Currently I have the M4 but wanted to try out the CAR type as well since I have an A1 upper and it would look more correct on my gun.  I was thinking it would be nice if I could just slide off my M4 stock right off of the buffer tube and then slide on my new CAR stock without having to dissasemble the stock assembly because I can remember the last time I installed and it was a pain in the ass.  The buffer tube in question is a 6-position while the CAR stock has the 4-position,  If they are the same length it shouldn't matter, and I can use them interchangeably right?

Jiggz

They are not the same length.  I tried already.  With the stock all the way closed, the buffer tube will protrude out the back.  However, if  you leave the stock in the 3rd or longer position, you won't see the buffer tube.

A mil-spec stock will fit the best but a little larger commercial stock should fit just a little more rattle I would assume.I know it wont work reversed mil stock to larger tube.

The above two answers don't cover the differences between Colt and other mil spec assys, and the usual aftermarket pieces, like Bushmaster, Rock River, etc., and the answer to your question depends a great deal on wht type you have on your rifle currently, and wht type you're trying to mount.

The Colt and other milspec types all use the same length tube, though the number of detent hole my vary. A current type M4 butt will therefor be longer than the tube, so if your piece has that characteristic, it's a milspec type. If the tube on your M4 stock comes to the end of the butt piece when retracted, it's a commercial unit.

If it is a commercial unit, and the earlier type you bought is also an aftermarket unit, then Doc Holiday's comments are accurate, and the stock piece will go on the tube, but the tube will stick out the back in full retraction. If the 6 position tube is milspec, and the aftermarket unit is commercial, the stock piece will fit w/o sticking out the back but the stock will be loose and rattle.

Finally, if the replacement unit is Colt, and the 6 position tube is commercial, the stock piece won't fit on the tube.

I think that covers all the possibilities, though I do wonder why you just didn't try it out for yourself

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Shamayim already nailed it, and like he said, it depends on what you have.


I take a CMT CAR stock off and replace it with a Colt M4 stock all the time.