Welcome (again) to the site!!! :wink:
A SP89 can be tough to add a vertical to unless you go to a AOW. Most HK SP89s were imported after 1989, so to go the SBR route would require US made parts to be added. A US clone would be easier to do a SBR.I remember in the early 90's watching films like Die Hard and loving the action scenes with MP5's but one film really got my childhood interest peaked and I've wanted one ever since and that film was Under Siege. (9:50 - 10:15) My love affair with the MP5K started and its has been there to this say. I hope to afford a SP89 down the road and put that k grip on it If anyone lives in the North Texas area and would be willing to let me shoot a K model Ill bring all the ammo you want!
Steven Seagal - UNDER SIEGE (1992) Part 5 - YouTube
Right now I only own one HK clone but that will change when money frees up. Glad I decided to walk into my local fun shop a few weeks back
As I recall the Hanns character actually reads the note written on the first "terrorist" that was killed. I believe it read "Now I have a machinegun, Ho Ho, Ho". Good luck with your MP5K look alike project.I remember when John Mc Lane said "now I have a submachine gun" (Die hard), and feel the same when I got my MP5.