[ProfessorPlum]

I’ve been traveling for work projects recently. I’ll probably keep the same pace for the foreseeable future, so I’ll be here off and on. In the last couple months I’ve taken a few photo sets of stocks but the quality isn't what I wanted for the post. Next I’ll probably do an article on the classic ’68-’69 saw-cuts that got many of us into the game. For now, I’ve promised to share my first build I did back in 2016. By that time, I’d had my first pair of kits for four years, and I was slowly collecting parts for the build. That’s why I’ve joked I’ll be lucky to finish my Sauer kits in this decade! I took these photos and some shaky video for my records, but together the best of them do give a decent idea as to how things came together.

Demilling, receiver prep, and front trunnion install

There’s not much to say about the demil process that hasn’t already been posted by others. The AK-Builder (AKB) triggerguard demil guide was helpful. Eventually I bought their other rivet drill guide too (the one shaped like a little hammer with holes through it). It has been quite handy. I drilled out the rivets with a 5/32” bit, using a much larger bit to effectively drill off the head itself. I used (and bent) several 1/8” and 5/32” punches to knock out the rivets. I recently purchased a set of short punches that might be able to get rivets moving without going sideways. I continue to have trouble from time to time knocking out long rivets. Throughout this process, I was a little rough on the receiver stubs since I had no intention of keeping them intact. A more careful process could preserve them.

For the barrel parts, I used an assortment of AKB tools and parts made by Robert Forbus (RF). One that does not show up in the photos is RF’s barrel disassembly plate – a steel bar with D-shaped cutouts sized to support barrel components as the barrel stubs are pressed out of them. I might have used a hack rig to remove the barrel component pins. I think I set the components on a Brownells hockey puck style bench block with a few drill bits here and there to level the part for pressing. By assembly time, I’d upgraded to RF’s barrel component block you’ll see in later photos.

With the parts all demilled and cleaned up, it was time to prepare the receiver and barrel. First, I used the AKB trunnion hole drilling fixture to transfer all the trunnion hole locations to the receiver by aligning the fixture to the drill press and then sliding the receiver in place to drill each hole. I sandblasted the receiver with whatever media was in use by the shop down the road. Next time I’ll follow Techno’s instructions for paint prep, which calls for 120-180 grit aluminum oxide. I used Brownells zinc Parkerizing solution and half-tanks on a makeshift burner setup. It seemed to work quite well following their instructions. The parts really bubble when they hit the solution, and the bubbles stop when it's done. The boiling water, hot detergent, and Parkerizing solution are seen on the grill. Not shown is a flowing cold water rinse tank – a garden hose in a roasting pan.

The first step of assembly proper was to dimple the countersunk front trunnion holes. I used the pricey AKB rivet tool for all riveting work. Watching rivets get squished in place nice and slowly using the press was quite rewarding, so I feel like I got my money's worth from entertainment alone. For the front trunnion, a dimpling base and flat-faced arm insert were used to depress metal of the receiver into the countersunk hole of the trunnion.

Since the flat insert was already installed on the arm, I started with the forward rivets. These are accessed through the bore of the front trunnion. These rivets are smashed flat to clear the barrel channel. They’re also completely obscured by the barrel if they turn out ugly.

The lower rivets are accessed through the magwell using the round-faced arm insert, which forms a nice domed head on the inside. I used AKB rivets, which I get discounted after buying the rivet tool.

 

[ProfessorPlum]

Rear trunnion and triggerguard

The rear trunnion work requires reconfiguration of the AKB rivet tool. A threaded assembly is tightened to secure the receiver. Tools are fed through the center of the threaded assembly. First, a pointed dimpling tool used on both sides in turn. A metric ½” wrench to tighten the assembly can be seen to the right. Pro-tip: don’t dimple the hole for the selector axle.

A long rivet is installed, and an alignment tool is placed to ensure the receiver is secured with the rivet centered in the tool.

After aligning the assembly, a cupped tool is used to form the domed head. It looks like I had a mismatch of material so the formed domes don’t quite match the factory heads. The AK-74 uses a flat head for the rearmost rivet. I’m undecided on how to form that one on my current build, but I might simply form it as a dome and file it flat. All but the earliest AK-74s have forked rear trunnions that use short rivets. These are installed similarly to the lower rivets of the front trunnion, but due to shorter clearance, the rivet tool has a special arm just for that task.

There are also AKB parts for this tool used to form the rivets that secure an optics rail. This process is “backwards” from the previous examples since the round factory heads are within the receiver, and the flat head is formed outside the receiver. I’ll give that a try on the ‘88 AK-74N project I’ll hopefully resume soon.

