AK & Related Rifles, AKBuilds, Gunsmithing

How to Install a Flat’s Lower Receiver Rails So They Align With The Front Trunnion

I heat treat the lower rails before I install them.  The best way I found to align the lower rails in a flat so they were both parallel with the upper rail and aligned with the trunnion was to use a drill bits of the proper size to locate the lower rail and I would then clamp the lower rail in place prior to spot welding.  This is one of those things where you want to check and double-check prior to and after each weld to make sure nothing shifted on you.

I use a Harbor Freight #45689 115 Volt spot welder with AK-Builder upper replacement tong and also tips.  It’s lasted me through quite a few builds over the years and is still going strong.  The tong makes it way easier to reach in and make the weld and the tips make the spot weld look a lot more like the real ones.  I have had to replace the tips once so far, just FYI.  You need to keep them clean to be most effective.

For beginners, there is no way to tell you how long to clamp and trigger the current for – many factors can affect how long it takes to heat the steel up enough for the two pieces of sheet metal to weld together.  You need to practice and you’ll notice the color, sound of the welder. the amount of time it takes to get a good weld and especially the feel of the clamps as they come together during the weld.  With practice you’ll feel when you have a good weld especially but it all adds up but you need to actually do it to learn.

Get scrap metal of about the same thickness to practice with.  AKM receivers are 1mm thick.  18 gauge is 1.02mm so it is good to practice with and old scrap receiver stubs are another.  With your first practice weld, go long and let the pieces really melt together so you can see.  You want to burn a hole to understand how long it takes, the sound and the feel of the tongs.  Then practice with less amounts of time until you find the sweet spot.  These welds should be pretty strong and not pull apart easy.  I do more spot welds than most and some guys look at photos of the rifle they are building and try to approximate the count and location, which is just fine.  One thing, if you do heat treat your rails before hand like I do, be careful you do not get the tongs up against the ejector and ruin the heat treat.  I’ve done it and the tell tale sign is that the ejector will be discolored from the heat.  If you do make this mistake you will need to heat treat the tip while it is in the receiver or else it will definitely peen over and be deformed in its softened state.  By the way, the steel should be relatively clean also and not have tons of grease or other contaminants on it either that might inhibit a good weld.

Just double check alignment very carefully before you spot weld and also that your welder’s tong does not get against the ejector and ruin the heat treat – assuming you did that before installation.

I hope this helps you out!

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AK & Related Rifles, Gunsmithing

Converting a Milled M70 Front End for a Sheet Metal Receiver Using Screws

Let me open this article with a comment for people new to building AKs – the best proven method is to use rivets.  The Soviets did a lot of testing and the best mechanical join of the forged trunnions to sheet metal was a mechanical rivet.  To this day, all commercial and military AKs are built using rivets.  In my journeys, I have built AKs using welds, screws and rivets – all have pros and cons.  What would I build an AK with that I care about?  The answer is easy – rivets.  This blog post documents my building a prototype using screws.  Has it held up to casual non-military non-full-auto use?  Yes.  What would I recommend to you to build your AK?  The answer is rivets.

In a previous post I described taking a milled stub and welding it to a sheet metal receiver.  Another approach is to drill, tape and use alloy screws.  So, let’s talk about that a bit.  I did this build back in 2010 also.  I actually still have the rifle and it’s one of my most reliable AKs.  It takes about any ammo I stuff in it and I don’t recall ever having any issues.

For those of you who are wondering why I didn’t do rivets – I was bored and wanted to try something different plus this is a range gun and not something mission critical.  Here we are 7 years later and it’s still doing fine – no cracks, no loose screws … but it isn’t stressed either.  When in doubt, do rivets or a milled gun.

Also, bear in mind that the front trunnion was made from the milled receiver stub so screws made it real easy.

In terms of this build, I milled the trunnion down the same as I did for the weld build.   I used my Hungarian AMD trunnion as an approximate guide for locating the holes and used two #10 screws for the front top and a 1/4″ for the rear.  In both cases, I opted for national fine.  10-32 and 1/4-28.  So, for 10-32, I used a #21 drill bit to make the hole  and for the 1/4-28, I used a #3.

For drill locating and drilling the receiver holes, I used the AK-Builder trunnion rivet locating jig.  You just put the trunnion on the jig, locate the hole, slide the receiver on and drill the hole.

Now for tapping, being square is a good idea.  I squared my table to the drill press’s chuck and used it to hold the tap.  I use Tap Magic cutting fluid to lubricate everything.

