? I am using the gel and was down to q-tips and still don't think I am getting every crevice.

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    i never seen this until now but im glad youre doing this! i feel your pain....
    yes i bet those dings were there before. yugos .... i dont want to say they are better or worse than anything else but i can say w/out hesitation i have more problems w/ porosity on them that any other country.
    also i have more trouble w/ them coming back brownish or purplish from hot bluing than other countries.
    there is actually pores in the yugo metal itself once you have a bunch of cuts one in your hands youll notice it.
    if you boil everything good and hot for a while it lessens some of the porosity issues. i think after a good while of being cleaned and oiled and possibly cosmoed for a time it seeps into the yugo sttel more than others but just a theory.
    as for the colt blue dont be afraid to put it on heavy you could even use a little brush and some heat get the inside and then do the outside last so you can make it even.
    not taking new work

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    BR I am always happy to see your replies pop up. I have done a lot of metal work in my time but this reweld is taxing to say the least. There is some really interesting stuff coming up out of these receiver parts. I tried tig welding but just felt I was getting too much heat into the thinner parts of the sides. After using the mig ( .024 wire in a little Miller 175) I actually got some copper splotches on the surface. I use copper coated wire so I attributed it to that but had not seen that in welding over the years. Series of spot welds kind of print through and I hope the bluing hides some of that. You can see it after sand blasting and I used really coarse media. Even with wire feed turned up and welding cold it is difficult to minimize the undercut around any spot weld trying to fill a void. Too bad these weren't painted from the factory. Sure would hide a lot of the issues. I could use some really low heat filler to smooth everything up. I better get good at it I have some more to do. Thought I really liked milled receivers.........not ready to buy new...yet.
    Last edited by Longshot1; 04-24-2019 at 07:28 PM.

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    Wow I thought it was just me having issues with these damn yugos.
    Not proud of how either of mine came out.

    I just mop the paist on with a cheap brush over and over.
    Sometimes I let it sit and marinate in a plastic bag.
    Longshot1 likes this.

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    i assume youre backing up your weld w/ copper or brass? im not worlds greatest tig welder. actually rather be using a stick...
    lucky for us were milling it away. in our case the most important thing is not getting undercut and avoiding porosity.
    but imo w/ a tig you can put as little heat as needed into an area. its a tough balance of not getting any undercut and getting too much filler.
    seems like too much filler is also too much heat but also more material to retract when it cools, causing warping.
    idk if this is real or jsut something i perceive happening...
    if youre getting pososity i think the only way to fis it is to get rid of the area. like instead of trying to melt over it which will ussually leave behind a bubble still.
    i ussually take a carbide burr on a dremel and cut it out. you need to almost do this before you have the metal removed back to surface level.
    in other words catch it soon. it ussually shows up as an tiny area w/ a little different reflection whn youre removing weld before the hole actually opens up.
    and you can poke it w/ an awl and open it up.
    when youre you can heat the haz up a little when youre done to sort of normalize it.
    this helps a couple things i think. one being maybe getting rid of a real hard area the other helping the blue blend over.
    the last time i did a parked reweld i soaked it briefly in a mild muratic acid solution, kind of etched it before parking i think this lessened the affect the HAZ has on the parked finish.
    in the past they showed up very crisply. might be a similar thing w/ cold blue. i dont find it necassary w/ hot blue.
    Longshot1 likes this.
    not taking new work

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    +1 Muriatic acid can be helpful to lightly etch the metal and seems to create a better surface for the cold blue etc.
    Be careful using or thinning it with water. It can burn you and the vapors are not good.
    It also removes chrome and zinc coatings but do not breathe the vapors. I use a respirator. Or use a fan in an open shop room.
    BR7.62 likes this.

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    good idea mentioning safety !
    you add acid to water not the other way around....
    not taking new work

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    Sounds like I picked a scab...but glad I wasn't the only skinned up one out here. I have several pieces of 1/8" copper cut to go in all the areas above lower rails, under upper rails and behind slab sides. Tricky areas are mag well and upper rails. I find myself doing a lot of telling myself "This is it, I am not welding any more." Then I mill/grind/sand/file and back to the welder. Next one I do I think I will do the bevel on mated parts from an inside out view. Back the outside with copper and stitch and move on the inside. Then go to the outside for cosmetics. I left the inside a little heavy right behind the feed ramps on this one instead of grinding all the weld back out. Tried to blend it but it is a shooter and I want it to be reliable. I will try the acid etch on the next one. I actually browned this one first with Express 2. BR I gotta show my ignorance...HAZ???
    Last edited by Longshot1; 04-24-2019 at 09:03 PM.

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    sorry, heat affected zone.
    you might also try not beveling as much or not at all, except for the thickest spots. i think your idea of beveling the inside instead sounds great.
    its not hard to penetrate most of these thicknesses.
    and its more filler material that way which is potentially more different alloy to be a different color or whatever when refinished.
    Longshot1 likes this.
    not taking new work

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    Must have been getting late. My mind was stuck in the finishing rut and was trying to relate haz with type of process or chemical being used. Your comments are getting through much clearer this morning. I agree the challenge is to get any finish that actually penetrates the substrate and doesn't cover to look even. The weld just looks different from the adjacent parent metal which looks different from patch pieces. I shake my head every time I open a kit and see that perfectly good piece whacked up by a torch.

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    I would like to have a reweld myself. But not found any. Love to get a couple milled ones and a old Uzi one.

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    From experience seeing a couple dozen different Milled Yugos as complete rifles, many do seem to have been refinished at some point.

    Most have very viable tooling marks or "grain" as well, that seem to be done with a large, circular tool, almost like a disc sander.

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    Stottman you are correct. Like they just lap the sides on a disc or use a large fly cutter type arrangement as final finish on a mill. Hard to replicate in the welded area. I tried on this one. It was large radius circular marks on one side and virtually vertical marks on the other. Next one I think I will smooth the entire finish. Might not be perfectly original but it would please me. I think I will do a stamped and painted Hungarian next. Have a big old M64 with cosmo dripping off of it!!! Need a break from the welding. I did get a decent finish using the 44/40 cold blue. Will keep it oiled up good and put it away with oiled cotton gloves on. I am saving my pennies for an 80% milled receiver. Would like to build one.

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    I’d do this to duplicate the factory swirl marks.

    Practice on some two inch flat or sheet metal
    Clamp down a fence / strait edge ... angle iron.
    80 grit soft pad on your on your grinder .... and perfect dragging it across consistently in one pass letting the edge obviously drag on the fence.

    Then with the sides of the receiver sanded smooth down to probably at least 180 set up and do the same on it ... possibly may need to use 36 grit.

    This might actually help hide the welds
    Last edited by Mr Nobody; 04-27-2019 at 07:58 AM.

 

 
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