Now onto the next single-purpose tool. The AKB triggerguard jig holds the rivets in place and comes with some blocks used to smash the heads flat within the receiver. One block is grooved to clear the receiver center support while pressing down on a pad that forms all four front triggerguard rivets at once (more on this in a second). The grooved block is also used to smash the rear triggerguard rivet.

My first attempt at the front rivets did not properly form them. Having a model, or at least photos of parts before demilling can be a helpful reference. Compared to the original rivets, the front four needed to be pressed again. The pad had to be shifted left and right between pressings to flatten them evenly since it does not cover the whole surface in one pressing. This was the one process that seemed to push the 10-ton Harbor Freight to the limits, but I was satisfied with the final result.

With the riveting complete, basic functions could be tested. Some tests were actually done earlier in the process, like ensuring fit of magazines before the triggerguard and mag catch were installed. Installing the bolt, carrier, and recoil rod allows you to produce the familiar “klack-klack” used to call Kalashnikitties. Since this is was a typical refurb kit from R-Guns, you never know what you’ll find. Here is a lined-out on non-matching recoil rod and even a non-matching electropenciled later-model cast selector.

 

[ProfessorPlum]

Barrel install

I mis-identified the original AKM barrel finish under the paint as bluing. I needed an excuse to level up my rust bluing skills anyway, so I used the Pilkington rust bluing solution and a pair of carding brushes – a fancy name for stainless wire brushes when used to remove the crusty oxide remaining after the boiling process. The best one for the job was a big round one from Brownells that I chucked into the drill press.

I blued the barrel to experiment with my technique, but then I used my micrometer and telescoping gauges to measure all the barrel component bores and associated barrel journals. Using a “shoeshine” motion with a strip of ~120 grit emery cloth, I reduced the barrel journal diameters to obtain acceptable interference fit at the trunnion and each component. Then I rust-blued these sanded areas to see how well I could blend. The rust bluing process seems quite forgiving. Next time, however, I’ll Parkerize the barrel with the receiver. The original Russian preparation was apparently a phosphating primer, so maybe something like K-Phos would be a better approximation of the original process.

I used a couple rods from McMaster Carr to align all barrel components by eye. They are 3’ sections of drill rod in 0.2010” and 0.1563” diameter; I must have had a reason for selecting those sizes, but I sure don’t remember what that was. I’ve used similar alignment techniques on other firearms with threaded barrel assemblies to ensure I’m clocked-in within torque specs. It’s not very scientific, but it hasn’t let me down yet. I tried to shove the barrel into the trunnion by hand – just enough to bite – and using the pistol grip, I held the assembly at arm’s length to check for offset of the alignment rods. Over a few iterations, I make an adjustment and retest until the rods are parallel. This same basic technique was used for all other barrel components as well.

I used the AKB barrel press jig and a 1-cent crown protector to force the barrel into the trunnion. From the photo it looks like I did apply some sort of lubricant – probably whatever was in an oil-can within reach. I had the headspace gauges right next to this operation and frequently tested using the bolt and a gauge after adjustments. Of course, the goal is to have the bolt close on the go gauge while not closing on the slightly longer no-go gauge. I didn’t bother to strip the bolt for these tests. I did retest using both the bolt and carrier whenever the assembly was removed from the press.

Unfortunately, my combination of press technique and interference fit caused a lot of jumping. With one pop of the press, I could jump from a way too long headspace to a way too short headspace. I used the RF barrel push back tool to reset. I can’t count the number of times I swapped between pushing the barrel in and out, jumping over the proper headspace each time. One technique that seemed to help, but might have just made me feel better was to apply a little hydraulic pressure, but then whack the press crossbar with a rubber mallet to try to cause smaller jumps. Eventually, I got the headspace on the tight side of the spectrum, just what I was hunting for.

The receiver was secured in the drill vise, elevated by parallels, left side up. With some cutting oil applied, a carbide size-I drill was used to drill halfway through the pin hole without damaging the hardened trunnion material. The receiver was reset in the vise, this time right side up. More cutting oil was applied and the same bit was used to drill the remainder of the channel. The bit was swapped with the 0.275” chucking reamer to finish the hole. The AKB barrel pin tool was used along with the press to install the pin from the right to left side. All pins were removed left to right and installed right to left. Because that’s how they are initially assembled, the right side pin heads have a tendency to “mushroom” slightly. Headspace was rechecked, and then I was off to the backwoods to test-fire what was essentially a long barreled single-shot pistol.

