Cooler Temp 6.8mm SPC experiments, STAG AR getting better..

[Float Pilot]

6.8 x 43mm Remington SPC Page two

It was not as cold as the other day, but I managed to get in a few shots.

Conditions:
Rifle: Stag 16 inch flat-top, 1 in 10 twist SPCII chamber, A2 buttstock with Tubbs flat spring
Sights: fixed 6 power Leupold.
Range 100 yards
Temp: 32 degrees F , 0 C
Light: Flat fading light on snow.

LOADS:
A:
Bullet: 100 grain Sierra sp, flat base
Powder: 30.0 grains, H-322
Primer: Remington 7 1/2 bench rest small rifle, hand seated
Brass: SSA
COL: 2.240 inch Lee Factory Crimp
Velocity average: 2,576 fps 40 fps ES
1.50 inch group with last shot flyer to 2.5 inch. No pressure signs

B:
Bullet: 100 grain Sierra sp. flat base
Powder: 30.0 grains, H-322
Primer: CCI-400 small rifle, hand seated
Brass: SSA
COL: 2.240 inch med roll crimp.
Velocity average: 2,556 fps 9 fps ES
0.35 inch group with last shot flyer to 0.80 inch. Flat Primers
ACCURATE LOAD just from changing the PRIMER


C:
Bullet: 110 grain Hornady Flat Base, Hollow Point
Powder: 29.0 grains,H-322.
Primer: CCI-400 small rifle, hand seated
Brass: SSA
COL: 2.260 inch. Lee Factory Crimp
Velocity average: 2,500 fps 60 fps ES
3.75 inch group, Flat Primers NOT A GOOD LOAD

D:
Bullet: 110 grain Nosler Accubond Boat-Tail
Powder: 29.0 grains H-322
Primer: CCI-400 Small Rifle hand seated
Brass: SSA
COL: 2.260 inch Lee Factory Crimp
Velocity average: 2,500 fps 15 fps ES
1.0 inch group,,,, with last shot flyer to 1.5 Flat Primers
GOOD ALL AROUND LOAD


E:
Bullet: 110 grain Hornady V-MAX factory load
Powder: Factory
Primer: Factory large
Brass: Hornady
COL:
Velocity average: 2,446 fps 75 fps ES
2.7 inch group No pressure signs This factory ammo stinks

 

[R.W.Dale]

Looks like those CCI primers are the way to go. All my accuracy loads for my bench gun employ either a CCI400 or a BR4 primer.

Is 29.2grs of H322 a max load?

 

[HorseSoldier]

Quite impressive tightening on group size just from the primer switch.