I've ordered a complete upper with an 18" barrel and rifle length gas tube.  I have looked for but can not find information on what kind of stock and or buffer system I need.  Could someone point me in the right direction for this information?  Many thanks.  Denis

Ive got an 18" with a carbine tube, and heavy buffer.  Works beautifully

Heavy buffer wouldn’t cycle in mine. I will try a carbine buffer, but I’m not sure it will work either. I suspect my gas block may not be on right. Oh yea, it may be that I was shooting Tula more than the buffer.

I use a standard carbine buffer with my 18” rifle length...works perfectly.

I bought an upper from PSA about a year and half back.  Had issues with my favorite load (works in 10 or 12 other AR15's but was short stroking in that one).  Checked the gas port/gas block alignment and it was okay.  Finally opened up the port in the barrel just a tad and it runs great now.

Standard carbine buffer in mine, very smooth

I suggest using a SLR Sentry Adjustable Gas Block and a carbine buffer. Turn the adjustment screw all the way counter clockwise. Load 1 round at a time with a magazine seated. After each shot, turn the adjustment screw one click clockwise until the bolt fails to lock back when fired. Then turn 2 clicks counter-clockwise and you are done. If, with the adjustment screw turned all the way counter-clockwise, the bolt will not reliably lock back then you will have to enlarge the gas port. I do this one or two number drill size at a time. Repeat the above test with each enlargement of the gas port unil you get 100% reliable bolt lock back on an empty mag.

The only deviation I do to this myself is that I have standardized on Taccom ultra light buffer and Tubbs flat wire buffer spring on all builds from 10.5" pistols to 20" rifles.

VLTOR A5 with a Sprinco Green.

Carbine stock and carbine weight buffer here too

what caliber is it? if its a 5.56  all you need is a regular carbine spring and buffer. you can put any buttstock on it that you like. most of the time you buy a kit that comes with all the buffer tube parts and a stock,
I have the normal magpul stock on my 1st ar and a rogers super stoc on my latest one im building now.
both are 18" .223 wylde  mid length black hole weaponry barrels.

Let's start from the beginning...

Barrel length and gas system are independent from the buffer system and type of stock. Therefore, there is no definitive answer for your question.

There are 3 basic buffer systems out there; Rifle, Carbine, and Vltor A5. There are a few other exotics, but let's stick with these for now.

The type of buffer system you need is primarily defined by the type of stock you intend to use.

Are you planning on running a fixed stock, such as an A1, A2, Magpul PRS, or Magpul MOE fixed rifle stock? If so, then you will need a rifle length buffer tube, spring, and buffer.

Are you planning on using an adjustable stock, such as an M4 stock; Magpul MOE, CTS, STR, SL, ACS, or ACS-L; B5 Bravo or SOPMOD; Vltor EMod or IMod; etc...? For these, you will need a carbine length buffer tube, spring, and buffer. There are plenty of options to choose from, and almost all use the same 6-position carbine buffer tube (receiver extension). There is also a Magpul fixed carbine stock that uses a standard carbine buffer tube.

The Vltor A5 system is more of a hybrid carbine buffer system. It uses a special buffer tube that is 3/4" longer than the standard carbine buffer tube, and has 7 positions instead of 6. The added length works well with the Vltor EMod and Magpul ACS/ACS-L stocks. It also uses a special 4" long heavy buffer, and a rifle buffer spring. Again, it's a hybrid system that only works with specific components. The Magpul UBR Gen. 2 stock is also compatible with the Vltor A5 heavy buffer, but uses it's own proprietary receiver extension.

There are a few other exotic options to choose from, but this covers the 3 basic categories.

Separate from the choice of buffer system and stock is the issue of buffer weight. I'd recommend starting with the standard buffer weight and spring for whichever stock you choose, and then start looking into heavy buffers like an H2 or H3 buffer only if needed. There are also lots of different spring choices on the market, but again, just start with the basic version and go from there.

I know that it seems overwhelming due to the incredible number of choices and options available, but it really boils down to the three categories mentioned above. You just need to decide if you want a fixed stock or an adjustable stock, and go from there.

I hope this helps!

I have a standard carbine buffer in mine and the only problem that I had was the first time shooting it would cycle properly. It would eject the round but it wouldn’t pick up the next round. I used pmags and test them in another rifle and they work flawlessly. The only thing I could think it was is everything breaking in and getting oiled up. Everything works now and it is smooth as can be.

Thank you to all for the information.  The upper I've ordered is a 223 Wylde 18" barrel with a rifle length gas tube.  The stock I'm interested in is a Magpul ACS Carbine Stock.  From what I'm reading is that I should start with the buffer and spring with the stock and evaluate how it functions.  Since this is the first AR that I'm piecing together I'm trying to understand possible problems before I make the mistakes.

Thanks,
Denis

What you need is a standard 6-position carbine buffer tube (also called a receiver extension), a carbine buffer spring, and a standard carbine buffer (3 oz).

Something like this would be a good place to start:

Mil-Spec Stock Hardware Kit

Primary Arms also has the ACS stock on sale at the moment, and they are a great vendor to deal with!

ACS Carbine Stock, Mil-Spec

One thing to watch out for is that there are two different "sizes" of carbine buffer tubes and stocks; Mil-Spec & Commercial. Avoid anything labeled as a Commercial stock, and stick with Mil-Spec. It's by far the more common and readily available type.

this. carbine tube with plain jane spring and a 5oz steel pistol buffer on mine. recoils like a squirt gun. its awesome.

18” barrel will rifle gas tube, usgi rifle buffer & spring here.

Zero problems, smooth shooting.

This is timely. This is my next build . I won a Geissele rail and it needs a barrel .

I've got a spikes t2 buffer in mine and it works very well (~heavy buffer).  Shilen barrel, slr sentry 7, rifle gas.