Gathering stuff for my first build. I have just about everything except a stock and tube.
I have a Stag lower receiver and LPK, I need the mil spec tube for a M4 type stock. Anyone know a good vendor that has these in stock?
Any potential problems putting a collapsible stock on a 20" gun? I assume I'd use the carbine buffer and spring.  
Another dumb question I have is the handguards. I have an M16A1 upper on the way, I like the old style sights. Will round handguards fit (drop in) on an upper that came with the old style triangular ones?

TIA. Shoot straight, John.

I had some of the same concerns with my new "20 colt barrel I got.

I got a new set of round rifle handguards from a chap here, and they did fit the triangular hand guard retainer, they were designed with tabs on the front for both types of retainers. worked out great.

I also, want to set mine up with a collapsible stock too.  I dont think it will matter,should be fine.....

also.....

why mess around with a big wait for the tube. in the EE here several people had mil spec tubes for sale. then you can get it in less than a week.

Thanks for the info! I'll check out the EE.

The buffer and spring you will need depends on the buffer tube and stock you end up with.  Most collapsable stocks I see do use carbine buffers and springs.  I can't say I know of one that doesn't, but I've never looked for one...

If you want everything together, some websites sell complete stock kits.  Whcih include the stock, buffer tube, castle nut, spring and buffer together.  I bought my Magpul CTR stock like this and it was only an extra $50 (IIRC) to get the kit over buying the stock by itself.

Done deal. Found a new complete kit on the EE. All new Stag with the tube, nut, stock, etc. Might need to pick up the wrench for it or maybe after I see the stuff can fab something to work. The wrench is just a piece of stamped metal right?