Garvin, I tried to reply to your message but you inbox is full. Feel free to use the pictures for your gallery.

Interestingly going by the serial numbers mine is only two guns apart from this one you already posted.

I'll have to dig and find the Philippine mags. One model that I thought was interesting but never saw a picture of was, if memory serves (very questionable) was called a "Bonga" which was a simple pump pneumatic along the lines of the bicycle pump Benjamins. As I recall, this was the basic back woods (jungle?) air gun.
That would be interesting, you mentioned airguns designed for self-defense earlier and firearms restrictions certainly seems to drive this sort of expedient fabrication. The Caselman Air Machinegun was such a development, in the words of the designer:

"with gun prohibition perhaps staring us in the face it is nice to know you do not have to be without protection. This gun was designed with the idea that any and all guns could be banned and ammo could be illegal or unavailable, this is why we strongly urge you to have these plans. To have the security of knowing you can make a high powered automatic weapon using high pressure air………..a self sufficient alternative for home protection and defense, and also the inexpensive pleasure of machine gun shooting."