Gunsmithing: Heat treating an AK receiver (Gunworks)

[@herbender]

Just a little tip, if you put a piece of paper or charcoal in the stainless envelope together with the piece you are going to harden the paper or charcoal will burn and consume all the residual oxigen left in the envelope.

[@parkerxxxxxx]

Color case hardening always looks unique. I've seen guys dress up their AK's with nice wood, but I've never seen one with CCH. And that sounds like something worth trying, just for giggles. I'll bet viewers would like it as well. I always enjoy your videos. Thanks again.

[@downeastgunworks]

Yep. I grew up in western NC until I joined the USMC. I was gone for quite a few years. I moved around the country a bit later as a civilian. I worked as a horse wrangler on a few ranches, and even worked for the US Park Service a while.I moved to Maine about 8 years ago. Now I'm a gunsmith.

[@downeastgunworks]

This is not my usual quality video. It was filmed entirely in segments using an iPad. It was also edited in the same iPad, and been sitting in the memory until today when I decided to try to post it.

[@downeastgunworks]

Yours will be the first finished product as soon as we get back from location in Florida in about a week. if you recall, I did mention the new TV series and how often I'm out of the shop running around locations. It's a pain in the butt, and I have a hard time keeping track of all the projects in the shop, but since I have a new helper now, things will get much smoother. PLUS -- I got all winter off to play catch up in the shop.

[@downeastgunworks]

Well the last sheet of stainless steel I had on my roll wasn't quite big enough to wrap it like I normally do. As expensive as that stuff is, I hate to toss out even small scraps. It was barely big enough for the video. ALSO, the day I filmed this, I forgot my regular camera at home. I just bought an iPad and decided to see if it would take quality videos. NOPE. But this video was a response to questions about how I harden an AK receiver for a quality build.

[@copperhead2534]

Follow TheDarkKnightBuilds instructions with slight mods for a properly treated 4130 AK BUILDER rec. Order ATP anti scale compound/paste from Brownells. Drill all holes, properly dimple where required, and install/spot weld and drill rails on rec. Coat rec in and out w/ATP anti scale paste compound. Anneal first for minimized warping and full stress relief by placing rec in a cold oven, then ramping to 1625 degree F, turn off oven and allow to slowly cool in oven overnight. Next day ramp up oven from cold with annealed rec inside to 1600 degree F. Do not hold/soak, Quench in salt brine per TheDarkKnightBuilds instructions, and follow with his temper/draw instructions. You end up with a straight rec with a Rockwell 41 to 43 target hardness.

[@downeastgunworks]

Yes Sir, if you 've seen the commercials on that channel for that network.... yep it was me. The episodes will air by the first week of December. I ain't supposed to say much about that whole deal due to a confidentiality clause. But if you like antique guns, machine guns, cannons ( real ones ) and lot so explosions.... then you might like the show. Antique armor, swords, wheel locks that are 400 years old.... etc.

[@downeastgunworks]

yes Sir, I usually fold it up like that. But this was my last piece of steel foil and didn't want to waste it. It was barely big enough to use in the video. Maybe I should refilm this one again later using the better camera, and the larger piece of foil. I had so many questions about heat treating receivers, I decided to answer in a video about it.

[@Mel64d]

I work in Tool & Die (20+ years) and heat treat and draw all my receivers. Then check with a Rockwell Hardness Tester. My receivers come out around 42 Rc to 45 Rc. I tried your method since I have tons of the same foil laying around. The receiver was all over the place as hardness goes, and was soft enough that I might as well just not have treated it. I never put a receiver in a hot furnace (warp big time) I let the receiver come up to temp with the furnace, during stress relieving, heat treatment, and drawing. Not worried about scale build up since I sand blast and parkerize all my receivers. Not preaching to you, just saying.

[@DieselRamcharger]

what are your soak temps and times? for hardening and drawing back? do you build a wall of firebrick around the receiver to stop the direct heat from the coils from warping? {or is that b.s.?}

[@Mel64d]

@Diesel Yes I build a wall of fire bricks. I stress relive the receiver at 750 for 2 hours, then let the oven cool. I then put the receiver in the oven and bring it up to 1600, do not hold at that temp, I pull it and dunk it in quenching oil. Then I let the oven cool back down then put it back in and bring the oven up to 750 and soak for 45 minutes. ...a little tip....do not spot weld the rails in until you have fully heat treated the receiver. Lay it upside down (on the top rails) and do the heat treat. If you heat it up with the rails installed that area is much thicker and will take heat and cool down much differently than just the receiver alone. This will result in a slight bow inward, so if you do the spot weld last you will have a nice non warped receiver. The countries that build them today do this exact same method of spot welding the rails last.

