09 April 2017, 01:30
Barry FosterColt AR15
Here's my 1975 Colt SP1,great shooting rifle.
09 April 2017, 12:18
p dog shooterHad one just like it back im the 70s sold it.
10 April 2017, 03:33
Grizzly AdamsLooks like the one with the special pin so you couldn't match an M 16 lower to an SP upper.Logic always escaped me.
10 April 2017, 18:27
Barry FosterColt changed the front pin design because the pin was said to be easily lost when tearing down the gun to clean it in the field.
12 April 2017, 15:56
Samuel_HoggsonIt wasn't logic. In '63 Colt submitted a plan that included nine modifications to the service rifle. The Treasury Dept response stipulated one more change. The front pin needed to be offset.
Most original stipulations became unnecessary when ATF focus shifted to internal receiver machining (the shelf).
The M16A1/SP1 configuration is still my favorite.