For the screws, I used alloy button heads and secured them with red thread locker.  I reached in with a Dremel and ground down protruding screws.

So there’s the front.  I used an air riveter to do the trigger guard.

End Result

Here’s a link to the AK-Builder Trunnion Hole Jig.

 

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Blades and Edged Weapons Including Khukuris

Restoring a Giant 24″ Hog Splitter

Everyone needs a hobby.  I guess mine is creating or fixing things in my own way.  Back in 2014, I bought an absolutely massive beat to hell 24-1/2″ hog splitter off eBay.  This thing was absolutely a diamond in the rough.  Clearly it had been used very heavily – probably for decades – yet there was an amazing design in that beat up cleaver as well.  First off, the blade was almost a half inch thick and it weighed about five pounds.  Back in the days before machinery, you need mass to butcher big animals and this was (and still is) the most massive cleaver I have personally worked with – imagine a baseball bat with one hell of a heavy end is what it boils down to.

In the eBay listing, the seller was up front – this thing was on its last leg.  The wood was all busted up, dirty as heck and the blade was loose.  Of course, I had to buy it!  Here’s what it looked like when it arrived.  Why I did not get an overall photo at the start, I do not know.

There were no maker’s marks anywhere but it was too professionally done to have been a village blacksmith.  I still wonder who made this as I would love to track down more of them.  If you have one, or find one, and are interested in potentially parting with it, let me know.  I’d even be happy with just the giant blade.

Getting back to the story, I had to look it over and take stock.  This thing was stunningly heavy and the wood was busted up because it was thin and hollow.

There had to be more than what I was seeing so I broke the frozen on nut and pulled the handle off.  Wow.  There was the largest rat tail tang I had ever seen – and still haven’t seen one bigger!!  That’s how they spread the load.  What an interesting design.

Now, the wood totally intrigued me.  There was something about the color that caught my eye so I decided to fill it with glass reinforced epoxy.  Now not all epoxies are equal.  When you do structural work like this, you need an excellent shock resistant epoxy.  My go to epoxy for stuff like this is Acraglas liquid epoxy from Brownells.  

I but it in quart bulk containers and meter it out using syringes or a digital scale.  I use 5/32nds milled glass fibers and black dye to color it.  Fortunately, it’s the same dye I use for my plastics but you can either buy from Brownells or elsewhere.  So, over the course of several days, I mixed, poured and let it sit overnight as it takes Acraglas 24 hours to cure so this work is done in steps.

I used wood stripper to try and get all the grease and oils out of the handle plus I drilled open the end to fill it easier.  By the way, if you heat epoxy with a heat gun, it will get thinner and flow more readily until it cools.  Gentle warmth also accelerates curing of the epoxy but remember that just because epoxy feels dry to the touch does not mean it has fully cured – read the instructions for whatever brand you go with.

Next, I sanded, sanded and sanded.  The wood was very interesting – maybe a cherry or mahogany.  I’m not really sure.

The rat tang was HUGE.  I carefully marked where it was at and drilled holes for two brass pins just to play it safe.  I’ve never had Acraglas let go from a clean prepped surface but never say never.  The pins are a cheap insurance for a giant blade like this.  I inserted the 3/16″ pins with epoxy and then added epoxy to all the imperfections followed by more sanding.  Notice how I blasted the pins before gluing?  Epoxy always, always, always does better on a rough surface.  Do not epoxy two shiny metal surfaces together and expect them to last – they probably will not.

Now this took my breath away.  I used a 50/50 combination of turpentine and boiled linseed oil (BLO), put it in a tank I have just for these big cleavers and let it sit for a few hours before I pulled it out.  The color blew me away.  Wow!!  I wiped it down and then applied additional coats of BLO to seal it.

My last steps were to acid etch the blade (click here for our guide to acid etching), seal everything with BLO and then make a blade guard.  Mission accomplished.

To protect the blade edge, not to mention protect other things from the edge, I made a protective cover out of 0.093 Kydex and 3/8″ shock (bungee) cord.

That bad boy weighed 5-1/4 pounds and was solid as a rock.  I keep looking for another one like it.  I never did find out where it was made but it sure was a stunner.  This is another project that part of me wishes I had kept it but it went to a very happy new owner shortly after I finished it.

3/4/2020 Update: This is still the most wicked restored cleaver I have done. The wood was simply gorgeous.

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.

