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· Registered
2,851 Posts
Discussion Starter · #1 ·
There is a lot if information out there for both types of builds but what are the advandtages of both vs. the down side. I think this would be helpful to a new builder or someone thinking about getting into it.

· Registered
12,811 Posts
I've been mauling this over in my mind too since I decided to make the jump into building.

I decided my first would be screwed together.

Here are my reasons and I'm not telling anyone they should do it one way or the other.

1 Cost, it's easier fo me to jump in now not buying a press to take the barrel out or for riveting.

2 Tapping I know how to do it and have the taps.

3 Taking it apart again. I thought that was a really cool idea! If you want to change something you can take it all apart for re-finishing or even setup 2 different receivers matched to the same front assembly. Maybe you could have one with an underfolder and one setup like a Norinco Hunter.

4 Slightly easier to do screw together and even the rails can be bolted in as Max showed us.

Eventually I am going to get a press and spot welder. At that point I'll do a rivet build.

Just my thoughts. What I really should be doing is building my AMD instead of hanging here as it is pretty warm, but I don't feel good.

· Registered
4,013 Posts
I have done mostly rivet jobs however I chose to screw my AMD63. the reason I used screws on the AMD63 is because the trunion was allready installed onto the barrel. when a kit comes with the barrel and trunion togeather I have no real desire to take them appart then press back on. It just seems unnesesary and would "for me" require makeing or buying another tool to seperate them. As for downfalls I realy did not see any downfall to the screw togeather meathod. I liked it so much that I did not fill the allen heads in and I feel it looks good.
If the trunion is allready off the barrel then I like to rivet the trunion to the reciever then press the barrel into it :) no downfalls this way either. now that I have done both methods I feel they are equal only differant but neither one is better when done. the kit I buy desides and how it was taken appart decides if I am going to rivet or screw.
ps you may not need a press at all for for a screw meathod if the barrel is allready in the trunion, I guess that could be thought of a real advantage to a first time builder!!!! #21 drill 10-32 taps is a lot cheaper than a press :)

· Registered
727 Posts
I have done both. I waited until I could duplicate the look of rivets with the screw that I was using. I just don't like the look of standard button head screws. They do work though, wity a minimum amount of effort.

· Happy Camper
7,801 Posts
Here's what it came down to for me:

Screw Build Pros:
- Easier Process:
1. Drill out old rivets
2. Tap screw holes in trunions
3. Align holes in receiver & enlarge receiver holes if needed (like on a Hesse/Vulcan receiver)
4. Screw & loctite together

- Fewer tools needed (besides normal shop tools):
1. Tap(s)
2. Tapping fluid (aka cutting oil)
3. Drill/Drill Press
4. Vise (or some other way to clamp everything down... C-Clamps could work).

- Easy for disassembly/reassembly of new parts for model changes (barrel swapping, etc).

- Headspace is already set... using the parts kits as a foundation, the rifle should already be headspaced. If so, this saves the cost of headspace gauges & headspace process. If you need to headspace, you have to do most of what you would need if you riveted the rifle.

- Sturdy design. Many screw builds are out there & I have yet to hear of long-term problems. Even if there are problems, one can always go buy more screws & replace the old ones! ;)

- There is ample room for screw-ups. If/when you screw up a hole, you can enlarge it to a bigger screw size.

Screw Build Cons:
- Not as "true" to the original design.
- Visually, some people don't like screw heads.
- Assumes parts kit & pre-set headspace... definitely more work if headspace is needed.
- One-way decision... tapping the trunions alter them beyond usage for anything other than a screw build.
- Availability of parts kits on the market is hit-or-miss.

Screw Build *Potential* problems:
- Tap alignment, making crooked holes.
- Broken taps >> this is the most common problem.
- Mis-matched holes bet. trunion & receiver, causing the need to enlarge/egg-shape/redrill the existing holes.
- Long-term usage *may* cause the need to replace the screws over time.

I hope this info helps, like I said it was how I convinced myself that it was worth at least trying out. Now that I did, I have zero problems recommending the screw build method to a novice, and probably would recommend it for most of those people that want to build but don't want to jump in to the deep end of the pool from the start.

- Jerry

· Premium Member
7,158 Posts
The screw method works good and everything seems to go together fine, but someday I would like to be able to have everything necessary for doing a build with rivets. Also it is nice to be able to remove things if a mistake was to happen (it is easier to work on things outside of the receiver).

Even though having the trunion with the barrel already installed makes it easier, i would still recommend buying a set of headspace gauges to just be sure. Even though I don't have the handsomest face, I value it along with the rest of my body and would hate to have a gun come apart when shooting it due to headspace issues.

I have two front ends that I made the same mistake on (the lower screws on the front trunion weren't done correctly) so I have 1/4-28 screws in that area instead of 10-32. But it was a good lesson learned and taught me to be more careful in how I drill and tap, etc.

One other pro to the screw build method is that it saves me from buying to much equipment and helps to keep my wife happy (she doesn't want me to spend to much on my hobby, lol). I agree hcpookie you have pretty much covered the pros and cons.

· Gunco Irregular
4,303 Posts
hcpookie said:
- One-way decision... tapping the trunions alter them beyond usage for anything other than a screw build.
- Jerry
That's the 1st time I've heard that you can't rivet after tapping your trunnion. I was wondering why you can't just go ahead and use slightly bigger diameter rivets after tapping? BTW, I'm not argueing, just asking, as I've come to hold your opinions in high regard !

· Registered
1,546 Posts
I haven't started my AMD-63 build yet. But it will be a screw job. The reason is ......I'm learning. Yes I am slowly getting the tools (7.62x39's trigger guard riveter and plinker762's riveter, Xebec's barrel tool), but I would like to understand just what I'm doing first. I also got the spot welder from HF and I'm still learning/making stuff on/for that.

I just think that the screw job is the first build (for me) way to go....besides it would be just one more variant.

As far as 'Once screwed always screwed', I don't believe that. The aircraft industry replaces worn/mis-shapen rivets all the time, even on major structural components which means increasing the rivet size. So, I wouldn't think twice about removing the threads and installing rivets if there's enough metal to do so. Although it might look strange as to the size you would have to use to properly fit the re-sized holes.

I'm not in any race to get a build finished, and I'm not a machinist. I just would like to finish the first build with the least amount of screw-ups (lol) as possible. Like they say, 'Measure 10 times, cut/drill once, maybe

· Registered
48 Posts
My take on screws versus rivets

I built my last Bulgie '74 with buttonhead screws and it came out FANTASTIC! Here's a reprint of my ARFCOM post on it. I'll try to elaborate more if anyone has any questions. The only thing that I am going to change for my next build is to use 1/4x28's instead of #10's . . . they get a much better grip on the trunnion.

BTW, I took it tho the range and it was DEAD ON without any sight adjustments at 100M. Bulgarian craftsmanship at it's best.

[font=verdana, arial, helvetica]I finished mounting the trunnions on my KVar Bulgy AK-74 kit last weekend. It'd been sitting for 6 months waiting for "the right tools" - which I can't afford (just started a business AND bought a house), so I finally just decided to make do with the tools I have. I figured that I would list some of the the steps that I use in case someone else out there doesn't have a press and I DYING to get their AK done.

Plus, I'm not saying that this is the correct way (or the safe way) it's just the way that worked for me.

* First, I got the old sheetmetal receiver stub off of the front trunnion. I tried my Dremel tool with a but after an hour of sweat I borrowed my neighbors grinder . . . five minutes later the receiver stub was gone and I realized I had one more tool that I HAD to buy

* I then tried to get the rivet remains out of the holes in the trunnion. For the life of me, I couldn't get even one all of the way out. I realized that I was going to need to press out the barrel somehow. Considering my distinct lack of a press, I was left with a hammer and a variety of beating implements. First off was the barrel pin . . . after breaking a punch and nearly fracturing my wrist with a 16 oz framing hammer, I broke down and made a quick trip to Home Depot and grabbed a new punch and a 4 lb mini sledge. That bastard was coming out one way or another. It's AMAZING how hard I had to hit it to move it. Once it started and broke the shear plane, it came out with only a minimum of swearing. Which left me with the barrel in the trunnion . . .
. . . I just dropped 3 pennies against the chamber face, hooked the back of the trunnion over a secure flat metal surface, placed a 7/16 deep well socket against the pennies, and proceeded to lovingly and carefully beat the living shit out of the thing. Some advice if you do this - have plenty of pennies, they don't last long AND wear thick leather gloves (don't ask me how I know this) AND use a Craftsman socket so that you can exchange it once you mash it into scrap. I was careful to watch the barrel face and trunnion for damage and eventually the barrel popped free. I then proceeded to dance around the shop waving both parts above my head, shouting a victory chant much to the concern of my poor long suffering wife (I have WAY too many hobbies). I then drilled the rivets and punched them out.

* I was using a hardened OOW receiver, so I needed to lay out the drilling pattern for the screws. This part really made me sweat because I knew that once I drilled a hole it would be permanant - I don't have access to a welder AND it would screw up my heat treating. So, I measured 453,276,920,768 times and drilled once. I popped everything into my el-cheapo press, clamped the receiver down and drilled with the trunnions visegripped into place in the receiver. After using a small bit to check alignment I ran the bit all the way through the trunnions to get both sides in one shot. It worked perfectly.

BTW, Chris at AK-USA heat-treated my receiver. It really didn't make any differance in the build. I used cheap HSS bits and it cut the steel like butter as long as I used cutting fluid.

