NY_crawlers build thread

[NY_crawler]

I want to get this thing rolling as it's been a few weeks since I got my receivers. I still need to figure out my compliance parts but was thinking of going the G3 trigger pack route with the parts from PTR. I also found this "muzzle brake" that looks like the original flash hider. Remember, I'm in NY with a mirror of the old AWB.
http://www.investmentgradefirearms.com/images/For%20Sale/hkbrakeside.jpg


My compliance parts would be as follows:
Reciever
Muzzle brake
Trigger
Sear
Hammer
Trigger
Trigger housing

What are all the little parts (springs, pins and such) that I need to order from RTG Gun Parts for the G3 trigger housing? I don't want to spend $85 for the G3 trigger pack just for all the little springs if I do buy the PTS trigger housing as it would be cheaper to get just the springs and such separately.

Also I was test fitting my cocking tube and trunnion together when I noticed that when I push the trunnion flush to the receiver rails that the hole in the receiver for the barrel does not line up (front to back). Any suggestions?

I'm sure I will have plenty of questions again as this is my first build and I don't want it to go boom in my face.

[Warwagon]

Whose receiver are you using? Although I don't have my receiver in front of me, that pin hole seems a little far forward as compared to the CIA cast stainless one I've got. If you've got a G3 receiver, the pin hole may be placed differently. I KNOW the G3 trunnions are different from those on a CETME, and the pin hole may be part of that difference. I really can't speak knowledgeably on this, as I have never had a G3 trunnion in my hands to compare them. Time to let those with more mental "bulk" on these matters weigh in ... :weight_lift:

[SSwee]

Maybe some pics will help. The FH looks US aftermarket. The ID is the same as I've seen on Tapco or IGF.
Pic of one of mine, Cetme original, HK original

Trunions are almost identical but not totally.
Pic of HK with barrel and Cetme without barrel.

SS

[texlurch]

AFAIK, all the receivers are made on the G3 stamping, so that explains the difference in the pin hole opening. Does yours also have the rear shelf for the G3 sight?

[NY_crawler]

It's a JDL reciever and I didn't know the recivers were diffrent. It does have the sight base already welded to it. Can I use the PTR us made tronion instead of the cetme tronion or would I have to get a HK barrel also? And it is a IGF brake. I just hope they have them in stock.

[weasel_master]

If you use an HK trunion you pretty much can't go CETME. The bolt is different as are the trunions. This won't allow proper lockup between bolts/trunion.

[NY_crawler]

So what have you all been doing for the diffrence in the hole locations between the receiver and the trunnion?

[texlurch]

Internals are different. To use the CETME rear sight, you'll need to remove the rear sight base also.

[texlurch]

So what have you all been doing for the diffrence in the hole locations between the receiver and the tronion?

Mine was pretty much perfect on my G3 build....


In your case, I would open it up to match the CETME trunnion, and then fill the edge when you weld the receiver up.

[okie shooter]

Crawler, I know you might not want to think about it, but since you are thinking aobut g-3 internals because you cannot swap those without the swap of the trigger pack, and you cannot use a g-3 trunnion with a cetme bolt and such, why not get a g-3 kit? I know that they are extra money but at this point if you are going to use compliance parts from a g-3, I think you might be money ahead to build a g-3 over a cetme for the future of parts and such too.(and since you have the g-3 receiver with rear sight mount too)

[NY_crawler]

Mine was pretty much perfect on my G3 build....


In your case, I would open it up to match the CETME trunnion, and then fill the edge when you weld the receiver up.

Ok will do. I take it I fill the egged out part of the hole in when I TIG the trunnion and cocking tube together?


Crawler, I know you might not want to think about it, but since you are thinking aobut g-3 internals because you cannot swap those without the swap of the trigger pack, and you cannot use a g-3 trunnion with a cetme bolt and such, why not get a g-3 kit? I know that they are extra money but at this point if you are going to use compliance parts from a g-3, I think you might be money ahead to build a g-3 over a cetme for the future of parts and such too.(and since you have the g-3 receiver with rear sight mount too)

I do plan on doing a G3 build also. I have 2 receivers and plan on doing one of each. I would like to keep the CETME as original as possible (looks wise).
Does anyone have an extra G3 kit laying around they want to sell or know of any that are in stock? The only ones I saw were the new ones from POF (http://www.pof-usa.com/mp5parts/G3partsset.htm) but their pic does not show that it comes with a lower. I might need to shoot them an e-mail and ask. If i can get the G3 kit in soon I will build that first and wait until I have all the parts I need for the CETME.

[texlurch]

Ok will do. I take it I fill the egged out part of the hole in when I TIG the trunnion and cocking tube together?


Exactly.

And as far as using the G3 trigger parts, you can still use the CETME grip frame so externally it looks like a CETME. The safety just works backwards.

[NY_crawler]

Thanks for that tip. Insstead of buying the US made PTR trigger housing I might just get the pistol grip instead. It looks the same as the CETME as far as I can tell.

[rustypirate]

First off, NY_crawler, you listed trigger twice on your parts list, so you are still 1 part shy for compliance. This can be made up for with a Pistol Grip or a Charging handle.

Next, you will need a G3 trigger frame and selector lever if you want to use G3 FCG parts as the pin holes are located differently for the CETME and G3.

The pin hole can be egged out to acomodate the CETME hole location as covered by the others here. If you want to remove the G3 trigger base and replace it with a CETME rear sight assembly, I have an extra set that I can be persuaded to part with, but it will have to be in a couple of months as I am in Europe on work until mid-July.

[kevin]

when did you get your flash hider from IGF? ive been waiting over a year for one from them!

[NY_crawler]

First off, NY_crawler, you listed trigger twice on your parts list, so you are still 1 part shy for compliance. This can be made up for with a Pistol Grip or a Charging handle.
.

I listed the trigger housing after the trigger. I think you miss read it. That would be counted as a compliant part but I think I will mod a G3 housing instead and get the pistol grip as you suggested as it would be cheaper.


when did you get your flash hider from IGF? ive been waiting over a year for one from them!

I just e-mailed them and they said they hope to have them in the next 4 weeks. I hope it's not the same answer he has been telling people for the last year or so.

[rustypirate]

I listed the trigger housing after the trigger. I think you miss read it. That would be counted as a compliant part but I think I will mod a G3 housing instead and get the pistol grip as you suggested as it would be cheaper.

From your post:


My compliance parts would be as follows:
Reciever
Muzzle brake
*Trigger
Sear
Hammer
*Trigger
Trigger housing

[NY_crawler]

Rustypirate, my apologies and thanks for the help in pointing that out! I have my moments when I can be a bit on the slow side. Did I mention I am sure I will need lots of help with this build?

So my new list would be:
Receiver
Muzzle brake
*Trigger
Sear
Hammer
Trigger housing
Pistol Grip.

[rustypirate]

You could also replace the trigger housing with a charging handle from black-market-parts.com

[NY_crawler]

Ok, I am going to try and get these guns built soon. I am still having a hard time getting compliance parts. I need a US made cocking handle as it looks like black-market-parts.com is out of stock. I think I will try and proceed for the moment and at least get the Gun welded together when I get rollers and some of the parts I ordered in.

I am going to build the G3 first before the CETME as I think it will be a bit easier.

So here are my questions:

1.Where else can I get a US made cocking handle besides black-market-parts.com?
2.What rollers should I buy and start with when setting bolt gap? Should it be a 0 size and then go to a +2 or so as it wears?
3.Also I know bolt gap will shrink so should I be aiming for a .020 to .017 inch gap for the build?
4.My last question is about sandblasting the receivers I have. I have had them for about 6 months and left them in my gun safe (with a dehumidifier) and the have a lot of surface rust on them. Is it ok to have them sandblasted inside and out to remove the rust or should it be some other type of medium?

Thanks for all the help so far.
Mark

Oh yeah. And my compliance parts so far are:
receiver
muzzle brake
hammer
sear
pistol grip
trigger housing

I am looking for a either a US made cocking handle or a trigger to have 7 parts

[rideronthestorm]

You could use a phosphoric acid based rust remover, like Naval Jelly. There is also a liquid spray/dip version which is my preference. Letting it sit for a bit causes a iron phosphate layer, similiar to parkerizing. I actually like it, so long as you clean and oil it. I use WD-40, then later a good oil after WD-40 evaporates. It is not as durable as parkerizing but keeps the rust away. Has anyone tried degreasing and doing a real parkerizing on top of the iron phosphate? Or will it need to be cleaned down to bare metal for real parkerizing?

[rideronthestorm]

There is a huge amount of CETME parts on Gun Broker right now. Most are original, which are great for spares or bolt gap repairs.

[NY_crawler]

There is a huge amount of CETME parts on Gun Broker right now. Most are original, which are great for spares or bolt gap repairs.

Unfortunately none of them are US made parts.

[Smokehouse69]

You could use a phosphoric acid based rust remover, like Naval Jelly. There is also a liquid spray/dip version which is my preference. Letting it sit for a bit causes a iron phosphate layer, similiar to parkerizing. I actually like it, so long as you clean and oil it. I use WD-40, then later a good oil after WD-40 evaporates. It is not as durable as parkerizing but keeps the rust away. Has anyone tried degreasing and doing a real parkerizing on top of the iron phosphate? Or will it need to be cleaned down to bare metal for real parkerizing?

To get the best results you need to really, really clean the metal before parkerizing and prepare the surface so that the zinc or magnesium oxide has something to bind to. The best way to do that is to media blast it, although sanding with 220 grit would probably work. Then degrease with brake cleaner and not touch it with anything but clean cotton cloths or paper towels, before dropping it into the parkerizing solution.

A good home-made parkerizing solution can be made by adding one ounce of phosphoric acid to a gallon of distilled water, along with about an 1/4 cup of magnesium oxide and a chunk of degreased steel wool.
Heat the water and acid to 180 degrees in a stainless steel or enamel pot big enough to hold the part you want to parkerize. Drop in the magnesium and steel wool, then support the parts with clean steel wire and submerge it in the heated solution.
It should fizz which will show you it is working, leave it in for 20 minutes, then take it out and rinse it off with distilled water. Take it out of the rinse and spray it down with WD-40 to displace the water. Then oil it with your favorite gun oil.
If you plan on painting with Guncoat on top of the parkerizing, then don't oil it or spray WD-40 on it. Wipe it down with Acetone or lacquer thinner to remove water. Then you can paint it and bake it in the oven to cure it.
Contrary to public opinion Parkerizing is really pretty easy and you can reuse the solution several times. Just add a little more phosphoric acid and other chemicals to the mix about every 3rd use.
I got this recipe off the internet and it works pretty good on small parts I did my gas cylinder on my M1-Garand and it turned out looking new, I will soon find out how it works on my Cetme stamped receiver. :thumbup:

[NY_crawler]

Well I finally am getting around to building this after about 2 years of having most of the parts sitting in a box. There has been a learning curve for me as I have never built something like this but with a lot of research, some cussing and plenty of time and patience, I finally have it finished. I did place a few pics in here that IU did not take as they were very useful.

This build will be from a G3 kit but a CETME is just about the same with a few differences. I will try and note them if I can remember. My CETME kit is halfway finished and will be finished here soon.

Here is my compliance parts for this build:
Hammer
Sear
Trigger
Fire control group (FCG) housing
Cocking handle
Muzzle brake
Barrel
Receiver

I know I have 8, but my kit came with a barrel so I thought I was good until I cleaned it up right before the build and noticed it was heavily pitted. So…..new barrel. Also I bought my JLD receiver before the flats were available so I will not cover that part.

Now I have no pics of the de-mil as I did this part when I first got the kit.

[NY_crawler]

First thing I did was to convert the FCG to semi-auto. I did not have to do really anything with the PTR-91 FGC housing already made for semi-auto, but here is the an old diagram.

I used this to convert the G3 FCG housing I am using for my CETME build and the only thing you need to worry about is cutting the front out then welding in the notch, and drilling one new hole for the semi-auto sear spring (You can buy a semi-auto sear spring or bend the old one. I choose to buy the new one for my CETME build).

[NY_crawler]

After I modded the FCG and housing, I installed the magazine release. At this time I have not installed a paddle release but might in the near future before I paint it.

It is time to test the magazine fitment. Install the trunnion pushing in until it butts up against the receiver rails. Insert the magazine. The magazine should have to be rocked in place slightly like an AK magazine. Push the magazine release button and try and pull the magazine straight down. If it pulls straight down, you need to file the end of the receiver rails so the trunnion slides in further until the magazine rocks into place. Take a little off at a time as you don’t want to over do it.

Some say you don’t need to do this, but I did as this was the way it was designed and I hoped it would eliminate any feeding issues.

[NY_crawler]

Next I focused on making the shelf that welds inside the lower receiver. The diagram shows the dimensions. I used some 1/8 inch angle iron (IIRC) to make mine as I don’t have a mill and just shaped it with a Dremmel. This shelf will be used to support the front of the lower receiver as you have to cut (or clip and pin) the front ears as part of the semi-auto mod.

This part is important and you might have to adjust it a bit. The alignment is critical because you want the ejector to rise almost all the way to the top of the slot in the bolt head to eject the spent casing when the carried moves to the rear. If the ejector is too low in the slot, it will not eject the spent casing.

Welding in the shelf can be a bit of a PITA. You can always drill two small holes on the outside of the lower receiver and plug weld it in.

While I was focusing on this part, I also cut the slot in the carrier where the auto sear would be tripped. This cut keeps the ATF happy.

[NY_crawler]

Next up is the barrel. If you need to press out the old barrel stub, The way I did it was to put the barrel in a barrel clamp, clap the barrel clamp to the arbor plates of the press, and then press out the old barrel pin. It was faster and easier then drilling out the old pin. Then I just pressed out the old barrel using a stack of pennies between the old barrel and an old socket I don’t use anymore.

[NY_crawler]

Now it’s time to press in the new barrel. You can press it in without the trunnion welded in place or you can weld it in first, and then press the barrel in. On this build (G3) I did it with the trunnion out and for the CETME I did it with the trunnion welded in place.

I tried it with just the trunnion but taking the bolt gap without the receiver was a bit hard, so I opted to weld in the trunnion then press the barrel in.

As I wanted to reuse the old front sight from the old G3 barrel for another project (new barrel came with a new front sight, I cut the old barrel right behind the front sight and used that to press in the new barred with a stack of pennies in-between.

Before you press in the barrel, take a half round file and file then sand the front and rear edges of the trunnion. Also get the edge where the slot was milled for the barrel pin. Then grease both the inside of the trunnion and the barrel with high pressure grease. This will prevent galling when you press in the barrel.

Bolt gap should be between .010 and .020. I aimed on the high side. Remember if you have to press the barrel out and start over, re-grease everything. When you are getting close, just press it in a little at a time and then check. Sometimes I would check 5 or 6 times when I was close but it paid off with a bolt gap of .020.

[NY_crawler]

At this point, I wanted to get the old front sight off what was left of the old barrel. I took a grinder bit on my dremmel and ground down there the sling pin was peened over then hammered it out. I knew they were soldered on, but the only thing I had was a propane torch so I thought I would give it a try. After a few minutes of heating up the sight, I could see the solder flowing out.

I found 1 inch square tubing I had laying around and it fit over the barrel perfectly and rested on the front sight. I used this to press off the front sight which came off very easily to my surprise.

[NY_crawler]

After setting the bolt gap, the barrel pin needs to be put in. If you have a mill, your in luck. I don’t have a mill so I took it to a machine shop. As the barrel is round, you need to mill a flat surface on the barrel. A 3/16th inch bit will work. After machining the flat surface, you can use a 3/16th inch drill bit to drill the hole. Next thing is to ream the barrel out. The barrel pin is 5mm or .1969 inches. You can ream it out to this or go a hair bigger. I got my reamer from here.

http://www.wttool.com/product-exec/product_id/35877/nm/M_2_High_Speed_Chucking_Reamer_USA

I also got a .1975 Z pin gauge from McMaster-Carr for my barrel pin. You can go slightly bigger if you want, as this is an interference fit, I wanted .0005 to .001 larger pin size then hole size.

[NY_crawler]

After pinning the barrel, the next thing is to weld in the trunnion. First thing is to drill the holes for plug welding the trunnion to the receiver. I used a ¼ inch bit.

When fitting the trunnion for welding, I looked through the receiver and made sure it was square and flush with the receiver rails. I even installed the cocking tube to check that that was ok.

When welding, I decided to tack the trunnion in place to check feeding and ejecting. I bought a few snap-caps and placed them into the magazine then hand cycled the bolt. Everything seemed to work just fine, but at this point if I did have a problem, it might be easier to fix it.

I finished welding up the trunnion (yes I am not the best welder in the world) and then moved on to the cocking tube.

[Buelligan]

Very nice pics.

[NY_crawler]

For the cocking tube, you want to have a small gap in-between the end of the bolt carrier and cocking sleeve. If this is not set correctly, you can have a very difficult time cocking the rifle or it might destroy the cocking tube by the carrier slamming down on the cocking sleeve.

Remember, as bolt gap diminishes over time, so will this gap. This is why it is important. As I had a .020 bolt gap, I cut out a .020 feeler gauge and double taped it to the end of the carrier. If yours is .015, use a .015 shim etc.

I put the carrier down the receiver locking it in place then pushed the cocking tube into the receiver aligning the charging handle to where I wanted it. Make sure you can get to the holes to push out the pin to replace the old charging handle with your new one.

Next I tack welded the cocking tube in place. I took the carrier out, took the taped feeler gauge off then re-inserted the carrier to make sure everything worked the way it should.

[NY_crawler]

When welding the cocking tube. It will want to pull to where you welded it. I decided this would be the best time to install the front sight.

I put some flux on the barrel and the inside of the sight. When I solder it on after test firing it, the flux will already be there and will make soldering it much easier. I took the tubing I used to press off the front sight before and used it for the new front sight.

After pressing on to the correct spot on the barrel (the cocking tube does not go all the way into the front sight, only part way) I installed the rear sights and inserted a laser bore sighter on the end of the barrel to get the front sight aligned left to right.

[NY_crawler]

After everything was set and aligned, I took a tool I made from ½ inch copper repair sleeve for a copper pipe (it goes over the ½ inch copper pipe and was about $3.50 from the local plumbing supply store), some all thread, nuts and washers and I inserted it into the cocking tube.

As this fit the CETME cocking tube perfectly and the G3 cocking tube is slightly bigger, I cut a small piece of aluminum from some scrap sheet metal to be used to wedge the bottom of the tool up against the cocking tube so when I weld, I will not get any burn through as it will act as a heat sink. I then finished welding the cocking tube.

[NY_crawler]

Again I checked everything for fitment and to make sure the snap-caps fed and ejected correctly.

Next was to grind down and sand out the welds to make the gun look good. As I live in NY, I have to permanently attach the muzzle brake. I pinned it into place which I don’t have any pictures of. Next thing will be to test fire the rifle, adjust the sight if needed, sand blast and paint.

[NY_crawler]

Very nice pics.

Thanks!:thumbup:

[Smokehouse69]

Very nice tutorial! :thumbup: