My late Brother-in Law left me an unfired Colt SP1 AR 15.  At a gunshow I found a pristine Colt CAR SP1 16" shorty upper that now lives on top of the Colt lower.  

  Not really able to sell it for sentimental reasons, I found myself with an extra Colt SP-1 upper .     It seemed a waste to have it sitting around so I built up a Rock River Arms lower and put the original 20" SP1 upper on it with an off-set small/large hole conversion pin. I'm not really hapy with the conversion pins as it just doesn't open easy and seems to fit  oddly.

  I would like to get a 16" flat top M4gery type upper with a vertical grip of some sort for the RRA and maybe down the road find a lower that would be a better fit for the Colt 20 inch upper.

Two questions; Based on the fact that I'm not going to use these professionally, just target shooting and home defense.

Who makes a  reasonably priced 16" flat top with provision for a vertical handgrip ?>

Who makes an old-school A1 AR-15 lower that works with the original SP1 type pins?.  


 Thanks in advance.




 

Quoted: Who makes an old-school A1 AR-15 lower that works with the original SP1 type pins?.

You'll have to get another large-hole Colt lower, as you have no other options.

See how they multiply? You bought an extra upper, now it needs a lower. Just like rabbits, I say.