At this point, I’ll let you know that safety glasses had been used throughout pressing and hammering operations. A face shield was added for the test firing; maybe it’s overkill, but it is part of my process on this and other similar projects. I carried my headspace gauges with me to see if I could detect any barrel movement. Everything seemed fine, and the spent brass didn’t look unusual. So I took another few shots for science. I was surprised by the amount of force needed to extract the spent cases. It did not seem to be an excessive force, but I definitely couldn’t keep on target while extracting the spent cases.

 

[ProfessorPlum]

Barrel components

Apparently I used feeler gauges to help align the rear sight base between the trunnion ears – I don’t remember this so well. The RSB was pressed using RF barrel assembly tubes. When close to being in-place, the top cover was installed to ensure a good fit. The assembly was removed from the press and tested for fitment with the bolt carrier, recoil rod, and top cover. Everything was snug, so the next step was to secure the sight base flat in the vise, right side up, and drill through the pin hole using a size-22 bit. I pressed the pin using an RF ram fixture and the trusty bench block.

Next, INSTALL THE HANDGUARD RETAINER. The gas block was aligned using the drill rods, and the RF barrel assembly tubes were used again to press the block in place. The gas tube was used to gauge the proper distance for the gas block, which I continued to press until the fit was snug, but I was still able to remove and reinstall the tube with the latch open.

Installation of the front sight base was no different. The sight base was aligned using drill rods and pressed in place using the RF barrel assembly tubes. The tubes come with sections and a brass insert that are used together to locate the sight base the proper distance along the barrel.

To drill the pin holes square, I first secured the barrel in the horizontal groove of the vise. Then I rotated the barrel until the pad of the bayonet lug was square to the bit. I know I stole this idea from somewhere. A size-32 bit was used to drill the remaining pin holes.

A RF front sight and gas block pin plate was used as a sturdy base when pressing the pins. I had to locate the detent and spring before I could install the forwardmost pin. It might be that the rifle should be sighted-in before drilling and pinning the front sight base in case it is canted. I didn’t do this, but I might consider the procedure next time. Since my next build is an AK-74, perhaps I should sight in without using a muzzle device. I don’t know how much force the typical AK-74 brake receives with each shot and if there is any risk of it flying off the barrel.

 

[ProfessorPlum]

Gas port and US piston

An AKB long gas port bit was used with a hand drill to make the gas port. A brass rod was placed into the bore to protect from drilling into the other side of the barrel. This step was near disastrous. The process was actually so easy that I drilled much of the way through the brass rod before I checked my progress. I did not see any brass chips from the bit, and the angle made distances difficult to judge.

922r compliance: a heated topic with many opinions on how and weather to follow this regulation. I think we all would insist upon using a Russian trunnion, bolt, and carrier (3 foreign parts). I also prefer to use original magazines (3 more parts) and original furniture (so far totaling 9 foreign parts). With few exceptions, I also use original muzzle devices. Whether a barrel nut or thread protector is considered a muzzle device is open to interpretation, and I chose not to voice a strong opinion either way. Regardless, I’ve met my 10-piece limit on foreign parts, which means I use a US receiver, fire control group (hammer, trigger, and disconnector), gas piston, and barrel. If I had an original barreled AKM, you bet I’ll be using the original barrel. I prefer not to trade out another original part for a foreign made barrel since the AKB chrome-lined barrels so far are good enough for me. If I were building a 100-series rifle, I’d want to have a cold hammer forged barrel since that technology was in use by the AK assembly lines by that time. Some will state that a foreign barrel will result in a more valuable build. I won’t dispute this, but I’m not building to sell anyway.

The compliance parts I used included a Tapco G2 single hook fire control group. (I’m unsure what to use after I expend my last couple Tapco sets.) I also used an AKB gas piston. The piston removal can be tricky, but the install involves hammering metal on an anvil. The first step is to locate the slight discoloration of the retainer pin. I used a center punch to mark the location for drilling. I’ve forgotten any sizes I used, but my process was to gradually step up bit sizes until I separated the head of the pin on one side. I might have used that center drill visible in the background. I then used a punch to drive the pin out the other side. Take note of the gap between the piston flange and carrier; the piston can be untwisted using pliers or clamping it in a vise while the carrier is rotated.

The new piston must be drilled for the cross pin. The piston can be threaded into the carrier with the pin holes used to guide the drill bit from either side. I used this technique on a previous piston swap, but on this full build, I tried out the AKB piston drill jig, another single-purpose gadget. It guides the bit easier for a quick drilling operation, but it took me a bit longer to figure out the proper spacing. There is a degree of literal wiggle room in this procedure, but I think I got close to the original placement of the cross pin. The piston is threaded into place, and once the hole is aligned, the pin can be installed. Placing the assembly head-down on the vise anvil or other suitable surface, the head is formed on the other side of the pin by pounding away with a hammer until it conforms to the surface of the carrier. Then pound away at the original head until it also conforms to the carrier shape. Next, file both sides of the pin to blend it into the carrier. The original paint will be scraped off the area around the pin, but the carrier can be spot-painted after masking the piston.

