Hk Mp5 mandrel

[tnixon44]

I was looking at the Mp5 armorers instruction manual and it list a straightening mandrel for the reciver.....I just rolled my reciver flat and would sure like to use this tool. Anyone know of one?

[texlurch]

Pick up a bolt carrier for a CETME, add .010 shims to the shoulders and the cocking tube, and square your rails with the stock CETME dimensions. Should be perfect.

apexgunparts.com has them for like $35

[HKEsq]

Right now I'm making my own. I ordered a length of 1-9/16" cold rolled and also a longer length of 3/4" cold rolled. I am milling the 1-9/16" section to correspond with the rails and to allow the 3/4 rod to be welded on top. Then weld both together. 1-9/16" is 1.05625." I don't have my notes in front of me and don't recall the exact diameter of an HK trunion or bolt carrier, but this is ever so slightly larger. The idea is that the mandrel can be pushed through the rolled flat to bring everything to spec. I am wondering if its also possible to slightly reform the rounded ORF G3 rails by tightening down on the mandrel with two pieces of square stock (from the sides)...?

With any luck I'll finish this little implement tonight... Has anyone tried making such a tool before?

I had not thought of using an old carrier with shims, but that would obviously work as well.

[texlurch]

Correct me if I'm wrong, but aren't the HK receivers pretty much the same internal dimensions? I mean between a G3 and MP5 and 93..

Here are numbers from an ongoing project on another forum:



Rail squaring and pinching the top down around the cocking tube



He made the mandrel from scratch, I am using a couple CETME carriers welded together with a 20 mm drill rod on top. 3/4 is just a hair too small. Use a piece of 1/4 inch flat plate, narrowed slightly, to form the rail channels.

[HKEsq]

Thanks texlurch for that very informative post. I'll use those charts to do my machining. I see why you are saying the 3/4" is too small and I'm going to think about how to address it. One relatively easy fix might be to mount the 3/4" rod just a little "high" so that the "pinch" dimension is a little wider. (?)

All the specs are the same -- or at least, my 91 and 93 receivers are the same and I saw someone's measurements for an MP5 receiver and it was exactly in-line as well.

[JP223]

wow...sounds great! I need to make one.

[trek45]

http://www.hkparts.net/shop/pc/viewP...8&idcategory=0

[HKEsq]

http://www.hkparts.net/shop/pc/viewP...8&idcategory=0

How much is that thing? It looks great but I'm guessing it's pretty pricey...... I spent $15 for my steel.

[tnixon44]

I'll bet you!!! It would be cost a lot less to have one machined than to buy from Hkparts.net.....Thanks for all the help!!! Tom

[david795]

tnixon, I do not know if you still need it. But the armorer manual can be found here: http://gunmanuals.net/