Did Colt make the SP1 style unblocked lower so that LEO's had the option of using a DIAS ?
Does Colt also make a large pin A1 hammer, sear and trigger otherwise why bother?
I used to have a regular Colt model R6551 Sporter Target Model that I bought new in 1991, blue label box, without the steel sear block and the lower was cut like the old SP1, large 0.170 FCG pins, with magwell fence, it was similar to the R6550 AR-15A2 Gov't Model rifle without a bayonet lug.
That same year '91 I also bought a new Colt model R6530 Sporter Lightweight carbine, also blue label box with steel sear block and large FCG pins, mine had a magwell fence but I had seen some other same model without any magwell fence.
I don't remember if they had large size pivot pins, but it probably does with most all the AR models in the early 1990s, they had a flathead screw head pivot pins.
Back in 2005 I bought a Colt LPK 0.170 large pins from SAW and it had a notched top semi-auto type hammer.
Also I have an AR6721 A3 Tactical carbine made in 2002, LE marked, with large 0.170 size pins and it have the same notched semi-auto type hammer same as the LPK I bought in 2005.
I had seen SAW sells a large 0.170 pin semi-auto type I with rounded upper corner (no notch) and no M16 tail, ref. Product ID : SA21175.