The following is a real-time search of eBay using keywords that have worked for me in the past and I hope they help you find something (note a few odd items might show up just like any other search does):

AK & Related Rifles, Gunsmithing

How to Bullet Drop Test a Barrel?

Plenty of AK barrel have seen heavy use and some are pretty much sewer pipes at this point – blown out, dirty and most of the rifling a distant memory.  A quick way to check is to take a cartridge of the correct caliber, such as 7.62×39, and put it in the muzzle.  If it stops before the case hits, there is hope.  It the case hits or even goes into the muzzle, the barrel is pretty much history.

Pass:

 

Fail:

 

I’m not saying the barrel is perfect but it may still be useful.  I built both M70 stubs on their original barrels and they shot good enough – about 8-10″ – at 100 yards fired with iron sights with cheap ammo.  Still a fun rifle to shoot though.

If a barrel fails, I would definitely get a replacement and not even bother trying to use it but that’s just me.  I’ve known a few guys over the years that proudly built and fired sewer pipe rifles.

Blades and Edged Weapons Including Khukuris, Gunsmithing, Tools

Acid Etching Steel With Apple Cider Vinegar

2 Comments

Some folks have asked how I get the dull grey look on khukuris that I used to work on.  The answer is simple – apple cider vinegar straight from the grocery.  I’ve also experimented with various ratios of Prep-and-Etch, which contains Phosphoric Acid, and gotten a darker color but apple cider works remarkably well.  Apple cider vinegar contains 5-10% acetic acid (CH3COOH) depending on how it is made.  For example, I read that Heinz is about 5%.  My local store carries Spartan brand, which is their store brand, and it works just fine – again, this is apple cider vinegar from the grocery store.  

This process only works with steels that can rust.  For example a mild steel or high carbon.  It will not work on stainless, aluminum, etc.

Safety Notes:

I would recommend doing this outside or some place very well ventilated or else if the acetic acid condenses on metal surfaces in your shop/garage, it will cause rust.

Wear safety glasses and don’t goof around with the stuff.  I’ve never had a problem but probably need to say some kind of warning here.

Process:

  1. Clean the part and remove all oil and grease.  Either hose it down really well with brake cleaner or soak it in acetone.  Any oil, even from your skin, will mess you up.  
  2. Abrasive blast the part – I use “The Original Black Beauty” media that I get at my local farm supply store.  It’s made from coal slag and is fairly environmentally friendly.  It does break down quick so if you use your blast cabinet a lot, be prepared to clean it out and add new media when performance starts to suffer.  Blasting will get you a really nice uniform surface color.  I suppose you could try sanding or wire brushing but blasting has worked the best for me and is all I do now.  My only recommendation is not to use sand because as it breaks down it creates a fine dust that will never come out of your lungs – read that as “bad”.  I do use a blast cabinet with a vacuum to get rid of dust, you could do this outside with a hand blaster or tank blaster and dust mask if you needed to.  I wear a hood when blasting outside as the media goes everywhere.  Just protect yourself is the bottom line.
  3. Wear rubber gloves and clean the part again – the gloves are to keep oils from your skin from contaminating the part and preventing etching.  Cleanliness is critical.
  4. Put the part in cider that is at least 70 degrees.  I like 100-150.  If it is too cold the reaction slows waaaaay down.  I don’t like to get it super hot or boil it as you lose a ton of cider with no real benefit.  I have done this in everything from stainless steel containers to plastic containers and even plastic trays used for wallpaper with halogen lights warming it up.  In general the colder the cider the slower the etching and the hotter the cider the faster the etching bearing in mind you will have the cider evaporating faster.
    Note:  If you do not see bubbles coming off the part then either the solution is too cold (especially on cold days under 70F), the part is not clean or ready (so clean and blast it) or the cider too weak.  I’ve never had an issue with weak cider – always the first two.
  5. Submerge the part in the acid and let it sit for 15-30 minutes.  It’s not a strong acid so there’s no rush.  Just check the part and stop at the color you want. The warmer the water and the part, the faster the reaction and vice versa.
  6. Rinse with hot water
  7. Rub down with WD40 and steel wool to get the loose particles off
  8. Then I like to seal it with boiled linseed oil (BLO).  Some of you may know BLO for woodworking but it is an old school rust inhibitor.  If you don’t want BLO, then thoroughly oil your part.

I like the results.  No real harmful chemicals are used, it’s cheap and looks great.

