Step by Step Home-Building a HK-G 3battle rifle

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum 12/23/13, 7:18 PM User Name User Name

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

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06-01-2008, 07:13 PM

animator big bird

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Home-Building a CETME/HK-G3/PTR Rifle

So the latest rifle project I have officially kicked off is an HK/CETME/PTR rifle. My end goal for this build is to end up with an HK-G3 rifle, using a combination of CETME, PTR, and HK parts. I am also building off an Ohio Rapid Fire 80% flat. The first step was to acquire some flats. I will be building this with many of the same group of guys I built FALs and AKs with over the past few years, as well as a possible few newcomers. Either way, I'm definitely excited.

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

My list of compliance parts will be: US US US US US

Barrel Muzzle device Receiver Rear Stock Cocking Handle

I still need 2 US parts, and I hear rumors of triggers and hammers floating around. I will keep my eyes out for one.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 1 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

I will also be doing a clipped-and-pinned SEF lower. I intend to keep the SEF markings, however it will obviously be a Semi-only build. I'll post progress as it occurs, but it will not be a continuous thread. I'll post up my experiences during this build, so take them for what they are. Your mileage may vary. The first step (besides acquiring a CETME parts kit sans-barrel for all of 50 bucks from Centerfire way back when...) was to get an ORF flat. These were pressed off of original HK dies, so they should be identical to an HK receiver.

The next step is to press the receiver into shape. I have a bending thread posted that documents this, but I will post it here as well.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 2 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Complete with dummy bolt carrier

Start by placing your flat into the jig and centering it using the centering bolts.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 3 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Next, put the rod piece in. This is a round bar that basically forms the top radius of the bend. It is guided by slots on the front and rear of the jig. Begin to slowly apply pressure and watch as the flat begins to slowly form up.

Once pressure is applied, the ends begin to rise up (if you've done an AK, you are familiar with this) and keep applying slow gentle pressure on it, and keep both ends coming up at roughly the same pace. Every flat I bent tended to rise up on the left side a bit faster than the right, but they came out just

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

fine.

Keep pressing until the ends meet, and then do a little more. Remember that metal has memory, and will tend to bend back the way it was. So by going a little further, once it pops back out, the ends will be much closer than they would if you simply stop as soon as they contact. Be sure to check to make sure both ends are equal, or at least close. If they are not close, you *can* fix it, but it takes a LOT of effort (I know, because one guy bending with us had his get off-center, and we had to spend a lot of time getting them back right, but the good news is, it can be done.)

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 5 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Doesn't get much closer than that. And here's the final results:

__________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum:

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 6 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

http://www.pirate4x4.com/forum/outdo...-may-31-a.html Last edited by animator; 06-01-2008 at 07:57 PM.

06-01-2008, 07:14 PM

animator big bird

#2 (permalink)

So, the next step is to demil my CETME parts. Mainly, I'm interested in the cocking tube, trunion, and mag lock and release parts. I start by chocking up the cocking tube and trunion into a vice. Don't go too tight, otherwise you risk deforming your tube. Notice the plug welds, in addition to the weld where the tube meets the receiver.

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

Using a dremel with a cutoff wheel, I cut down the length of the receiver, as shown.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Flipped it over and did the same to the other side. You want to be careful and not cut too deep. There is a sleeve inside the receiver, and if you get too carried away, you will cut this sleeve.

With those two cuts, the trunion drops away, and can be set aside.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 8 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Next, I need to remove the excess scrap receiver still welded to the cocking tube. You want to be VERY careful while cutting this off. You can very easily cut into the cocking tube's sleeve, and ruin it. You also want to pay attention where you cut. If you cut your tube too short, you can potentially have issues with bolt-gap later on. I used tape to mark where I did NOT want to cut.

Now comes the hard part--the plug welds.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 9 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

I ground them down. You want to go slow here, and pay attention to the grinding tool. You can notice the metal seams as you break through the weld, so when you see the seams, stop, and begin to pry away the metal. On my kit, there were three plug welds on the side, and two on top.

Now the cocking tube is off and can be set aside.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 10 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

To get the trunion out, you will have to grind as many as 6 plug welds. There should be 2 on each side, and one on the bottom. Once these welds are ground out, peel away the scrap receiver, and set your trunion aside.

You can, if you choose, press in your barrel at this step. I would recommend it, as having the trunion

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

out of the receiver is the easiest way to do it. I will post more on the bolt gap and barrel pressing once that step is final. I mocked up the parts to see how it's all looking. I'm not happy with the 16" barrel, and instead will be getting an 18" barrel. 18's weren't available when I ordered the 16, but I've seen them back on the PTR website, so I will save the 16" barrel for a G3K clone for a future build.

