I picked up two twenty round AR magazines yesterday. Both floorplates are marked:
COLT AR-15
cal. 5.56 mm
colt's p.t. f.a. mfg. co. inc.
hartforld conn. u.s.a.
Followers are dull grey alloy.
One mag has an I over a U on the spine.
Are these USGI or SP1 mags? Are they worth the $20 each I paid?