Sounds like you were looking at a 'Hero' Pulse Rifle, made from the airsoft Thompson and real Spas cage.
Others on here have tried (and failed) to just replace the G&P plastic grenade launcher with the real Spas cage.
What you could do is just replace the fake shotgun shell in the G&P with a metal one.
There are different ones on sale in the PX from time to time. Some people may still have spares, so you may want to post in there.
If you're going the Hero route, Phil S. has a large amount of metal and resin parts:
Quote:
Metal Pulse Rifle Parts
Aluminum receiver block (welded to receiver)
Aluminum receiver (milled)
Aluminum receiver (not milled)
Grenade launcher front block
Rear shroud connector block
Front shroud connector block
Front aluminum shroud plate (small trapezoid)
Rear aluminum shroud plate (large trapezoid)
Steel connector plate for shotgun pump (w/ welding to Remington part)
Delrin insulator block for battery connectors
Rear shroud strap and connector block
Far rear aluminum 1” strap
Aluminum barrel
Steel triangle for barrel front
Aluminum v-shaped barrel shroud
Steel buttstock
Aluminum triangles for shroud (pair)
Miscellaneous screws
Metal Totals (milled receiver w/ front block)
Metal Totals (non-milled receiver w/ front block)
Resin Pulse Rifle Parts
Grip
Magazine insert
Magazine bottom
Magazine bottom shroud tabs (pair)
Shroud
Shroud halves (2) and hardware
Digital Counter
Electronics
Magazine (wired)
Prepared magazine
All Parts (assembly consultation not included)
Metal, Resin, Shroud Totals (milled receiver w/ front block)
Metal, Resin, Shroud Totals (non-milled receiver w/ front block)
Contact him via his e-mail addy:
phil@steinschneider.com for a current price list.
Matsuo on here also has various metal and resin parts from time to time.
Other parts, such as the metal Spas cage can also be found the the PX section.
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