More to come... next step will be to weld the receiver... I'll follow up with pics once that has happened... __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html Last edited by animator; 06-01-2008 at 07:16 PM.

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06-01-2008, 09:57 PM

Numidian

Zeus of the Sluice

#3 (permalink)

Looks like an oversized MP5 in that last pic LOL __________________ Brennan Nemo me impune lacessit

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 12 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Join Date: Oct 2004 Member # 36317 Location: Shrewsbury PA Posts: 4,499

06-02-2008, 07:34 AM

animator big bird

#4 (permalink)

Quote:

Originally Posted by Numidian Looks like an oversized MP5 in that last pic LOL

That's because a G3 IS an oversized MP5 Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

__________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

06-02-2008, 08:10 AM

Aces'n'8s

#5 (permalink)

Looks good. Do you plan to Tig or Mig the receiver?

Axes of E-ville

Join Date: May 2005 Member # 48097 Location: West TN Posts: 3,520

06-02-2008, 09:38 AM

animator big bird

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

#6 (permalink)

Quote:

Originally Posted by Aces'n'8s Looks good. Do you plan to Tig or Mig the receiver?

TIG __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

06-02-2008, 02:09 PM

aloharover I build stuff

#7 (permalink)

Quote:

Originally Posted by animator That's because a G3 IS an oversized MP5

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Uhmmm, nope. MP5 is a miniture G3 __________________ Want to know how I lost 35lbs? Try INSANITY®. www.beachbodycoach.com/petermhope

Join Date: Oct 2002 Member # 14561 Location: Just outside the evac zone Posts: 16,397

"Life is hard. It's harder when you're stupid" Colorado Springs, CO Based FFL-07/SOT

06-02-2008, 04:53 PM

Jason R

Registered User

#8 (permalink)

You should machine and weld a picatinny rail on the receiver...right in front of the drum site. Make it low profile and no need for the crappy HK clamp-on shit! __________________ This space for rent.

Join Date: May 2002 Member # 11598 Location: USA Posts: 6,062

06-02-2008, 05:59 PM

animator big bird

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

#9 (permalink)

Quote:

Originally Posted by Jason R You should machine and weld a picatinny rail on the receiver...right in front of the drum site. Make it low profile and no need for the crappy HK clamp-on shit!

I am way ahead of you on that... __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

06-03-2008, 09:14 AM

Grimjaw

Registered User Join Date: Jun 2004 Member # 32013 Location: Fort Mill, SC Posts: 433

#10 (permalink)

Quote:

Originally Posted by animator I am way ahead of you on that... Ok, that sounds interesting, very interesting..... What do you have up your sleeve? I may just steal the idea for my two. __________________ [QUOTE=My Wife] I was all geared up for sorched earth and by golly somebody's earth is getting scorched, darnit![/QUOTE]

06-03-2008, 09:18 AM

afroman006

#11 (permalink)

Me too, I have 1 1/2' of Scott's steel rail. Any chance I can send it up to you to get the radius cut on the

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 14 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum Registered User Join Date: May 2003 Member # 19615 Location: San Antonio, TX Posts: 1,582

bottom? __________________ Texas A&M Offroad 84 Chevy -Pigpen- Best trail truck there ever was...

06-03-2008, 09:47 AM

hoohaa

Registered User

12/23/13, 7:18 PM

#12 (permalink)

Wow, I will be watching this thread closely. I've got a CETME kit that needs to be built as well. Heck, I wish I had known you would have that flat bending jig, I would have bought a flat and begged to get invited to the "guys who build 68 rifles at a time club".

Join Date: Oct 2005 Member # 55546 Location: Dallas Posts: 932

06-03-2008, 10:38 AM

Gozuki

Pirate4x4 Addict!

#13 (permalink)

Quote:

Originally Posted by afroman006 Me too, I have 1 1/2' of Scott's steel rail. Any chance I can send it up to you to get the radius cut on the bottom? What is the radius? __________________ Quote:

Join Date: Jan 2001 Member # 3088 Location: West Coast, USA Posts: 11,786

Originally Posted by Crash440 I had a HARD ON for forgetting my meds.

06-03-2008, 10:53 AM

animator big bird

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

#14 (permalink)

Quote:

Originally Posted by hoohaa Wow, I will be watching this thread closely. I've got a CETME kit that needs to be built as well. Heck, I wish I had known you would have that flat bending jig, I would have bought a flat and begged to get invited to the "guys who build 68 rifles at a time club".

Buy some flats and I'm sure we can work something out. The guy whose jig I used is over in Ft. Worth. __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

06-03-2008, 12:19 PM

Grimjaw

Registered User Join Date: Jun 2004

#15 (permalink)

Quote:

Originally Posted by Gozuki What is the radius?

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum Member # 32013 Location: Fort Mill, SC Posts: 433

most likely it will be close to 7/8", but mine are not bent,yet. __________________ [QUOTE=My Wife] I was all geared up for sorched earth and by golly somebody's earth is getting scorched, darnit![/QUOTE]

06-03-2008, 02:08 PM

animator big bird

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

12/23/13, 7:18 PM

#16 (permalink)

Quote:

Originally Posted by Grimjaw most likely it will be close to 7/8", but mine are not bent,yet.

It's just slightly larger than 5/8". Some people use 5/8" rod clamped to a table to draw over their receivers. It's a crude method that produces only marginal results... __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

06-03-2008, 03:17 PM

afroman006 Registered User

Join Date: May 2003 Member # 19615 Location: San Antonio, TX Posts: 1,582

#17 (permalink)

So how're you doing the bottom of your rail? __________________ Texas A&M Offroad 84 Chevy -Pigpen- Best trail truck there ever was...

06-03-2008, 07:14 PM

animator big bird

#18 (permalink)

Quote:

Originally Posted by Grimjaw Ok, that sounds interesting, very interesting..... What do you have up your sleeve? I may just steal the idea for my two.

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

I've been talking to scott@rockstomper about getting a few lengths, and once I find out how much I will need, I'll be making an order. Once the rail is in, we'll figure out how best to weld it to the receiver. It will be similar to the welding required to mount the rear sight base, so I'm not too worried about it being too difficult or anything...

Quote:

Originally Posted by afroman006 Me too, I have 1 1/2' of Scott's steel rail. Any chance I can send it up to you to get the radius cut on the bottom?

You can send it if you want, or hold onto it for build day (which I still don't know when that will be). Either way, it will get welded on when the time comes. I'm in no rush for it, though...

Quote:

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Originally Posted by afroman006 So how're you doing the bottom of your rail?

Haven't figured it out yet. Once I see the rail, I'll come up with something... __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html Last edited by animator; 06-03-2008 at 07:15 PM.

06-03-2008, 07:59 PM

hoohaa

#19 (permalink)

I dont care what they say. CETMEs freakin rock!

Registered User

Join Date: Oct 2005 Member # 55546 Location: Dallas Posts: 932

09-13-2008, 05:54 PM

animator

#20 (permalink)

So getting this going again...

big bird

I had originally planned on doing this during a build party among some local friends, but I'm kinda tired of waiting on them... seems like everyone is caught up with other priorities, which is totally cool with me, but I'd like to get this gun built, and so I decided to just do it on my own.

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

Had originally planned to TIG it, but the TIG welding was going to be done by someone else. And since I'm doing it on my own now, I had to settle for MIG. MIG's fine for this, and many people have reported good results with MIG, so I'm using what I have. I started by clamping the magwell area closed. Almost all of this area gets cut out when doing an ATF-approved semibuild, so it's almost a waste to even weld it. I'm doing it to help hold the receiver together. I started by tacking everything together.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

With the magwell area tacked, I moved to the rear. You don't want to weld this together without the stock block in place. If you do, your receiver might be too narrow at the rear. I installed the stock block, and clamped everything in place, then tacked the two ends. With my heat settings set for sheet metal, I didn't worry about any burn-through getting on the stock block. It is such a thick piece of metal, you get absolutely no penetration when using sheet metal settings, so once the ends were tacked together, the stock block simply popped out with a hit from a hammer.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 18 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

The stock block needed a bit of sanding on the bottom. You can see how the holes don't perfectly line up. Personally, I'd rather have a block with no holes cut in it, but this works just as well. I sanded the bottom to try and get the holes a bit closer, but didn't make it perfect. That won't be a problem, because the holes for the stock pins need to be drilled out anyway, so I figured the amount it is off won't hurt it, since it will all be drilled out a bit larger anyway.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 19 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

tacked everything in place before doing final welding.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 20 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Receiver welded together. I blew through the end a bit, which I figured would happen.. lol. But I'm not worried about that. Once the trunion is installed, I will fill that area with weld. It kinda looks like the receiver was welded with a huge gap in the ends. This isn't the case, though. The ends were welded completely flush. I installed the front trunion before welding, to make sure everything fit. Then I removed the trunion before doing the final weld.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 21 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

