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mich1377usmc 09-29-2012 10:41 AM

Lower for 6.8 SPC
This is my first trip down this path , building an AR not shooting one. Have read & watched the stickies, VERY well done by ALL. My question is; will ANY mil-spec lower be strong enough for the 6.8 ?? Any maker better than the others are all just about the same ?? This weapon will be used as a range / SHTF / I,m the ODDBALL that shoots 6.8 firearm. Thank You in advance Mickey

Sniper03 09-30-2012 12:17 AM


Any good lower assembly will be fine for the 6.8 SPC. It is a good round I might add. Certainly a little more expensive unless you reload but is superior to the 5.56. I would suggest the following: Rock River Arms because I love the 2 Stage Trigger and RRA/Hogue grip along with the Star Selector which you can get. Others are Stag Arms, Spikes Tactical, Daniel Defense,Double Star, but any good Lower will do just fine. Let us see some Pics when you get it built.:)


nitestalker 09-30-2012 12:22 AM

What changes are needed to use the 6.8 on a standard Colt preban lower? Can this be done by just changing the upper and magazine?

TheAlmightyBob 09-30-2012 01:48 AM

Any receiver will work. And other than barrel and mag, you also need a bolt head. The case rim is slightly larger than the standard 223.

nitestalker 09-30-2012 03:43 AM

Thx for the Info.:)

mich1377usmc 09-30-2012 07:38 AM

Thank you for the imput 03. Now I can make an informed purchase from one of the LGS OR NEXT GUN SHOW, them ID 10T will try to sell you the most expensive thing in the case if you let them. Ammo is no prob as I've been reloading for going on 40 years, the first purchase will be hard to swallow but all down hill after that. Have done alot of comparing between 5.56 to 6.8 , it does look like a better round just never fired weapon chambered for ithat caliber. Qualified with M16A1's in the Corps, glad I was an 81mm FO/RTO an carried a 1911A1. Now on to optics , will stay with iron sights at first , but that is another day. Mickey

mich1377usmc 10-04-2012 10:03 AM

Been doing research . Have a question for the board , in 6.8 SPC any difference between I or II chambers ie, 6.8 SPC II ? Have from a nice upper kit from M&A. Thank You for the replies. Mickey

TheAlmightyBob 10-05-2012 07:09 AM

stolen from else where.

6.8 SPC Chambers Available:

1: SAAMI / 0.05 " throat / akin to .223 standard
2: SPC II / 0.10" throat / akin to 5.56 NATO
3: DMR / 0.08" throat & a 30 degree case to leade taper instead of 45 degrees / akin to .223 Wylde

Dimensions of the 6.8 SPC
**************new case––-resized case ––-SAAMI––––––-SPCII––-DMR
base dia. ******* .4155***** .418**** * .422***** .422 ***** .4205
shoulder dia. ***** .402 * ** .402 ***** .4028**** * .4028 **** .403
neck @ shoulder dia* .301 *** .301 **** .3085**** .3085 ***** .305
neck @ throat dia ** .301 *** .301****** .307 ***** .308 **** .304
leade dia. ***************** ********* .2781**** .2781 **** .277
length of leade ******************** ** .064**** .105 ****** .095

eta: spec1 chambers had problems with hot loads. Starts showing pressure signs early. Just thought you should know.

mich1377usmc 10-05-2012 11:12 AM

Bob Thanx for the reply That was my thinking on difference the between chambers. Going to call retailer today and get more specs. Even if this outfit is just a SAAMI chamber will still purchase because its a good deal. Can always up grade barrel at latter date. Mickey

Gatoragn 10-05-2012 11:24 AM

I have a LMT 6.8 carbine upper. I acquired a DPMS (gasp) stripped lower, RRA parts kit w/2 stage trigger. Since I assembled this exclusively for hunting I used a fixed stock. On the upper I cut down the front sight and installed a mid-length free float hand guard.

It will shoot minute of venison all day. Now I just need a couple of Bambi daddies or mommas to show up this year.

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