I have an SP1 lower with a large hole A2 colt 16in upper/lightweight barrel bolted on. My question is this...will the latest 4 position model Rock River Arms collapsible stock work with this set up....I believe it should, just want to make sure before I buy it?

Any help would be appreciated.

Thanks,

Jim

It sure will.  Just do yourself a favor and buy mil spec/Colt, in case you want to use Vltor or maybe later, Crane stock.  Bushmaster and RRA tubes are both wider in the rail section to be incompatible with Colt, Vltor and other mil spec stocks.

Thanks Duffy, but I'm pretty slow tonight and want to make sure I understand you correctly.

You're saying do not buy the "newest" collapsible sock offering from RRA and buy Colt milspec instead?  The newest (I believe its 6 positions??) RRA collapsible is not milspec?  The guy selling it at the show here said RRA is supplying them for the M4s??
 
Thanks again for your reply, just want to make sure to avoid reliability issues when I get this carbine together.

Jim

Whiskey, this topic came up quite a bit when the Vltor stocks came out.  The carbine version will not work with anything but Colt tubes.  Colt tubes aren't marked, I doubt if Colt makes them, most likely subcontracted to others like LMT or others.
I have the RRA, Colt and Bushmaster stocks and extension tubes, if you put RRA/Bushy stocks on the Colt tube they'll rattle, because the rail sections are wider on the stocks.  If you try to put a Colt or Vltor stock on an RRA or Bushy tube, it will not go in at all.
Colt's is 4 position only.  Unless RRA changed its tube dimensions, it's not milspec.  I see ads all the time touting that but only Colt's is.  Wes at [url]www.mstn.biz[/url] will be selling these tubes, I suggest you get it from him.  I got a Colt tube from Brownells for $120, Wes' units are made by the same folks that make them for Colt and go for much less.

The top is RRA, bottom is Colt, complete with their respective tubes.  RRA/Bushy sling loop swivels, Colt's is fixed.  The section immediately ahead of the release lever chevron on the Colt is not curved but perpendicular to the stock.  Colt's material is also better, the checkering on the butt pad is sharper.  The Colt tube is better made as well, without the machine marks still left visible on the RRA/Bushy units.
[img]www.imagestation.com/picture/sraid69/p66518ade3b485a5b3ef4cf4144b91fe0/fba8f7d5.jpg[/img]

Ok, cool....thanks for your help.  I'll call wes and get one from him.

Jim