The rear stock block was a bit tricky. To weld it in, I set the heat settings all the way up. I hit the block with the weld, let the puddle form, then walked it over to the edge of the receiver and let the puddles pool together. If you fuck up here, you will blow a huge hole right through your receiver. And those are never fun to fix.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

__________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

09-13-2008, 07:17 PM

animator

#21 (permalink)

Next up is the cocking tube

big bird

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 23 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

I drilled 3 holes on each side for the cocking tube sleeve. This is the same way it is done on the G3/CETME rifles from the factory, so I figured I'd do it this way too. Some people only weld the tube where it meets the receiver. I think the factory also puts two welds on top, but I didn't do those... mainly because I forgot to drill holes for them

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 24 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Then weld it on.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 25 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

__________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html Last edited by animator; 09-13-2008 at 08:13 PM.

09-13-2008, 08:10 PM

Grimjaw

Registered User Join Date: Jun 2004 Member # 32013 Location: Fort Mill, SC Posts: 433

#22 (permalink)

Very nice build so far. __________________ [QUOTE=My Wife] I was all geared up for sorched earth and by golly somebody's earth is getting scorched, darnit![/QUOTE]

09-14-2008, 12:03 PM

animator big bird

#23 (permalink)

So next up is the semi-auto shelf for the receiver. This piece is meant to block the installation of a full-auto lower receiver. It must be wide enough so that a full-auto lower receiver cannot be installed. It also blocks the pin hole for the full-auto lower receiver. I started by using a 3/8" piece of steel, cut to 20mm x 22mm (yeah I use both systems for measuring...

)

In hind-sight, I would rather use a 1/2" thick piece, but this will work just as well. I'm using my Century CETME as a goby for this, and the 3/8" is what they used. Join Date: Sep 2002

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Member # 13701 Location: Plano/Dallas Posts: 4,248

Then measure and mark for a chamfer.

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

I ended up going a bit deeper on the chamfer than originally marked. It didn't look deep enough compared to my CETME.

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Page 28 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Then measure and mark the receiver where it will be cut out.

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Page 29 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Then cut it out.

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Page 30 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Cut it just enough to allow the semi-auto shelf to slide in tightly.

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Page 31 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

And it is wide enough to clearly block an un-modified full-auto lower receiver.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 32 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

So next up is the paddle mag release switch. I can see why companies don't include the paddle mag release on their builds, as it is kinda a bitch to do. On my semi-auto shelf, I have measured and marked the area that needs to be removed to make clearance for the paddle.

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Page 33 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

And this is where you guys with your fancy milling equipment can go fawk yourselves with my dremel tool __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

09-14-2008, 12:04 PM

animator

#24 (permalink)

Rather than try to dremel out the whole opening, I drilled it out first.

big bird

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

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12/23/13, 7:18 PM

Then dremeled and hand-filed it to make it square.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 35 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

The ears of the lower receiver must be widened to fit on the semi-auto shelf. Some people simply cut these off, but I want a clipped-and-pinned style build, so I just sanded them down with a dremel until it fit.

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12/23/13, 7:18 PM

__________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html Last edited by animator; 09-14-2008 at 03:55 PM.

09-14-2008, 03:24 PM

animator

#25 (permalink)

And so, putting the receiver aside for now, I moved on to the barrel and trunion.

big bird

These are PTR 91 barrels that came from PTR inc. One is 16", the other 18". I am using the 18" for this build.

Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,248

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Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

Press the trunion onto the barrel. This was a fun experience. After pressing in the barrel, and checking my bolt gap, the barrel needed to press in further. So I pressed it in further. Then, after checking the gap again, I needed to press my barrel back out a bit. So I pressed it out a bit. Then, after checking the bolt gap again, I needed to press the barrel back IN again. This went on a few more times before I decided to throw a stack of pennies into the trunion. These stopped the barrel from jumping too far. Seemed to work pretty good...

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 38 of 41

Home-Building a CETME/HK-G3/PTR Rifle - Pirate4x4.Com : 4x4 and Off-Road Forum

12/23/13, 7:18 PM

I was happy with a .015 bolt gap. Spec is anywhere from .010 to .020 if I'm remembering correctly. I set the bolt gap before installing the trunion into the receiver. I've read alot of people doing it this way with no ill effects, but to be safe, I will check it again with it in the receiver before pinning the barrel and welding the trunion.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/688219-home-building-cetme-hk-g3-ptr-rifle.html

Page 39 of 41

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12/23/13, 7:18 PM

__________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

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