[@DieselRamcharger]

***** thank you for the detailed response. Your method is basically what i have devising in my head, its nice to hear someone actually confirm i am on the right track. I haven't been in the shipyard in quite a while, need a kickstart for the mind. Do you heat treat the entire rail before spot welding them in? would it be acceptable to heat treat everything as a batch, only not welded of course. i built my oven from an old clay kiln and a PID system with ceramic thermocouples. interested to see how it works out on a receiver. Has to be better than the torch "spot heat treating" method you see preached on the boards.

[@Mel64d]

You're welcome. This is the way I have been doing it, and it has worked out pretty good so far. I am by no means an "expert" but I have done several of these heat treatments on ak receivers. I work in Tool and Die and have access to a heat treat oven. Not really cheating just using what I have. The Kiln should work out well for you. If you go to "The dark Knight Builds" on KZbin, he uses a kiln to heat treat his receivers. This is where I got the temps and times from for my builds. Well I guess I should answer the "rails " question. You can place them in the oven at the same time as the receiver but they are thicker and will need a little more time to fully heat all the way thru. I just use a torch and heat them up to glowing and then dunk them in quenching oil. If you are going to use motor oil, use old used motor oil, it is full of carbon (the reason it turns black) and is close to the same thing as quenching oil. You will need to heat the rails after quenching with a torch or oven again but only until they are a bluish color, then just let them cool on their own no quenching. I also have access to a Rockwell hardness tester, so I can get everything just like or as close to "factory" specs.

[@DieselRamcharger]

i don't think anyone in our shop formally knows how to use the rockwell tester. Leaving me free to tinker and toil with it at my will. I have seen the dark knight builds, i have coincidentally the same basic setup as him. Built of whats cheap and available.. Plenty of used oil around here, i keep all the oil out of my diesel in hopes of one day finishing my mini refinery/pyrolysis plant. Im going to get back to building soon. Things weren't turning out as i liked, so instead of burning up hard to get parts i paused to tool up. i went a little over board…but the home shop is just about their :)

[@murphysmuskets]

Ahhh nothing like the smell of burning steel! Nice video Jim! Good to see you getting back to work!

[@downeastgunworks]

Actually I had that very idea in mind. if you want one built and CCH let me know. It would look "classy".

[@wayneuber]

Just position the reciever diagnally across your stainless steel, roll it once and fold the edges (ears) over the center, then finish with hone more roll across the center. This probably sounds more complex than it is but you won't have to worry about cutting your hands and it seals whatever you put in the center from outside air. Good video!

[@briancbk]

the foil is keeping the quench solution from cooling the receiver immediately, and will affect the final hardness. If the receiver can not contact the water, you will not achieve full hardness. the foil will allow steam to build up between the two surfaces, allowing the metal to cool slower. Have you had one tested for hardness? I understand what you mean about the discoloration, but not sure this is the way to prevent it.

[@downeastgunworks]

If you bend a flat and leave the steel soft, you will eventually end up with premature wear on the gun. The axis pin holes for the trigger and hammer will start to become elongated. Once these components are out of alignment, the gun will have malfunctions. The rails become worn and the bolt / carrier do not track properly.

[@rjr1954]

Like video straight to point and how to heat treat

[@downeastgunworks]

I've been thinking of CCH one of these AK receivers to see if it'll look nice or not. MAYBE with some nice wood for a stock ?

[@downeastgunworks]

Quenching in salt water results in a harder surface on the steel.

[@agoogleaccount2861]

A little cold bluing added to the salt water will give a nice bluing authentic to some original 70s ak finishes

[@STBRetired1]

I'm going to do some more research but I could swear that I've run across someplace that said NOT to spot weld the rails on BEFORE heat treating because it can cause warping in the un-heattreated receiver.

[@jeffreyMagnum460]

Fold it up into a pouch then fold the end shut I also put some paper in the pouch to burn off any oxygen in the pouch.

[@mach1mustang1971]

OMG i thought that was you...we went to high school together at East Burke...this is just too wild...so glad you are doing well Jim...my name is Scott Cassidy...we graduated together...hope to talk to you more some time...take care!