 

[ProfessorPlum]

Paint and assembly

I can only assume I already had a long day before painting. My strategy was to mask the original components before hitting the surfaces with an aerosol degreaser, a trusty can of brake cleaner. Some of you already realize that this sequence of events would cause the adhesive of the tape to dissolve and run, which did happen, and it made a big mess.

I proceeded to clean up the mess in a kitchen sink using hot water and regular detergent as a degreaser.

Once dry, I masked the original-finish (or at least refurb-finished) parts again, and laid down my first coat – a nice rattle can of Rustoleum appliance epoxy. Before you cringe at my paint selection, this was a refurb after all, and it was before the days of the commercially available Russian paint, which I intend to use on my subsequent nicer builds. I kept adding light coats until the paint looked deep black and even.

I’m sure I wrote down the time and temperature somewhere, but suffice to say I cured the Rustoleum finish in a household oven. It was something like 20 minutes at 200°F, but it might have been a little hotter. I think I covered my tracks by baking some potatoes or a Totino’s pizza afterwards – a sacrifice to the great AK maker.

I’ll close with some photos of the final assembly. This is a rifle I’ve used for target shooting with family and for hauling through the woods on walks where I’m a little further from the house towards hog country and want more firepower than a pistol.

The handguards have typical markings of replacement furniture. The buttstock... I'm not sure. It could be a reshaped and refinished Izhmash. Oddly enough, it's the only RGuns stock I have that does not have a big slash-square mark on the right side, even though it is clearly not original. But for what it is, everything just seems right.

Please reply with your questions and comments. Even though there is so much text here, I have many more notes about the process that didn’t make it into the post. I’ll be glad to discuss any areas further or attempt to answer your build questions. Also, I look forward to constructive advice from other builders. I’m sure there are plenty of areas where I could improve.

pp

 

[scottyb]

I’ll take it.

Thumbs up for AK kitty.

Fantastic write up and darn good tutorial for any potential builder.

 

[KingDhruv]

I wish I could give an extra like for AK kitty. Great walkthrough of the process, after reading this I have more appreciation for builders.

 

[65cobra]

looks great, your work is impeccable!

 

[Commander Marnie]

Your cat! I love himb 🤗

 

[Vlado]

Is your cat electro penciled?

 

[ProfessorPlum]

Is your cat electro penciled?

Probably just hen-scratched. Weasel is an old frail thing now but still kicking somehow - always had a distinctive look with his slight underbite.

Thanks, guys, for the response. None of my build process is done in a hurry. I just have a few gadgets here and there that total well under the cost of a kit these days. I don't think I'm exaggerating that with a little patience, anybody can do this. The most precise aspect is setting the headspace, and we have inexpensive gauges to verify that to take any guesswork out of the picture. I could have taken a little more time to ensure front sight post alignment. It's fine this time, but next time I'll probably sight-in the rifle (adjusting the FSB as necessary) prior to pinning it just to be sure.

I don't plan on ever building from a flat, and until the Sauer kits came in, I'd never even bought a blank. Now I'll have the extra step of locating FCG holes via a jig. I'll let someone else handle any rewelding needs for me. I just don't trust myself enough on that part. Knowing the limits of comfort is part of the build process. It's fun to push the comfort zone a little to grow, but in general, choose your limits and build. If you want someone to populate the barrel for you, or have someone do the painting, go right ahead. If you just want to figure out how to attach the sling while someone else does the build, well that's you; do it; enjoy it. To each their own. I just really wanted to have a hand in the "journey" as they say. What I did here was more complicated than putting together an AR from parts, or even a FAL as long as it doesn't require any barrel-indexing trickery. But at the end of the day, it's just putting some pieces together little by little. It's not like I'm in the backyard trying to forge a barrel or anything like that.

Again, thanks for your kind words. If I can find the time, I'll get to work on the "AK-74N" being assembled from an R-Guns '88 kit. I might post that one in a more incremental fashion. I have everything in pieces and all the receiver holes drilled, but I'm not settled on how I'll pin the barrel components and am not 100% on the riveting process to get the optics rail rivets like I want them. I guess I'll bring you all along on the adventure, and I'll apologize in advance for the slow pace that will ensue.

pp