I've been shooting 6.8SPC for over a year now. This SBR is the culmination of my experience to date:
Magpul M93B stock (standard H buffer)
CMT/Stag 6.8SPC marked lower
Magpul MIAD grip
CMT forged upper, extended feed ramps
CMT bolt carrier group
PRI Gas Buster charging handle (in anticipation of sound suppressor)
Noveske 12.5" 416SS heavy barrel, pinned carbine length gas block
Larue Tactical 9.0 handguard
GG&G MAD rear BUIS
Troy front BUIS
Larue Tactical SPR-EER scope mount
IOR 1.1-4x26 CRT illuminated scope
QD TangoDown shorty VFG
Surefire MB68AR brake (new to this configuration)
I've shot close to 1500 rounds through this rifle to date, including 1000 rounds during a Defensive Edge 2-day carbine class. Most of the ammo has been Hornady 110gr OTM factory loads, with some V-Max and some handloads.
Overall, the rifle has functioned quite well. I've had a handful of FTF because the Hornady 6.8 loads have an odd tendency to induce short stroking in some 6.8SPC uppers. This problem goes away when I run the bolt carrier group with a liberal coating of Slip2000 (great product, by the way). I have had no other problems to date. Some of my mags are harder to seat on to a closed bolt when full, but I'll wait to see if that goes away with more rounds downrange.
My handloads have worked quite well so far and cycle the action with much more authority than the Hornady factory loads. I have settled on 28.7gr H322 powder behind a Hornady 115gr BTHP/WC, SSA brass, and CCI #400 small rifle primers. I am consistently getting 2475-2500fps with this load with no pressure signs, which is about where I'd want a 12.5" barrel to be. These bullets will typically fragment out to 150 yards or so, which is much better than pretty much any 5.56 SBR.
Typical accuracy with the Hornady factory loads is 1-1.5MOA, and a little under 1MOA with my handloads.
I shoot this carbine out to a max of about 300 yards. Past that, I pull out my LR-308. With a 50yd zero the drop at 300 yards is about 19 inches, or 6MOA. That's right between the first and second elevation hash marks on the CQB reticle:
I have holdovers plotted out to 600 yards, but those are for extreme emergencies only...
Holding off for wind is done using the horseshoe, which is 10MOA on the inside and 18MOA on the outside at 100yds. Incidentally, the IOR is a second focal plane design, so the holds only work at 4x. This isn't a big deal, since inside 30 yards I use 1.1x and just center up the horseshoe, then crank up to 4x for anything past 30 yards.
As noted above, the Surefire brake is new, replacing an extended AR-10 type A2 flash hider. Sully had an SLR15 Grail at the class I took, and its Surefire brake did a nice job keeping muzzle flip down. I plan to get a Surefire MB68AR suppressor for this carbine, so the brake you see was the one I needed to install. Since 6.8SPC recoils noticeably more than 5.56, I'm hoping the brake will allow for faster follow-on shots (e.g. double taps, hammers, non standard response, etc). Of course, the suppressor itself (when it gets here) will make a nice muzzle brake as well, but with much less noise and pressure.
If Tim over at Ko-tonics ever decided to do a chrome lined 12.5" barrel, I would try that one in a heartbeat when replacing the Noveske (once it is shot out). It would be pretty awesome to push a 115gr projectile out of a 12.5" barrel at 2600fps.
SBRs and 6.8SPC were made for each other (literally). If you don't mind handloading (or paying $14.50/20 rounds new), 6.8SPC is great fun.
I will update once the Surefire suppressor arrives.
Magpul M93B stock (standard H buffer)
CMT/Stag 6.8SPC marked lower
Magpul MIAD grip
CMT forged upper, extended feed ramps
CMT bolt carrier group
PRI Gas Buster charging handle (in anticipation of sound suppressor)
Noveske 12.5" 416SS heavy barrel, pinned carbine length gas block
Larue Tactical 9.0 handguard
GG&G MAD rear BUIS
Troy front BUIS
Larue Tactical SPR-EER scope mount
IOR 1.1-4x26 CRT illuminated scope
QD TangoDown shorty VFG
Surefire MB68AR brake (new to this configuration)
I've shot close to 1500 rounds through this rifle to date, including 1000 rounds during a Defensive Edge 2-day carbine class. Most of the ammo has been Hornady 110gr OTM factory loads, with some V-Max and some handloads.
Overall, the rifle has functioned quite well. I've had a handful of FTF because the Hornady 6.8 loads have an odd tendency to induce short stroking in some 6.8SPC uppers. This problem goes away when I run the bolt carrier group with a liberal coating of Slip2000 (great product, by the way). I have had no other problems to date. Some of my mags are harder to seat on to a closed bolt when full, but I'll wait to see if that goes away with more rounds downrange.
My handloads have worked quite well so far and cycle the action with much more authority than the Hornady factory loads. I have settled on 28.7gr H322 powder behind a Hornady 115gr BTHP/WC, SSA brass, and CCI #400 small rifle primers. I am consistently getting 2475-2500fps with this load with no pressure signs, which is about where I'd want a 12.5" barrel to be. These bullets will typically fragment out to 150 yards or so, which is much better than pretty much any 5.56 SBR.
Typical accuracy with the Hornady factory loads is 1-1.5MOA, and a little under 1MOA with my handloads.
I shoot this carbine out to a max of about 300 yards. Past that, I pull out my LR-308. With a 50yd zero the drop at 300 yards is about 19 inches, or 6MOA. That's right between the first and second elevation hash marks on the CQB reticle:
I have holdovers plotted out to 600 yards, but those are for extreme emergencies only...
Holding off for wind is done using the horseshoe, which is 10MOA on the inside and 18MOA on the outside at 100yds. Incidentally, the IOR is a second focal plane design, so the holds only work at 4x. This isn't a big deal, since inside 30 yards I use 1.1x and just center up the horseshoe, then crank up to 4x for anything past 30 yards.
As noted above, the Surefire brake is new, replacing an extended AR-10 type A2 flash hider. Sully had an SLR15 Grail at the class I took, and its Surefire brake did a nice job keeping muzzle flip down. I plan to get a Surefire MB68AR suppressor for this carbine, so the brake you see was the one I needed to install. Since 6.8SPC recoils noticeably more than 5.56, I'm hoping the brake will allow for faster follow-on shots (e.g. double taps, hammers, non standard response, etc). Of course, the suppressor itself (when it gets here) will make a nice muzzle brake as well, but with much less noise and pressure.
If Tim over at Ko-tonics ever decided to do a chrome lined 12.5" barrel, I would try that one in a heartbeat when replacing the Noveske (once it is shot out). It would be pretty awesome to push a 115gr projectile out of a 12.5" barrel at 2600fps.
SBRs and 6.8SPC were made for each other (literally). If you don't mind handloading (or paying $14.50/20 rounds new), 6.8SPC is great fun.
I will update once the Surefire suppressor arrives.