3/4/2020 Update: I recently did some blog posts on building a cost effective digitally controlled heat tank from PVC pipe that is perfect for acid etching – click here for that one. I’m also using a ferric chloride and apple cider etching solution now – click here for that one.

Photos:

The light brown solution is just apple cider.  If it is darker, it was 25-50% Prep-and-Etch + the vinegar.

Use whatever container works. These were from a bunch of zip ties I bought once.
You can see the abraded surface from the abrasive blaster. You can acid etch without this step but I find doing this first really makes for a good finish plus all the tiny nooks and crannies really let the BLO grab hold.
This one is getting ready to go it. I use WD40 when done to remove the water – it literally means “Water Displacement” forumula 40 and excels at that.
You will see lots of little bubbles. I go by the color of the etched steel more than I do the degree of fizzing or time.
These two have already gone through the process.
I like the post apocalyptic look it gives.
This giant cleaver was acid etched and then sealed with BLO.
Another angle of the big “splitter”. The blade is over a 1/2″ thick!
Another cleaver.

Abrasive Blasting

You can usually get a coal slag blast media very, very cheap from farm stores.  Check there first because off Amazon you are paying a pretty penny for shipping whether they bury it in the item’s price or call it out separate.  I think I pay $7-9 per 25# bag at Family Farm and Home.

This is the actual product I use:  http://www.blackbeautyabrasives.com/products/black-beauty-original-abrasives.php

Now for the blasting, you have tons of options – hand blaster for small work, siphon blaster, pressurized tank or cabinets.  It all depends on how much blasting you plan to do.  I started out with a siphon blaster – dirt cheap but very slow.  I then got a tank and it was very fast and portable but media went everywhere.  I still have that for working on cars and big parts.  However, for my grips, gun parts and knives, I use my blast cabinet.  I have a Cyclone brand large bench unit and am relatively happy.  If I had it to do over, I would have gotten a free standing unit with a bigger and deeper hopper so I’m not constantly hitting the side or moving media around by hand.  I have a foot control pedal and that really helps plus it gets a the pneumatics out of the cabinet where they would normally be subject to abrasive dust and wear.

Cyclone Manufacturing
http://www.cycloneblasters.com/

My pressurized tank blaster is a Harbor Freight unit.  It’s held up relatively fine other than my constantly wearing out valves and tips.  The tank itself is just fine.
http://www.harborfreight.com/40-lb-pressurized-abrasive-blaster-68992.html

Summary

Acid etching is easy and rewarding. I like using BLO to seal things partly because of the color it imparts.

I hope this gives you some ideas!

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.

AK & Related Rifles, Gunsmithing

Converting a milled M70 receiver stub to a stamped receiver front trunnion using plug welds

I miss building AKs – I never have the time any more.  At rate, some years back I wound up with two Yugo M70 front milled stubs, and then decided to convert the rifle to a stamped receiver because I liked working with AK-Builder flats.  So, in the spirit of trying something new, I decided to convert a stub to a trunnion and plug weld it in place vs. trying to machine the rivet seats inside.

Yes, I’ve heard tons of people say not to weld them together and that rivets are better.  Yes, rivets are better and I have done many of them.  Have I ever had problems with a weld build where I filled the holes I drilled with plugs, stayed away from the locking lugs and was careful with the heat?  No, I have not had any problems.  I have an AMD-65 with tons of rounds through it that still runs fine.  My thinking is that I am not firing full auto, not using grenades, don’t use this in combat … I’m not really stressing it.  What would I use for a reliable build vs. a test like this?  I’d use rivets.

Why the big caveat in the previous paragraph – I get one or two emails a year from a purist telling me that what I did was evil, that I am a clueless half-wit, etc. Folks, innovation happens by trying new things. I have built more AKs than most – using rivets mainly because they do work best. There are a ton of reasons why rivets are best for joining forged blocks to sheet metal.

In terms of welds, do I understand the risk of destroying the heat treat in the locking lug area, the risk of causing embrittlement around the plug welds, that the Soviets explored this and dropped the idea due to cracking? Yes, I do and tried it anyway because I wanted to explore how to compensate. So, don’t send me hate mail me because I will not bother responding. When I first shared this, three guys immediately sent me hate mails and unfriended me – I did not lose sleep about it.

If you want to try and experiment, go for it. Should you do this with an AK build that you want to be historically accurate or plan to use heavily perhaps even under full auto, then the answer is “no – don’t do it”.

The build I am sharing photos of was done in 2009.  I found the photos and thought you might like to see them.

