Just received my approved form1 & stamp from the BATF for a registered SBR & completed the 607 carbine shown here today. I know there's a few "retro heads" here, the 607 was actually the 2nd Colt "carbine" but the 1st using a retractable stock, although not the type commonly known/seen, the 1st "carbine", the 605 was actually a rifle w/barrel cut to 15.3" but using standard rifle furniture, the 605 replica pictured here has an original 65 era M VP marked barrel cut to 15.3" & the FH is permanently pinned to get legal 16" length, the 607 used a 10" barrel w/either a standard 3 prong FH or the later 3.5" moderator and a retractable 2 position stock made from a modified rifle stock w/a completely different retractable mounting system than the later carbines. Both of these models saw limited use in the VietNam war prior to the introduction of the more common & better known AirForce GAU series & Army XM177 series. The 607 uses a NoDak XM16E1 partial fence lower, Colt A1 upper modfied to very early configuration, original early Colt chrome 603 bolt carrier, bolt & parts, original Colt fire control group parts modified to legal semi only configuration, a my65pan reproduction 607 stock set w/lower modified & stock installed as per the originals, a WA-Tom 607 handguard set & a Colt 16" 1/12 carbine barrel from an SP1 carbine which was cut to 10", had the front sight base smoothed, markings removed, bayonet lug removed & drain hole under sight post removed to duplicate the original 607 configuration, all the barrel work was done by heatNbeat of ar15.com. The rifle is fitted w/a cut down A1 grip which is seen in some pics of these rifles but they were more commonly seen w/standard A1 grips. For anyone interested in more pics &/or info on the 605 or 607 here's links to albums w/many pics of each:
605 PICS HERE: http://imageevent.com/willyp/firearm...6/coltmodel605
http://imageevent.com/willyp/firearm...6/coltmodel607Click image for larger version. 

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ID:	376674 Model 605
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ID:	376676Model 605 left
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ID:	376677Model 607
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ID:	376678Model 607 stock latch
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ID:	376679Model 607 stock extended
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ID:	376680Model 607 components prior to assembly