[chevyrulz]

i'm wanting another upper for my ar15 so i can take a deer using 6.8

i plan to build it myself. i've never built an upper before but have repeatedly read/watched videos of the process. i am also quite familiar with the ar platform in general, and i have my .223 upper to reference during the build as well.

any advice on tools, problems, parts sources, etc would be most greatly appreciated. here's what i've decided are mandatory:

18" 6.8 bbl w/ good feed ramps
PRI QC brake
rifle length free float tube, possibly hogue overmolded but something cheap for sure
midlength gas system hidden under the FF tube
no FSB (front sight block) or BUIS (back up iron sight)
flattop upper, also w/ good feed ramps
all black color
probably a Falcon Menace mil/mil scope



questions:

gas block/tube recommendations to fit under the free float rifle length handguard?

cheap bbl recommendations?

twist rate?

will i have any problems (cycling issues) using my carbine gas system .223 upper and a 6.8 upper with the midlength gas system the same lower?

special tools for assembly? i am aware i'll need a vice and a receiver block, and i assume probably a pipe wrench or strap wrench of some kind as well.

did i forget any parts besides the obvious optics/optic mount/charging handle/bcg/mags?

local places to buy ammo like walmart or dicks sporting goods? or just order online?

common assembly problems?

 

[paulosantos]

If you are not in too much of a hurry, I'd get the X-Treme Barrel from AR15Performance or Titan Arms. A CMT upper receiver is a good choice because it has the M4 cuts. I'd go with a Smith Vortex or A2 Flash hider for hunting instead of the QC Brake. They are loud. Just get a low-profile gas block like the YHM and it will fit under the Handguard.

For optic mounts, check out the new ones from Burris.

 

[ArtFWTx]

If you're stuck on 18 inch barrels, you're limiting your good choices severely. 80% or more of all 6.8 barrels are 16 inches since the cartridge is very efficient. Barrel specs for current performance levels should be DMR or SPC II chamber and 1:11 or 1:12 twist. You can do okay with SPC II and 1:10 but this is as fast a twist as you want. The old SAAMI chamber and 1:9.5 twists are not recommended.

White Oak Armament makes a nice SS 18inch barrel. SPC II and 1:11
Stag makes a 20 inch SPC II and 1:11

The Xtreme upper would outperform many uppers you could build yourself, and their price is amazing. Give up 2 inches, and get a much better combination.

Don't go "cheap" on a 6.8 barrel. The cheap choices are an accident waiting to happen. You may end up with a leftover SAAMI chambered barrel, and even worse one with a 9.5 twist.

As Tim_W says... look at how much you are spending on ammo, so what's a few hundred dollars spent on a good barrel?

 

[BLACK LION]

If you want great and you want cheap, Buy Xtreme.

With the barrel you are looking at in 18" and even 16" thats 280.00 easy.

6.8 bolt = 65.00(without the carrier) 150.00 for the entire bcg

Then your upper = 100.00 or more

here you are at 500.00 and still no muzzle device-forend-gas block-charging handle-gas tube and other small parts, not to mention assembly tools and margin of error.

the extreme will run you 599.00 and its built better than most high end uppers. I tried to do what you are doing and I still spent over 750.00 easily.

 

[chevyrulz]

thanks for the advice, keep it coming!!

links to these suppliers would be most helpful.

as for barrel length, i'm not stuck on 18" per se. i just want this upper to look drastically different from my M4gery. i'd definitely be fine with 20" or longer barrel. if the cartridge was designed for the 16" bbl then i guess that's what i'll get.

also, my most important question:

will i have any problems (cycling issues) using my carbine gas system .223 upper and a 6.8 upper with the midlength gas system on the same lower?

 

[BLACK LION]

you may want to employ and h buffer and superior shooting systems flatwire recoil spring.

 

[ArtFWTx]

http://www.ar15performance.com/ for Xtreme uppers.

http://global-tactical.com/ for Custom White Oak Armament 6.8 barrels.

http://www.whiteoakarmament.com/ White Oak Armament's website.

 

[LKirchoff68]

thanks for the advice, keep it coming!!

links to these suppliers would be most helpful.

as for barrel length, i'm not stuck on 18" per se. i just want this upper to look drastically different from my M4gery. i'd definitely be fine with 20" or longer barrel. if the cartridge was designed for the 16" bbl then i guess that's what i'll get.

also, my most important question:

will i have any problems (cycling issues) using my carbine gas system .223 upper and a 6.8 upper with the midlength gas system on the same lower?

I didn't have any problems whatsoever when I swapped my RRA 5.56 upper for my 6.8 upper. In fact, with the factory set up that came with my complete 5.56 carbine, the rifle seemed to function better with the middy 6.8. Every spent casing ejected between 3 and 4 o'clock, and I did not experience one cycling issue from the beginning.