Re: MR1 accessories
I think he means that he doesn't want the clamping feedneck to be at a 45* angle which would make the hopper at a 45*. I got a rap4 one cheap on eBay a while ago. It's well worth it. They're pretty much all the same so it doesn't really matter which one you get.
I'm not saying you need to buy any from this search but is this what you are looking for?
Spyder Classic Single Trigger Frame
M16/AR15 Carry Handle
PCS MX-16 Barrel and Shroud
Rap4 Clamping Feedneck
6 Point Collapsible Stock
M16/AR15 Recoil Pad
M16/AR15 30rd Magazine
Custom Milled Side Cocking Slot by ACP
ACP Slim Delrin Striker with Side Cocking Hole
Spyder Classic Side Cocking Knob