* After drilling it was time to tap. Let me say ahead of time that I have never tapped a hole in my life. I'm a network engineer by day which means that I'm pretty good at designing a 2 million dollar EMC SAN Fibrechannel storage solution, but pretty worthless in the shop with hand tools. So this part scared the bejeezus out of me. I kept hearing stories about folks breaking taps in the freakin' trunnion holes even when they used really nice quality taps. I looked on my shop table at the $3.88 10-32 HSS tap that I got at Home Depot and decided that I was not going to be outwitted by an inanimate object. If you've never tapped before, the following ideas may be helpful.
- Get and use a good quality tapping/cutting oil. Use LOTS of it. In my (albeit limited)experience, there is no such thing as TOO much
oil. Oil has the added benefit of removing heat.
- Go slow. If you're in a hurry it will not turn out well. I made myself take a five minute break between holes.
- Heat is your enemy. Tapping creates an immense amount of friction, which creates heat. Lots of it. Enough that you may need gloves to hold your work. As your work heats, the tap expands. This will make your holes oversize and increase your risk of tap breakage. Go slow, reverse often and give the tap time to cool and break chips.
- IMNSHO, don't use a press mounted tapping rig. I rigged one up and it seemed to be much more difficult to align because there was no "give" in the system. I just held the parts in my hands and used gloves.

I'm proud to report that I was able to complete both trunnions with one tap.

* Then, after checking the trunnion fit in the receiver(pretty much perfect) I decided to remount the barrel. Once again, I had no press AND brute force would not work this time. Beating a barrel OUT is much simpler than beating one IN. So, following the advice of those before me (you guys) I tossed my barrel out into the snow (it was 15 F) and grabbed my propane torch and carefully heating the trunnion up. I ran outside, got the barrel and tried to insert it into the trunnion. It went in 1/4in and stopped cold. Out came the pennies and the much-abused 7/16 socket and I removed it again. I then proceeded to spend an hour beating my head against the wall trying to rig up a car jack as a barrel press (admit it . . . you've tried or though of this at least once). I finally really looked at the barrel journal and noticed that the thick black paint on the chamber end was what was blocking the barrel from being inserted. Out came the 220 grit and away the paint went. I threw (well, placed gently) the barrel back out into cold and heated the trunnion. I grabbed my gloves, got the barrel and tried to slide the barrel into the trunnion . . . WOOHOO! Perfect fit, right on the barrel pin line with NO EFFORT AT ALL. You could have knocked me over with a feather. Maniacal chanting ensued . . .

* Finally, i had to replace the [email protected]$%#[email protected] barrel pin. After my experience with heat/cold though I was much better prepared to do this. Cold pin + hot trunnion + 4 lb sledge + two smashed fingers = inserted pin.

* Create plate for trigger guard, contersink receiver into trunnion, cut bolts, toctite, blah, blah, blah. Everything else was easy.

Well that's my adventure SANS press. My advice - get a press and avoid the headache. I'm building a GT PMKMS kit next and I'm waiting for proper funds for the right tools. But, if you're as impatient as I am, good results can be achieved.

· Registered
42 Posts
Screw vs. rivets

My first five builds were rivet builds. I just completed my first screw build last night, an AMD-63. I got to tell ya , I enjoyed it a lot better than riveting and I have all the riveting tools etc. No aligning the rivet jig just so so , and changing over to the next hole location or coming at it from another angle , changing tool heads etc. etc. Just tap and go for it. I really enjoyed the screw method more. Weird huh ? I pressed out the barrel which made it a real snap to thread the holes in the trunion , then pressed it all back on. Then put it all together. I also used 10/32 screws , turned them down by chucking them up in the $99.00 Sears drill press and applied a new file to remove the material. After I srewed the whole thing together ( after test and fitting everything) I filled in the screw head with "Duramix" glue , let it dry and sanded down to look like rivets and Whalla ! It headspaced perfect and looks great. :woot:

· Happy Camper
7,801 Posts
Grendeljaeger said:
That's the 1st time I've heard that you can't rivet after tapping your trunnion. I was wondering why you can't just go ahead and use slightly bigger diameter rivets after tapping? BTW, I'm not argueing, just asking, as I've come to hold your opinions in high regard !
Yeah no problem - that's what we're here for! I should have been more clear...

The reason I mention this, is that the trunion holes will be larger and therefore the original sized rivets won't work, they are now too small. Going to a larger rivet would mean custom fabrication of some rivets from 3/16" shank rivets. Lots of extra work on the drill press with a file and a box of 3/16" rivets from McMaster-Carr. File them down to about 11/64". Not a large amount of material, but does require a bit of effort. I did this for my Chinese pre-ban addtion of an AK-100 style folding stock. Pics here, about half-way down I start talking about the 3/16 rivet filing:

Then there's the problem of making larger holes in the receiver, arguably a much easier exercise.

You would probably want to drill out the threaded holes in the trunion, just to be sure the rivets have enough material on the trunion to grab on to... proper rivet setting requires the rivet shank to contact as much of the material to be riveted as possible... therefore a threaded hole would be subject to loose rivet fit and premature failure - thus the need to ream out these holes. Therefore IMO this step should not be skipped.

THEN you have to press these larger rivets - shouldn't be a big problem with the right jigs, right? :)

Therefore, YES you CAN resort to rivet use if you don't mind the extra work it creates. There is one caveat that I haven't considered, and that is the trunion cavity where the rivet shank swells - these spaces are designed for those smaller rivets, and I do not know what would happen if the rivet shank doesn't have enough room to swell - may not set properly, don't know for sure.

- Jerry
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