got 1. Tnx all.

Did your CAR stock not come with a buffer tube?

Most dealers that sell stocks sell tubes. Look on this site in the equipment exchange. Or find a dealer that sells the CMT stocks. The CMT tubes are inexpensive and compatible with Colt.

I bought the Duostock. They only sell stocks to put on a Car. I tried it on a Bushi tube and it did not work well, very tight fit.

As you're learning there are two different size tubes. Mil-spec and commercial. Colt, LMT, CMT and Vltor use the slightly smaller mil-spec dia. Everybody else, including Bushmaster & RRA use the slightly larger commercial dimension.

I have no clue on why to two dimensions exist. But like Lancelot said, find somebody who's selling CMT stocks and see if they have just the tube. CMT is top quality that is sold for a reasonable price.

I would start with John (Tecnik) at Tactical Solutions. He's got good prices, that include shipping, and is honest as the day is long.

Quoted: I bought the Duostock. They only sell stocks to put on a Car. I tried it on a Bushi tube and it did not work well, very tight fit.

If it fit al all, even tightly, a Colt or other milspec tube is likely to give you a very loose fit. My Colt butt piece won't even begin to go over a commercial spec tube.

Grant at G&R sells the 6 position mil-spec CMT tube for $40, I know because I may or may not need one for my next lower, depending on which stock I go with from my parts bin, LMT M4 (need tube), CAR (non milspec DPMS but have tube), or fixed A1 or A2.