So... whats it take to build a Cetme?

[Gunaria]

Here's something that you can use as a reference;

http://www.smcomp.com/~smurph/G3-build.html

[FEDUPWBS]

AJAX, I have a welding fixture for the cocking tube and MIG and TIG welder at your disposal anytime as usual. Oh yea and a lathe to for separating the tube from the stub. LMK.

[AJAX22]

Thanks Fedup, Yet another reason to head up your way..... I better be carefull or I'll wind up with too many projects earmarked as "hold for fedup build session"

I didn't even know that Jigs were available to fixture the trunion for welding

I didn't research this project as thouroughly as I usually do, it was just sort of an impulse buy. but hey for 450 out the door (including shipping and DROS, It isn't too bad. If I sell off the stuff I'm not going to use the cost becomes really decent.

[ptoguy2002]

I dunno, wise man once told me you can't polish a turd.

Correction:
You CAN polish a turd, but its still sh** on the inside.

Edit: OK, josh beat me to it.

[ptoguy2002]

It should weld in without any problems. OD is the same for both. However, I'm pretty sure you'll end up having to shorten the cocking extension on the bolt carrier to allow it to fit in the shorter MP5 tube.

It will weld in, but it won't work.
The .308 has longer travel of the action than a .40, so the slot won't be long enough. The charging handle also cams open the rollers when you rotate it against the plug at the end of the cocking tube (not on MP5), which does not happen on pistol cal HKs.

HK G3 on top, MP5/40 on bottom
Note difference in lenth of slot.

[ptoguy2002]

AJAX, I have a welding fixture for the cocking tube and MIG and TIG welder at your disposal anytime as usual. Oh yea and a lathe to for separating the tube from the stub. LMK.

Fedup, what does your fixture look like?
I've just got a rod that fits tight that runs down the length of it to align it.

You don't have a jig for bending ORF flats, do you?

[AJAX22]

It will weld in, but it won't work.
The .308 has longer travel of the action than a .40, so the slot won't be long enough. The charging handle also cams open the rollers when you rotate it against the plug at the end of the cocking tube (not on MP5), which does not happen on pistol cal HKs.

HK G3 on top, MP5/40 on bottom
Note difference in lenth of slot.

Does trimming the bolt carrier down reduce the length required for the cocking slot?

How are the HK51 manufacturers able to cut the system down to the point where they can use HK MP5 furniture on the firearms?

Will a HK33 cocking tube work with mp5 furniture?

How can I trim it down that short and make it work?

[ptoguy2002]

I havn't done a 51 (YET), so really can't give you detailed info on dims, but I think it varies a lot based on who built it.

Trimming the bolt carrier is really independent of the length of the slot. The length of the slot is based on the length of the action, the length of movement needed for the gun to cycle and feed. I would imagine that you can reduce it a little, but not a lot, not enough to use an MP5 tube. The cutting down of the bolt carrier is done just to make it shorter. As far as cutting this down, you need to be real careful with the dims. The HK/Cetme charging handle actually does something when you open it, its not folded down just to make it slimmer. As you open it, levers itself against the cocking tube to provide leverage to initially unlock the rollers. Therefore the length is important. Too short and the charging handle cocking tube support won't touch the carrier as you open the handle. Too long, and the carrier will slam into the cocking tube support as it goes forward, instead of stopping when the rollers engage the trunnion all the way.

I've never built one (yet) (again) but I would not cut the bolt carrier down until the whole thing is welded together. Then you can conservatively cut it down, then take a little off at a time and test fit until its right.

[ptoguy2002]

Various pictures robbed from others on the internet.
Notice the difference in how far back the slot goes, compared to the front of the mag well. Some go farther back than others. I think that some builders cut out a section of the receiver so the tube will slide and be farther back. Others just cut a new slot in the front of the receiver.

[AJAX22]

Is the camming action nececary to the function of the gun? I don't mind just giving it a hard yank.

I'm starting to get p.o'd at the arisoft guys... they seem to be kitbashing these things togeather and the pics get mixed up on the web...

Here is a pic with what appears to be a MP5 charging tube on a G3 receiver.



I'm having a heckuva time figuring out dimensions, I'd prefer not to hve to send it out for work (although RDTS looks like they do beautifull work)

[ke6guj]

http://vectorarms.com/shop/index.php...roducts_id=233 has a nice pic of a "factory" 51 receiver and you can see how the cocking groove is extended back into the receiver.

[Josh]

Is the camming action nececary to the function of the gun? I don't mind just giving it a hard yank.

I'm starting to get p.o'd at the arisoft guys... they seem to be kitbashing these things togeather and the pics get mixed up on the web...

Here is a pic with what appears to be a MP5 charging tube on a G3 receiver.



I'm having a heckuva time figuring out dimensions, I'd prefer not to hve to send it out for work (although RDTS looks like they do beautifull work)

if you can charge the gun without the camming action then no. But i cant really see how it would be practical to use the rifle without it. Some people can barely use my rifle with the levered handle.

Have you tried posting this question on HKpro.com ?

[ptoguy2002]

[AJAX22]

That'll work, that'll work just fine

my kit will show up on wednesday so I can probably start paperwork on the receiver on saturday or sunday...

what would it take to switch the CETME rear sight for an HK style drum?

[ptoguy2002]

Is the camming action nececary to the function of the gun? I don't mind just giving it a hard yank.

I'm starting to get p.o'd at the arisoft guys... they seem to be kitbashing these things togeather and the pics get mixed up on the web...

Here is a pic with what appears to be a MP5 charging tube on a G3 receiver.



I'm having a heckuva time figuring out dimensions, I'd prefer not to hve to send it out for work (although RDTS looks like they do beautifull work)

Definitely airsoft.

For what it would cost you for a custom build by someone like RDTS, you could probably get a whole new one (or at least most of one) from Vector.

Here is a real 51K: