I ended up making this for my current project.  Share it far and wide.

These rods replace the factory components from the collapsible stock, bringing an MPX-pistol up to 29.5" in compliance with state law.

The fully extended length is 29.5" (put this on your form 1 for OAL), as measured to the front of the barrel (NOT the removable muzzle device).

The fully collapsed length is about a half inch shorter than the fully extended length on the factory components.  DO NOT change the position of that rearmost notch, or the rods will smack into the upper receiver sides.

You could put the other notches wherever you like.  I used 1" increments, but you could use 3/4" or anything else, so long as they're the same for both rods.


Still time to get your Form 1 in before 41P if you've been on the fence to buy an MPX, waiting for a MD-legal solution.

Someone make me some?

I was trying to figure this out a month ago, but wanted to make the actual stock move on the rails as well.

What ever happened to the unconstitutional ruling on the MD law?

I'll be making a set for myself at some point.

The amount of extra work required to make two sets once I've already got the mill set up will be minimal, so...

Maybe if you ask nicely...  


No timeline on this, and I won't even make a formal promise, but I'll make it a point to buy enough material to do a few sets and, assuming I have enough time (I'm borrowing machine time, which costs me beer), I'll try to make a spare set or two.  It will be at least two months.


Put 6.5" barrel length and 29.5" OAL on your Form 1 and submit it so you get in before the deadline.  Even if I totally fail you and you have to send this drawing to a machine shop, it won't cost you that much.  You'll spend much more for the stock itself.  The rods swap out easily with some hex keys and a pin punch.

New post because I'm not sure what you mean.

Are you saying the rear stock pad/plate unit should slide on the rails?  The stock unit is an injection molded polymer piece, and if you drilled out the rear of the rod cups it might not stay strong enough.  That, and, the rod cups are a pretty tight fit on purpose.  It wouldn't slide very easily.


The buttplate does slide off very easily by the use of a vertical dovetail.  The alternative idea (not mine, but one I was working to design) was to have a replaceable buttpad which hinged like an M14 - literally, a shoulder thing that goes up.

The longer length would make 29.5" with it flipped up, and flipped down obviously the stock would behave as normal.

Even better, the rear pad is very quick to remove or attach, so traveling from state to state you could convert to stock configuration in seconds with no tools, versus this solution which requires maybe ten minutes or so and a few simple tools.

The problem with replacing the buttpad is:
1) Many more machining steps.
2) Replacing the plastic buttplate with something metallic, with a hinge, and extra material... adds a lot more weight than 10" of 7/16" round stock.
3) Much higher material cost, involving a lot more components.

So, can be done?  Sure.

But ultimately I thought this was the easiest and cheapest way to skin the cat.  Sure, it functionally makes a collapsible stock non-collapsible, but it's still going to be a pretty compact rifle.

Pretty please endow me with your rod so as I may bust off.....