PM 63 conversion to closed-bolt semi auto?

[dakota.potts]

APEX lists these PM63 parts kits going for a pretty decent price, right around $100, here

http://www.apexgunparts.com/review/product/list/id/5142/category/60/

There are also barrels available, at a somewhat steep price.

The problem is the bolt.

The PM63 is a Polish submachine gun chambered in 9mm Makarov. It feeds from 15 and 25 round magazines in the grip of the gun and is a select-fire, open-bolt mechanism. Obviously, this is an issue. The ATF considers anything open bolt to essentially be a machine gun as it is too easy to convert into a machine gun. I disagree, but it is what it is for now.

There is a pretty long thread over on AKFiles with some discussion on various things about restoring them. The bolt is pretty much the last major hurdle it seems. The bolt is pretty much attached to the slide and rides with it during travel. It has a fixed firing pin. The general consensus right now is that the fixed firing pin can be drilled out and replaced with a longer, spring-loaded firing pin that's fired by a striker or linear hammer system. The biggest difficulty is in the fire control group, since the slide is so small and has such little space to operate. A member on Weapons Guild has a somewhat functioning prototype using a modified fire control group from an equally obscure firearm, the CZ 26. His puts the trigger at the very rear of the gun, behind the bolt. It is firing, but right now he's got the trigger there instead of in the grip frame so he has to work up a trigger linkage.

A company called Pioneer Arms is importing them in their semi-automatic form, and they have this 3D CAD drawing of their mechanism. However, I'm not really sure what to take from it.

Anybody have any ideas on what it would take to get one of these guys running legally?

 

[Dixie Gunsmithing]

It's a modified form of the Browning two hook trigger system, similar to what is in an AR. They just set the trigger forward, and ran a link back to the sear/disconnector hook set. The red piece sticking up mid-way is the hammer, and you can see the disconnector notch on the top end.

 

[dakota.potts]

I really need to get one of these parts kits in my hands to look at and dissect, but that's a couple paychecks away. The original is an open bolt with reciprocating slide and bolt, so fitting the new parts in there is going to take some work.

So, I guess the steps would be

1) Mill out original slot from original firing pin
2) Create new, longer (spring loaded) firing pin
3) Install new semi auto fire control group (I'm hoping I can use an existing mechanism for this, rather than creating brand new parts) with disconnector using a striker or linear hammer system
4) Rig up a transfer bar for the trigger.
5) Try to figure out how to keep the bolt from returning to rear position. I'm assuming the slide has a sear catch or foot somewhere that just needs to be removed.

I've heard of some people working with Glock and CZ 26 parts. I'm following their progress closely.

I might just give this a try myself. It's a big project. I probably wouldn't even think about it if I didn't have a full machining/gunsmithing lab available at school.

 

[Dixie Gunsmithing]

It looks to me that they have a new type of safety, too. That is, if the colored parts are all part of the kit.

The yellow link bar, goes back to a green lever, which is really part of the sear and sear hook (brown), and makes it rock forward, when the trigger is pulled. The disconnector hook is behind the sear, colored blue, and is spring loaded, so you don't feel trigger bounce. It has a two piece trigger, with a lever that comes out, which attaches to the link.

The hammer, (red), is about the same design as those in an AR. Both the disconnector notch, and the sear notch, are on the top rear tip.

The bolt will most definitely have to be modified, if it has a fixed firing pin, which fires from an open bolt. I think I remember this gun, as a full auto, and it worked similar to the grease gun, and others. Maybe they will have a new bolt assembly for it?