Wanting to buy a Colt dedicated 9MM but see differences in price along the line. Is one "better" than another or more collectable /
I'd like a nice shooter but also something a little different therefore collectable.
Thanks

I've kind of narrowed it to between a 6450 LEO marked and a pre-ban.

Ideally the upper could  eventually be adapted to a registered class 3 lower.

I have a 6450 with the fixed upper.

If I was going to buy another Colt 9mm I would certainly spring for the Colt 6951 (I think that is the 9mm version with a flat top).

The reason is optics.  The 9mm Colt is an absolute hoot to shoot at steel plates at pistol distances.  It would be so much better with optics, though.

The 6450 has A1 sights, which mean you use an A1 tool to adjust the sights or ironically a 5.56mm round.

Oh, and buy Metalform magazines.  They work and were the original OEM supplier to Colt.  Insist on Metalform!

The 6951 is the best choice.
The bolt is ramped, the hammer is M16 style, the trigger pins are better and the flattop is the only way to go.

Colt has not made a collectable AR15 in many years.