LVLAaron
Gold $$ Contributor
Built a new AR10.
* Aero Precision Receiver
* Toolcraft Bolt/BCG
* Elf trigger
* Ballistic Advantage 18" .308 Heavy Rifle barrel (1:10 twist)
* VG6 Gamma brake
* SWFA 10x SS Scope
I've doubled checked that everything is tight and nothing is loose. I know the scope is good, I took it off a .223 I'd shoot bugholes all day with.
The first rounds through the gun were 20 Hornady Black 168's
Sticking with Hornady 308 brass and CCI-BR2 primers.
Next I tested a bunch of other Hornady 168 BTHP's and wasn't in love. Ran out of those, picked up some sierra match king 168's and that brings us to today.
12 groups in .3 grain increments of IMR 4166
Rough load data from Quickload:
Chrono (labradar) data from the trip
I'm struggling to keep 2 inch groups @ 100 yards. I'm tired from the holiday and a little frustrated, so I could use some help from the hive mind.
* Aero Precision Receiver
* Toolcraft Bolt/BCG
* Elf trigger
* Ballistic Advantage 18" .308 Heavy Rifle barrel (1:10 twist)
* VG6 Gamma brake
* SWFA 10x SS Scope
I've doubled checked that everything is tight and nothing is loose. I know the scope is good, I took it off a .223 I'd shoot bugholes all day with.

The first rounds through the gun were 20 Hornady Black 168's
Sticking with Hornady 308 brass and CCI-BR2 primers.
Next I tested a bunch of other Hornady 168 BTHP's and wasn't in love. Ran out of those, picked up some sierra match king 168's and that brings us to today.
12 groups in .3 grain increments of IMR 4166
Rough load data from Quickload:
Code:
Cartridge : .308 Win. (SAAMI)
Bullet : .308, 168, Sierra HPBT MatchK 2200 G7Litz
Useable Case Capaci: 48.726 grain H2O = 3.164 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length : 18.0 inch = 457.2 mm
Powder : IMR 4166 Enduron
Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.671% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !
Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms
-06.7 97 41.70 2332 2029 46606 9268 89.8 1.078
-06.0 98 42.00 2349 2059 47579 9349 90.1 1.067
-05.4 98 42.30 2366 2089 48572 9429 90.5 1.057
-04.7 99 42.60 2383 2119 49587 9509 90.8 1.046
-04.0 100 42.90 2400 2149 50623 9588 91.1 1.036
-03.4 100 43.20 2418 2180 51682 9666 91.4 1.026
-02.7 101 43.50 2435 2211 52764 9743 91.8 1.016 ! Near Maximum !
-02.0 102 43.80 2452 2242 53869 9819 92.1 1.007 ! Near Maximum !
-01.3 103 44.10 2469 2274 54999 9895 92.4 0.997 ! Near Maximum !
-00.7 103 44.40 2486 2305 56154 9969 92.7 0.988 ! Near Maximum !
+00.0 104 44.70 2503 2337 57334 10043 93.0 0.978 ! Near Maximum !
+00.7 105 45.00 2520 2369 58540 10116 93.3 0.969 ! Near Maximum !
+01.3 105 45.30 2537 2402 59774 10188 93.6 0.960 ! Near Maximum !
+02.0 106 45.60 2554 2434 61035 10259 93.8 0.951 ! Near Maximum !
+02.7 107 45.90 2572 2467 62324 10329 94.1 0.941 !DANGEROUS LOAD-DO NOT USE!
+03.4 107 46.20 2589 2500 63644 10397 94.4 0.933 !DANGEROUS LOAD-DO NOT USE!
Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 104 44.70 2627 2575 66762 10297 97.8 0.913 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 104 44.70 2350 2061 48186 9439 85.6 1.061
Chrono (labradar) data from the trip
Code:
4166 / Grains
Stats - Average 2405.55 Group 1 - 41.4
Stats - Highest 2450.22
Stats - Lowest 2367.33
Stats - Ext. Spread 82.89
Stats - Std. Dev 31.78
Stats - Average 2419.86 Group 2 - 41.7
Stats - Highest 2433.56
Stats - Lowest 2406.06
Stats - Ext. Spread 27.5
Stats - Std. Dev 11.85
Stats - Average 2428.67 Group 3 - 42
Stats - Highest 2449.49
Stats - Lowest 2374.84
Stats - Ext. Spread 74.65
Stats - Std. Dev 31.47
Stats - Average 2437.98 Group 4 - 42.3
Stats - Highest 2471.77
Stats - Lowest 2408.07
Stats - Ext. Spread 63.7
Stats - Std. Dev 25.8
Stats - Average 2462.62 Group 5 - 42.6
Stats - Highest 2474.12
Stats - Lowest 2442.51
Stats - Ext. Spread 31.61
Stats - Std. Dev 12.17
Stats - Average 2481.8 Group 6 - 42.9
Stats - Highest 2512.48
Stats - Lowest 2452.42
Stats - Ext. Spread 60.06
Stats - Std. Dev 21.61
Stats - Average 2509.11 Group 7 - 43.2
Stats - Highest 2518.03
Stats - Lowest 2501.35
Stats - Ext. Spread 16.69
Stats - Std. Dev 6.71
Stats - Average 2508.6 Group 8 - 43.5
Stats - Highest 2519.9
Stats - Lowest 2487.17
Stats - Ext. Spread 32.73
Stats - Std. Dev 15.22
Stats - Average 2518.48 Group 9 - 43.8
Stats - Highest 2548.3
Stats - Lowest 2491.72
Stats - Ext. Spread 56.58
Stats - Std. Dev 23.17
Stats - Average 2546.29 Group 10 - 44.1
Stats - Highest 2573.08
Stats - Lowest 2518.43
Stats - Ext. Spread 54.65
Stats - Std. Dev 20.93
Stats - Average 2376.08 Group 11 - 44.4
Stats - Highest 2391.89
Stats - Lowest 2365.77
Stats - Ext. Spread 26.12
Stats - Std. Dev 10.58
Stats - Average 2403.9 Group 12 - 44.7
Stats - