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gunplumber
June 13, 2017, 12:58
Heavily edited from WTB CETME Modelo A bipod.

Associate purchased a post-86 dealer sample CETME with a welded receiver. It is mix of A and B model parts, so I'm still not sure what it is. What I thought was a serial number prefix (B) may be the model, as my armorer manuals show two different C models (Navy and Army) with a C prefix. Yet the trigger group has a right side selector from a model A, but not the open-bolt function of an early A model. Got the carry handle too - Yipee!

Progress - gun is refinished, found the model A bipod and a model B (?) handguard, the original stock. Problem is the builder tried to convert it to take an HK wood shoulder stock and removed the sleeve from inside the bolt carrier. So the HK (larger diameter) captive return spring binds, and the A model non-captive spring has no shoulder to bear against inside the carrier.

I'll have him source another CETME carrier, which will probably be a model C, and hope it is interchangeable.

Barrel is an FMP and I swapped the HK triple frame for a CAI-neutered CETME, and then soldered the grenade ring from the HK onto the barrel. Missing the center ring, but it is important to keep this as inexpensive as possible.



http://www.thefirearmblog.com/blog/wp-content/uploads/2012/12/cetme5.jpg


Also - anyone know the consequences of firing 7.62 NATO in a 7.62 CETME? I imagine it is doable as on the FRs

bigstick61
June 13, 2017, 13:40
I'm not sure that I would fire 7.62 NATO in a self-loader calibrated for 7.62 CETME. On an FR-8, the action remains locked until it is manually opened, obviously, and all you have to worry about is if the barrel and action can deal with the pressures, which the FR-8 can, as they are about the same between the two cartridges. My understanding, though, is that there are real differences in a self-loader that can affect function.

tdb59
June 13, 2017, 15:15
....

Also - anyone know the consequences of firing 7.62 NATO in a 7.62 CETME? I imagine it is doable as on the FRs


Mark-

IIRC, the CETME load was (+/- ) 120 grain bullet at 2500 fps.

That would put pressures and bolt thrust quite a bit lower than 7.62 NATO.

...

ETA: Nosler data for .308 Win with 125 grain bullet shows a starting load of 41.5 grains of IMR 4895 @ 2670FPS in a 24" test barrel.

https://load-data.nosler.com/load-data/308-winchester/

........

seasmoke
June 13, 2017, 16:10
Not sure about the Model A carrier, but the B carrier has large lightening cuts along the sides where it rides the receiver rails. My CETME C came with a B carrier and would function using the old 124gr SB CETME 7.62 ammo. When I replaced the B with the proper C carrier it would not cycle, but worked fine with 7.62 NATO. Likely best to use the Santa Barbara 124 stuff or home-rolled in your CETME A build.

Just for random info, my CETME 7.62 SB ammo is head-stamped: T (Toledo) 2 digit date (62) and 7.62-C

bigstick61
June 13, 2017, 16:55
Mark-

IIRC, the CETME load was (+/- ) 120 grain bullet at 2500 fps.

That would put pressures and bolt thrust quite a bit lower than 7.62 NATO.

...

ETA: Nosler data for .308 Win with 125 grain bullet shows a starting load of 41.5 grains of IMR 4895 @ 2670FPS in a 24" test barrel.

https://load-data.nosler.com/load-data/308-winchester/

........

The CETME cartridge produces similar chamber pressures to the NATO cartridge. This is accomplished by using a different type of powder that burns at a different rate than that of the NATO cartridge.

From: Lanza Gutierrez, Col. Francisco. Tratado de Cartucheria. (Palencia: Empresa Nacional Santa Barbara, 1978), pp. VIII-307 and VIII-320. (Oriignal in Spanish: translation into English mine).

Cartridge: 7.62mm CETME, CSP-003

Number: 3001

New Designation: 7.62X51 CETME, mod. 57.

Bullet:...Weight: 7.85 + 0.15g

Powder: 25 gr. Degressive-burning, smokeless, single-base flake.

Ballistic Characteristics: Initial velocity 760 m/s. Muzzle Energy: 216 kpm. Chamber pressure >3,500 kg/cm2.



Cartridge: 7.62mm Spanish NATO, bimetallic bullet.

Number: 3026

New Designation: 7.62X51 Spanish NATO, Ordinary, mod. 63-1

Bullet:...Weight: 9.45 +/- 0.1g

Powder: 46 gr. Progressive-burning, smokeless, single base extruded.

Ballistic Characteristics: Initial velocity: 830 m/s. Muzzle Energy: 325 kpm. Chamber Pressure: >3,500 kg/cm2.



And from: Manual: Armas Individuales, M-0-8-2. (Madrid: Talleres del Servicio Geografico del Ejercito, 1986), p. 245. (Also in Spanish, translated into English by myself):

4.6. Ballistic and Numerical Data, and the Pieces Which Constitute the Carbine.

4.6.1. Ballistic Data

Calibre: 7.62mm

Initial velocity with CETME ball cartridge: 800 m/s

Initial velocity with NATO ball cartridge: 840 m/s

Maximum Pressure of the CETME cartridge: 3,300 kg/cm2

Maximum Pressure of the NATO cartridge: 3,500 kg/cm2

Effective Range: 1,100m

Most Frequently Employed Range: 300m

Trajectory Height at 500m, CETME: 0.75m

Given that the data from the first source comes directly from the ammo manufacturer, Santa Barbara, and is a more technical treatise specializing in ammo, I would say where there is conflict that the first source is more authoritative, but even the second source shows that the difference isn't exactly large. The CETME cartridge does produce less recoil energy, however, which would explain the need for lightening cuts on the bolt carriers intended for that cartridge.

21HK
June 13, 2017, 17:39
WTB CETME Modelo A bipod. Not Modelo B/C

http://www.thefirearmblog.com/blog/wp-content/uploads/2012/12/cetme5.jpg

Also have a wood HK stock set on this model A which does not work. Trade for Cetme?

Also may need a carry handle.

Also - anyone know the consequences of firing 7.62 NATO in a 7.62 CETME? I imagine it is doable as on the FRs

Is this an original model A?
Good luck with the carry handle, took me years to find one for a model B clone build. I have never seen a model A bipod for sale, here or abroad.

If you have the original back plate/recoil rod assembly, the back plate is different on the model A and B....the CETME C wood stock is cut the same as the G3 stock and is for the tapered back plate and will not fit properly.

http://i677.photobucket.com/albums/vv139/OURVISIONS/Misc/B%20amp%20C%20stock%20difference_edited-1%20Custom_zpsmju6eoeo.jpg (http://s677.photobucket.com/user/OURVISIONS/media/Misc/B%20amp%20C%20stock%20difference_edited-1%20Custom_zpsmju6eoeo.jpg.html)

gunplumber
June 14, 2017, 08:36
It's a Model A post-sample machinegun. Selector on right side, which is weird. Reweld from way back but looks sound - very nice tig work.

Just in for cleanup, refinish and replace a few parts. Like I said, my associate bought it with the HK stock & return spring assy, and forearm. I need a CETME stock & ferrule &forearm, or bipod instead of forearm.

Data says it is supposed to be semiauto closed bolt and full auto open bolt but I haven't gotten it stripped yet - got a bout 30 FALs in front if it in line, although I don't think I'll be able to contain my curiosity that long.

What it should look like:

https://upload.wikimedia.org/wikipedia/commons/f/fd/StG_CETME_A2b_%281%29.jpg

Apex has the B/C/L bipod which is QD and attaches to grenade ring.

https://www.apexgunparts.com/media/catalog/product/cache/1/image/800x800/9df78eab33525d08d6e5fb8d27136e95/1/9/19jul16_cet-bpd_mid02.jpg

21HK
June 14, 2017, 10:18
The link for the bipod is for the model C and L, the model B is not a QD and attaches to the collar behind the front sight...for use with the metal hand guard only.

If there's a chance of the owner allowing pics of the FCG on that model A, I'd be interested in seeing what it looks like....for that matter, I wouldn't mind seeing the whole rifle.


Found some different pics in my files of the model A bipod...looks as though the clip that secures it to the barrel is prone to breaking.

http://i677.photobucket.com/albums/vv139/OURVISIONS/Misc/24738456_6521906%20Custom_zps5mlwhizc.jpg (http://s677.photobucket.com/user/OURVISIONS/media/Misc/24738456_6521906%20Custom_zps5mlwhizc.jpg.html)

http://i677.photobucket.com/albums/vv139/OURVISIONS/Misc/24738456%20Custom_zpsrbjk3pd7.jpg (http://s677.photobucket.com/user/OURVISIONS/media/Misc/24738456%20Custom_zpsrbjk3pd7.jpg.html)

http://i677.photobucket.com/albums/vv139/OURVISIONS/Misc/24738456_6521894%20Custom_zpssd4nn5zx.jpg (http://s677.photobucket.com/user/OURVISIONS/media/Misc/24738456_6521894%20Custom_zpssd4nn5zx.jpg.html)

gunplumber
June 14, 2017, 12:07
The link for the bipod is for the model C and L, the model B is not a QD and attaches to the collar behind the front sight...for use with the metal hand guard only.

Yes, that is the one I'm looking for. This has no ring in front of the triple frame. I posted the pic of what it IS NOT.

If there's a chance of the owner allowing pics of the FCG on that model A, I'd be interested in seeing what it looks like....for that matter, I wouldn't mind seeing the whole rifle.

It's a ugly but functionally welded post-sample - just going to repark it and replace the nylon spring guide washer with a steel CETME one, if I can't replace the whole HK wood stock/return spring assembly with a CETME. Model C is better than nothing, but I'd prefer the earlier B or A.

I am going to document it thoroughly, just 'cause it's interesting.

He also picked up a posty Izzy LB(ish) built on a rewelded G1 receiver. I'm going to photograph all the markings on that receiver, but it is otherwise uninteresting. I'd never seen a Modelo A before, I note from images there are two types - one has the selector on the left and the other (this one) has it on the right.

gunplumber
June 14, 2017, 15:02
Turns out, it's a Portuguese FMP barrel and triple frame on it. While I have a CETME triple frame, it's not worth the cost to the customer to change it. I'm not seeing any major difference on the carrier. If I can't come up with a CETME stock, and return spring, I'll just fabricate a spring capture sleeve for the HK guide.

Blackwing
June 14, 2017, 16:45
On the "B" that I have and the "A" that I've seen, there is no spring capture on the return spring. It just pressures up against the sleeve internal to the carrier.

21HK
June 14, 2017, 17:09
FMP front end, HK back end....doesn't seem like there's much CETME A left except for the receiver and lower?

I guess if there's a CETME trunnion and bolt group or FMP/HK trunnion and bolt group there shouldn't be an issue with 7.62 NATO.

Albatross52
June 14, 2017, 21:51
I have one of those CETME 30 rnd mags if you are interested. It locks up tight in my HK's, not so much in the PTR, I have had feed issues with it in my HK's. Runs fine in my buddy's CETME though.
Travis

gunplumber
June 27, 2017, 08:10
Woopie. Got the parts. Swapped out the HK triple frame for a model C triple frame - wrong ring for grenade launcher, but there's only so much I can do on a $200 post sample.

Got bipod and handguards not shown in image, carry handle and A model stock. Now I need a buttplate and one nut for one bipod leg. It's finer than a M5x0.5 and I can't tell what it is. about a 40 tpi equivalent. Slit like an early 2 slot StG 58 bipod nut.

Return spring is now correct non-captured version, and I found my old spanish armorer manuals, while mostly Modelo C, still have a few of the Model A comparisons.

gunplumber
June 27, 2017, 17:21
Found some different pics in my files of the model A bipod...looks as though the clip that secures it to the barrel is prone to breaking.

Well, it must be a model B then. Maybe with a model A grip frame?

Still need a buttplate, and I just have an HK cocking tube cap on it now instead of the on-board cleaning kit.

This is "before"

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-01.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-02.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-03.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-04.jpg

gunplumber
June 27, 2017, 18:02
After

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-01.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-02.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-03.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-04.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-05.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-06.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-07.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-b-08.jpg

yellowhand
June 27, 2017, 19:10
wow!

hkshooter
June 27, 2017, 19:30
Never seen a rewelded sheet metal receiver before.
Thing looks crude. But also looks much better after some GP magic.
Does this mean you are taking HK work, Mark? I have a project. :whistling:

gunplumber
June 28, 2017, 08:13
Never seen a rewelded sheet metal receiver before.
Thing looks crude. But also looks much better after some GP magic.
Does this mean you are taking HK work, Mark? I have a project. :whistling:

No - just FAL and refinishing. This was supposed to just be blast and park.

I still have enough FALs in and coming in that I can't take on any new AK or HK work at this time.

I really did not want to swap triple frames on this (or do anything other than refinish), but I had one in my bin, and the gun was so close to being correct, that I did it for him anyway.

hansellhd
June 28, 2017, 10:25
That's a beautiful hard to find collectors Gun, Nice job on the restoration.

21HK
June 28, 2017, 23:50
Well, it must be a model B then. Maybe with a model A grip frame?

Still need a buttplate, and I just have an HK cocking tube cap on it now instead of the on-board cleaning kit.


Grip frame on that gun is correct for the model B, the selector is on the right for both the A & B. ...how the heck did you come up with the correct back plate/recoil assembly and model B butt stock so fast? I've been looking for a B stock for a while now.

That is correct front tube cap for the B, smooth, made of aluminum.
http://i677.photobucket.com/albums/vv139/OURVISIONS/CETME%20kit%20build/CETME%20B87113%2014-001_zps1yxqx6ks.jpg (http://s677.photobucket.com/user/OURVISIONS/media/CETME%20kit%20build/CETME%20B87113%2014-001_zps1yxqx6ks.jpg.html)


Your probably going to have to make the bipod nut, I had two made for mine.
The tap I used was 5mm x .5. It was close but still not exact. With fingers crossed I started the machine screw into the nut and gently screwed it in a little at a time backing off each time I felt resistance...I didn't want to bugger the threads on the screw. I think that the .5mm thread pitch is correct but it's probable that the mating new sharp ID threads to used OD threads on the screw is what made for the tight fit.

http://i677.photobucket.com/albums/vv139/OURVISIONS/CETME%20modelo%20B%20build%20CETME%20modelo%2058/36._zps5ajkwqzk.jpg (http://s677.photobucket.com/user/OURVISIONS/media/CETME%20modelo%20B%20build%20CETME%20modelo%2058/36._zps5ajkwqzk.jpg.html)

http://i677.photobucket.com/albums/vv139/OURVISIONS/CETME%20kit%20build/M5%20x%20.5_zpsk7obwztg.jpg (http://s677.photobucket.com/user/OURVISIONS/media/CETME%20kit%20build/M5%20x%20.5_zpsk7obwztg.jpg.html)


Let them know if they want to cut the reciever in half where it was cut before, right above the selector...I'll buy the parts kit.:]


.

21HK
June 29, 2017, 00:03
Any way to get a couple of pics of the FCG out of the housing?...thanks!

gunplumber
June 29, 2017, 08:48
As I mentioned before, I got around 4 turns on the nut before it bound up. So whatever it is, is close to M5x0.5, but I don't believe it is the same. I don't think my customer cares enough to have me make a nut. It might be half what he has in this whole thing.

I also note that my model C triple frame lacks the contour of the one in your image.

Guy who had the parts kit found the stock which would have been included in the original deal if he had it available.

Still need a buttplate.

I'm going to try a different bolt carrier, model C - I've never seen the internal carrier spring sleeve as a separate item.

Oh, and your pic shows the difference between the CETME grenade ring and the HK one I stuck on this gun. - it was all I had available.


Here are some pics I took of the trigger assembly during disassembly. Looks pretty standard. Don't work on them often and don't have one to compare.


http://www.arizonaresponsesystems.com/wp/hk/cetme-a-10.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-09.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-13.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-15.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-17.jpg

http://www.arizonaresponsesystems.com/wp/hk/cetme-a-19.jpg

21HK
June 29, 2017, 10:36
... I don't think my customer cares enough to have me make a nut. It might be half what he has in this whole thing.
Sorry that he feels this way:facepalm:... if he's interested in making a parts kit back out of it, I'd like to hear from them.



Here are some pics I took of the trigger assembly during disassembly. Looks pretty standard. Don't work on them often and don't have one to compare.


Mark, thanks for sharing these. It is definitely the early trigger group, I've never seen anything more than an illustrated drawing of one of these.

gunplumber
June 29, 2017, 17:40
Mark, thanks for sharing these. It is definitely the early trigger group, I've never seen anything more than an illustrated drawing of one of these.

The trigger mechanism housing has a keyway for selector on both sides, suggesting the selector and grip frame fould be changed to move selector from the right side to the left.

I thought it was interesting that the auto sear and the trip were all one piece. I've only seen that on an early (Hard Times Armory?) Full auto conversion done on a semi only trigger housing - HK parts didn't used to be so plentiful, so people had to make their own for conversions.

APEXgunparts
June 29, 2017, 19:25
I believe this is the part you need to replace what was removed from that CETME bolt carrier:

https://www.apexgunparts.com/rifles/cetme/cetme-c/cetme-c-bolt-carrier-guide-rod-spring-stop-sleeve.html

https://www.apexgunparts.com/media/catalog/product/cache/1/image/800x800/9df78eab33525d08d6e5fb8d27136e95/c/e/cetme_20recoil_20rod_20stop.jpg

You may want to contact Customer Service about the butt plate.
APEX has ALL the remaining spare parts that came from the factory at Santa Barbara after GD took it over.

Richard

gunplumber
July 05, 2017, 07:58
So I was pulling some pics of a Golden State /Santa Fe G3 I had refinished some 25 years ago, and noticed the bipod and handguard were the same. Interesting.