SP5 lower switch out?

[Valmet]

Considering purchasing an HK SP5 and making it into an SBR- however if want to swap out the plastic fantastic polymer lower for a metal one and am wondering how easily this would be? Any info is appreciated, merry Xmas gents.

 

[Davisdonl]

Good day,

I have been trying to think through the same question . I am wanting to do some things with a SP5L.