[@mds19238]

Liked the video and the straight forward approach, thank you.

[@DocArthurTX]

How do you prevent warping in a 1.2 mm receiver?

[@downeastgunworks]

Correct. If this is a gun you build for yourself only, there is no need for a serial number.

[@cat9x]

another great video from a GREAT gunsmith!

[@zanesttc]

clear, informative and entertaining. this why i subscribed, thank you and keep it up

[@newdefsys]

Nice work. Would adding burl walnut furniture to a case hardened AK be over the top ? Sounds like it might be awesome, don't know if it would sell though. It would still better looking than one of those gold plated AK's from Iraq, those things are an eyesore.

[@bigbearfuzzums7027]

Sounds pimp as hell do it!

[@mach1mustang1971]

great video Jim...i grew up with a guy named jim green that looks a lot like you in NC...just wondering if you might have lived down this way when you were younger...take care and thanks for posting all the great vids...

[@chitownbangin]

Great video.

[@wayneuber]

Jim, is there a reason you don't wrap the receiver like a sub-sandwich (make a point of watching the experienced help at a Subway shop)?

[@uncletom1986]

do you just throw it in at about max temp then let the piece get up to temp and quench or do you stress relieve for a couple hours at about 700 then let it cool then bring it up to bout 1600 and quench then draw the temper back?

[@gman77gas]

what is the % carbon in the steel you are heat treating. What is the end result of rhe heat treat in Rockwell scale? do you check the hardness with a rockwell tester?

[@oldgoat1890]

Anybody know what kind of steel the sheet metal is made of?

[@Doctorchops]

Any chance you sell AK receivers? I'm gonna be doing a Polish Underfolder build here pretty soon.. I was planning on buying a NoDak but I don't have the cash for that right now, so I was planning on doing it from a flat, but I've watched enough of your videos to know you do good work.. much rather buy one of yours if you sell 'em.

[@LanfermanInc]

What do you charge for heat treating?

[@khmerViper]

How do you make the barrel hear treated? That make it not heat as fast, when Fireing? AR-15

[@farhanansari5125]

Hello sir .. can you help me about mag spring .. Mag feeding problem Can I heat treat the spring ? It will fix my mag spring problem?

[@czechyour66]

Very cool mod, im hoping to do something diff with an AK soon :)

[@farzanaakther4197]

how to make ak 47 trunnion ? please show

[@lisanelson2636]

Living the dream

[@bigbearfuzzums7027]

Hey how'd how's it going Jim!

[@downeastgunworks]

I can't say WHAT the name of it will be due to confidentiality agreements. But keep your eyes peeled on Nat Geo.

[@carryitaround]

did you heat treat your mosin receivers after machining them?

[@parkerxxxxxx]

Great video again. Okay, I have to ask; have you ever case-colored one of those receivers? It would be "different." Just curious. Thanks

[@RowleyEric]

what network will it be on jim?

[@mcyclonegt]

i was wondering the same thing. did you ever find an answer?

[@checkpoint3260]

don't you still got to treat it at 475-700 for a hour or so and let it cool?

[@jdmcommute]

Awesome! Thanks Jim!

[@cabinfever7262]

Very interesting video, ty.

[@drewcoble4226]

whould you need to do this to a full auto ak

[@Doctorchops]

And if not thanks for the good video.. I'll most likely end up doing exactly this if I go from a flat.

[@This_guy_over_here]

Great video, however I do have a question. If I plan to weld the trunnions and cross bar in place as opposed to riveting on an AK build, would I want to heat treat the receiver completely then do the welding? Or would that destroy the hardening accomplished through the heat treating process. Sorry if it sounds like a dumb question, but I honestly have little background in metal working.

[@PilotDamian]

Nice video and like the dog too :)

[@GunRagDave]

Why salt water?

[@downeastgunworks]

I been busy all summer filming episodes for a new TV series coming out in about a month. I ain't allowed to divulge much about it yet. Suffice it to say the show's about guns. Pretty soon, everyone will get SICK of seeing me so much.

[@ivannieves5708]

3 pounds of salt and 5 gallons of water. How do you make a smaller batch of brine solution?

[@robertarthurs328]

You don't sound like you're from Maine lol

[@downeastgunworks]

drop me an email muleequestrian at yahoo. I'll PM a phone number.