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7/15/2025 10:02:20 PM EDT
Soooo….ive finally got over the PTSD incurred from my HK-21 build (my first roller lock build) that I documented here:

ARF HK-21 Build Thread

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APEX had what looked like some clean FMP G3 kits in their email last week and I bit like a sucker. These are the “Select Matching” kits:

APEX Select Matching G3 Kit

I figured I would document this build too because it’s “nevah been dun befoah”. And because these threads are fun. To be honest…I think this build is going to be more difficult than the 21. Anyways…I ordered the APEX kit hoping the one I received was as nice as the one they had pictured. For $175 I was skeptical. The kit arrived today and I wasn’t disappointed. Stick around as I go through the demil process, figure out how the hell to populate the barrel in the trunnion properly, and pretend I know how to weld while glueing this thing back together.


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7/16/2025 5:08:58 AM EDT
[Last Edit: Colonel_Strelnikov][Edited] [#1]
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Can't wait to see the process unfold OP.

Thx 4 sharing.
7/16/2025 10:50:30 PM EDT
[#2]
Why didn't you grab one of the FMP barrels?
7/16/2025 11:07:30 PM EDT
[#3]
OST.
7/16/2025 11:41:33 PM EDT
[#4]
Darn it that is beautiful. Sucks I didn’t pick up a kit.
Elite Soviet Democrat
7/16/2025 11:51:03 PM EDT
[Last Edit: cms81586][Edited] [#5]
Quote History
Originally Posted By themao:
Darn it that is beautiful. Sucks I didn’t pick up a kit.
View Quote



They’re still in stock. Link is above. $174.99
7/16/2025 11:53:50 PM EDT
[Last Edit: cms81586][Edited] [#6]
Quote History
Originally Posted By RedFox1911:
Why didn't you grab one of the FMP barrels?
View Quote


Parabellum Customs did a review comparing a muzzle erosion on them. Gotta take it with a grain of salt because they definitely pump the RCM stuff, but the 3 FMP barrels they had all gaged worse than a HK21 barrel with 12-15k rnds through it. They’re near end of life. If some nicer barrels come in now that the barrel ban is all but defunct I’ll consider picking one up. That’s sort of why I’m in no big rush to buy one quite yet.


ETA: https://www.instagram.com/reel/DMF6HJxRiKz/?igsh=aTJqMmw0MnYzM29h
8/9/2025 10:37:24 PM EDT
[#7]
I got my kit today from apex. Mine came with black furniture. Now a need a barrel and recevier.
8/9/2025 10:46:49 PM EDT
[#8]
I have 2 kits with pulled barrels.  Both gaged little over 1 at the muzzle.  These are good to go.  

This specific HK smith build my MP5 clone about 10 years ago with the bolt gap less then .010. As I recall the gun want back to him twice.  At the end I end up using over size rollers to fix the gap.
8/10/2025 12:18:28 AM EDT
[#9]
Quote History
Originally Posted By Plumberguy:
I got my kit today from apex. Mine came with black furniture. Now a need a barrel and recevier.
View Quote



PTR receivers seem to have dried up right now…
8/10/2025 4:54:36 PM EDT
[Last Edit: bulletboy5150][Edited] [#10]
Quote History
Originally Posted By cms81586:



PTR receivers seem to have dried up right now…
View Quote View All Quotes
View All Quotes
Quote History
Originally Posted By cms81586:
Originally Posted By Plumberguy:
I got my kit today from apex. Mine came with black furniture. Now a need a barrel and recevier.



PTR receivers seem to have dried up right now…


Sarco just got some in https://www.sarcoinc.com/cetme-ptr91-g3-308-receiver/

I got a couple of kits myself and these will be my first builds so I will def be in this thread a lot. I'll be bending the flats using a 3D printed jig, I actually bent one so far which seemed to do fairly well, just need to get it welded up now. I may post some pics of the process soon.
8/10/2025 6:03:17 PM EDT
[#11]
Quote History
Originally Posted By cms81586:



PTR receivers seem to have dried up right now…
View Quote View All Quotes
View All Quotes
Quote History
Originally Posted By cms81586:
Originally Posted By Plumberguy:
I got my kit today from apex. Mine came with black furniture. Now a need a barrel and recevier.



PTR receivers seem to have dried up right now…


I got one of their receivers with a parts kit and whole box of mags at a gunshow, really only kept it for a reference when I bend my flats.
8/12/2025 9:10:08 AM EDT
[#12]
I’m in on this party, trading for one of these rifles later today
Game on!
10/29/2025 11:49:49 AM EDT
[#13]
Sorry I haven’t updated….Sarco went out of stock on PTR receivers and I forgot about this project a bit.
4/6/2026 5:51:30 PM EDT
[#14]
Started one of my builds with a surplus barrel I got from apex, not sure I can use this one even with my first build using the ugliest kit I got.
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4/6/2026 8:01:33 PM EDT
[Last Edit: cms81586][Edited] [#15]
Quote History
Originally Posted By XJ01-08:
Started one of my builds with a surplus barrel I got from apex, not sure I can use this one even with my first build using the ugliest kit I got.
https://www.ar15.com/media/mediaFiles/152238/3305_jpg-3742346.JPG
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I’d still use that…but that’s why I decided to just go with RCM. Less variables.
4/6/2026 8:46:08 PM EDT
[#16]
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Originally Posted By cms81586:



Is still use that…but that’s why I decided to just go with RCM. Less variables.
View Quote


I figured I give em a shot since they were $70 something, other one I got is in great shape. But yeah I have new barrels for the other kits I'm building. Also RTG flats really suck compared to PTR made flats, I found all the spots that are out of spec like the mag well has rounded corners in the front not squared like PTRs. What really sucks is finding that out after you bend it, would have been way easier to square up when it was still flat. I'm thinking I'll use one of them on my HK21 build since I have to cut that off anyway.
4/7/2026 6:05:28 PM EDT
[#17]
Relevant to my interests. Have a G3 kit sans barrel and am seriously considering building one. I’ve built AKs, Fal’s, Garands, Ar’s, but never an HK platform.

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