I've seen a couple of these purported "Sistema" Colts that were not Argentina guns at all but were actually genuine Colts.
Prior to 1927, Colt manufactured 1911's and 1911-A1's for the Argentina government in its Hartford, CT plant and these guns bare the normal rampant Colt logo and Hartford address on the left side of the slide and the Argentina crest and inscriptions on the right side.
In 1927 Colt sold the tooling and the manufacturing license rights to the Argentina government and actually set up the plant in Argentina for them. The guns made in Argentina, after 1927, were actually made on Colt machinery and bare the Argentine crest and description on the right side of the slide and the just initials D.G.F.M.A.P. or F.M.A.P. (Fabrica Militar de Armas Portalias) on the left side.
The pre-1927 guns have significantly more collectors value but not a lot of people are even aware of the difference. You might get lucky and draw one of these.
Mechanically, and functionally, there is absolutely no difference in the guns and all of the parts interchange freely with every other standard 1911 part ever made. At least every one I have ever run across. I've got three of the "Sister" Colts, one pre-1927 and two Argentina made guns, and the only difference is a little bit rougher finish and a few more tools marks on the Argentina made examples.
Happy shooting; Doug