I'm looking at purchasing an SP1 upper. It states that it's a "small hole" upper. What does that mean? Will it work with any lower receiver?
THanks, Mark
Posted: 5/1/2005 11:07:23 AM EDT
[#1]
That means it will work with all standard lower receivers. It will not work (without and adaptor) with the older Colt lowers that had a large screw pin instead of the front push pin.
