Weird issue with my new Stag 6.8 upper and ammo

[krevo81]

So I recently picked up a NIB Stag Hunter 20" 6.8 upper with Hogue free float HG. See specs below:

Chamber: 6.8 SPC with a SAAMI SPEC 2 chamber
Twist Rate: 1/11 button rifled
Muzzle Device: 11 degree target crown
Barrel: 20.77", 410 stainless steel, heavy profile, proprietary S7 finish to eliminate glare

Since I've been waiting on the upper, I also grabbed a few boxes of 6.8. One being the Hornady 110gr VMAX and the other being SSA's 110gr Nosler Accubond (white tip)

So I'm at the range, just having mounted the M223 mount and Nikon Buckmaster scope. Sitting at 50 yards. First shot with Hornady is on paper and bullseye height but left 3 inches. Bring it in a few shots until I put together a respectable group together in the 10 ring.

So I grab the SSA and put three rounds in the mag. I fire at a fresh target and almost don't see round hit paper. I put the gun down and walk to the target and that's when I see a new hole about a foot right and a foot high of the center of a 20" x 20" target. No way I pulled it, as the gun is in a sled.

Go back to the rifle and take a second shot, and the same thing. Only this shot is even further right and high. About 3 inches apart from the first. Take 3rd shot, and I've got a 3" grouping a foot high and right away from center of target.

I put a Hornady round back in the mag, and hit a bull cleanly. Put a SSA in, and I'm high and right and completely loose of the other 3 rounds.

What the hell? I read about both boxes of this ammo to try and find if the type of bullet is the problem. It was just really weird to me. Any ideas?

[evoutfitters]

SSA typically loads their ammo hotter than Hornady does, so I am not surprised to see you hit high. The last time I checked SSA also manufactures their own brass, so that's different as well. Shifting to the right may just be how the Accubond bullet interacts with your barrel's rifling.

[krevo81]

Well, for what it's worth, the specs on these two types of ammo were very similar outside of being a different bullet. The SSA was 50fps faster.

[krevo81]

SSA typically loads their ammo hotter than Hornady does, so I am not surprised to see you hit high. The last time I checked SSA also manufactures their own brass, so that's different as well. Shifting to the right may just be how the Accubond bullet interacts with your barrel's rifling.

Also - I was under the impression that a couple inches high and right wasn't abnormal with different brands of ammo and bullets, but a foot to 16" high and right, all while patterning sporadically at like 3-4" groups was kind of strange.

[Dr Dues]

check your scope and mount. It's not the ammo.

[krevo81]

check your scope and mount. It's not the ammo.

How would swapping between the two yield a 10 ring hit with the Hornady and a 1ft high/right shot with the SSA?

In other words, I could replicate the bullseye hit with the Hornady.

[kittyhawk]

Like Dr D said check the scope and mount. I had the same issues a while back. I found that my mountings screws were loose. I torqued them with some loc-tite and all fixed.

[BullittBoy]

My 6.8 in 1/11 twist is way more "consistent" than my older 1/10 barrel. It would shoot stuff off 4-6" from zero with different bullets but yours being off that far sounds like something is off.
My CMMG is zeroed with 110 Hornady BTHP and the 110 Accubonds are only about 3/4" to the left, but perfect elevation. I use the Hornady as my general purpose round and the Accubond as my hunting load.
Get a box of the BTHP Hornady's and maybe a box of Silver State 110 Soft Points and see how some more loads group. If they continue to be that far off from zero something is wrong

[StingerDan]

I agree it is probably a scope thing. My 6.8 Noveske shoots those 2 bullets you have listed, at appox. 1 1/2" different POI with the SSA being higher also. Probably the scope settling into the rails. I,d just retighten and try again. YMMV. Dan.

[Agnostic]

I agree it is probably a scope thing. My 6.8 Noveske shoots those 2 bullets you have listed, at appox. 1 1/2" different POI with the SSA being higher also. Probably the scope settling into the rails. I,d just retighten and try again. YMMV. Dan.

I had a similar issue. Not ever having used a quick release mount, I attached it with too little torque. Lesson learned.