Here are the front stubs.

When you look at the front stub, you can see readily hiw it could become a trunnion.

Here’s a Hungarian AMD trunnion next to it.

Here are the stubs from a couple of angles.  I already used my bandsaw to cut the top one

Ok, time to make some chips.  It’s secured an I’m milling the OD under the top shelf of the trunnion that sticks out over the receiver:

I didn’t have anything to cut the slot with for my mill so I clamped a straight edge and then ran a Dremel wheel down it over and over until I got the depth and width needed for the stamped receiver to to slide into:

My theory was that by drilling holes and filling them via plug welds that I could lock the receiver into place.  Thus, I drilled holes for the plug welds both in the stamped receiver and into the newly made trunnion:

The plug welds were done with a Harbor Freight 220V MIG running ArCo2 gas and .030 wire.  I let it cool down after each weld and was careful not to pour on a ton of heat.  Notice the relatively big weld area to distribute the load.

I then sanded it all down with a flap sander.  The back was just a regular M72 rear trunnion that I found at R-Guns. I never had problems with cracking, etc.  The experiment seemed to work for a casual use semi-automatic rifle.

That’s all I have as far as photos go.  I hope maybe it gives you some ideas.

Writing this makes me wish I had time to build another AK but it’s back to our grips and handguards 🙂

Note, I have to buy all of my parts – nothing here was paid for by sponsors, etc. I do make a small amount if you click on an ad and buy something but that is it. You’re getting my real opinion on stuff.

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.

Flashlights and Lasers, Shooting in General

How to Safely Save on CR123A Batteries for Your Tactical Lights and Lasers

The CR123A battery is very common in tactical lights and lasers these days.  I have a ton of lights that use them and think they are a great battery type and do not have to cost fortune to operate.  There are two tips I want to pass along so you can safely save money.  Now you might be wondering why I put it that way and it’s simple – CR123A batteries are lithium and when they are discharged deeply and rapidly, heat is generated and unless the batteries are properly made, they can literally catch on fire or even explode.  Now this tends to happen with dirt cheap batteries / no-name knock-offs and when they are used improperly such as mixing new and used batteries, types of batteries or trying to recharge batteries that were not designed to be.

Useless trivia for you:  CR123A is a code.  CR = cylindrical.  The 123 means it’s size is a ratio 1×2/3rds its length of “A” cell.  Put it together and you get CR123A.

So, to be safe, only use name brand batteries and change them all at a time.  For example, if a light or laser is going dim them change all the batteries at once with new cells of the proper type and I would even recommend from the same manufacturer.  I would also recommend only sticking with name brands from reputable sources.  Yes, cheap knock-offs show up on eBay and Amazon so be very suspicious of deals that seem to good to be true.

In terms of purchasing the batteries, do not go into a retail store and buy a retail package of one or two batteries in the camera department.  You will pay through the nose.  Instead, go to Amazon and buy Panasonic, Surefire, Streamlight or Energizer batteries in bulk packs – usually they are at least 12 batteries.  You are looking for new fresh batteries that aren’t being sold cheap because they are near end-of-life.  Lithiums last, or have a “shelf life” of, about 10 years from when they are made.  That also means that you can afford to buy a bunch at once as they are going to last quite a while provided they are relatively new when you buy them.

Why am I not recommending no-name batteries?  Simple – there is a reason why some of the tactical product companies say they will only warrant their products if you use certain brands – problems do happen.  At a minimum, you may not get as long of life from a cheap battery built compared to something from a reputable firm.  There are good niche batteries out there, but I am going to stick with the big brands.

I am careful to read the description and reviews before I buy on Amazon as there are unethical sellers out there.  Look for listings with lots of 4 and 5 star reviews – the more the better.  Beware of listings with few reviews of any type – no telling how long they will last.  Read the reviews – are they fresh batteries, counterfeits, or good to go?

Here are some examples to help you get started and I listed them in the order of what I would select – meaning my first choice would be the Surefire batteries [click here] and the second are the Streamlights [click here].

If you just search for CR123A batteries on Amazon, you will see a ton of products for sale with different brands, quantities and so forth.  Shop smart and you’ll save big time.  I hope this helps you out some.  I’ll list more from Amazon at the bottom of the post if you want to scroll down.

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.

Uncategorized

Nathan’s Cool M92

This is Nathan’s cool M92 SBR.  I sure like the side folder and it has our M92 handguard set.  Very clean lines!!

 

When Strength and Quality Matter Most