Designing a pump action 9mm bullpup using Beretta CX4 Storm carbine barrel

Here in Canada CX4 is considered restricted and those who don't want to put up with PITA logistics of getting government approval for every move of their carbine usually swap out the 16" barrel for 18.5" so those 16" barrels can be had fairly cheap. I have one and it's just collecting dust so I decided to put it to a good use. If I made my own hand operated gun (be it single shot, bolt, pump or lever) it would not have the above restrictions. Also if its receiver was a bullpup from get go versus having a bullpup stock, it would be legal in Canada (bullpup conversion stocks are banned).

So I thought of using Beretta barrel in a railed aluminum upper receiver and Beretta mags in a lower receiver bent from 4130 sheet to keep things in entropy.
The pump I thought could be outfitted with just 1913 rail and operated with a user's choice of angled grip or vertical grip.

One thing I could not decide upon would be locking mechanism.
The barrel's breech end has 1911 style collars but no lug. It also has threaded collar in the middle and tapers further out towards the muzzle.
I thought of tilting bolt system as well. 9mm does not need any overkill of locking, but still has to be locked somehow. What would be the simplest and most compact locking mechanism?

Attachment 67300Attachment 67301Attachment 67302

Would a roller lock like a CZ52 work? Maybe turn it upside down and backwards so that the roller cam is on the top of bolt. Have it float about 5/16 of an inch and then start moving the bolt.

Check out weapons guild. They have tons of ideas on home built firearms. I am in the middle of a 50 bmg single shot build right now..

You could use a piece of tubing for a receiver and blow back operation (heavy bolt). Mate it to a AR15 lower for 9mm, and use a 9mm AR15 bolt (maybe just make one). Since the key aigns the bolt, you might as well put the operating spring in a tube on top. Would have to if making a bullpup anyway. 9mm barrel blanks are cheap and easy to find. At least I've seen several on evilbay lately.

AR series of rifle's are prohib's up here. Take them to the range and back,that's it. No hunting or plinking allowed.
Barrel blank's are a PIA because of export law's since you know who was voted into office.

Blow back would be semi-auto and barrel length would put it into restricted class (royal PITA to transport - have to get government permission and go only point A to point B at prescribed time and date).
Also, being semi-auto would limit its magazine capacity to 5 rounds. This has to be hand operated. I could make break action single or a bolt in a heart beat, but pump is what I am really dreaming about. If I succeed, this will be a sweet little gun.

Did you get a chance to look and think about the lock used on a CZ52? I've been thinking of using that for 9mm or .30 carbine.

look for a schematic for an IMI Timberwolf.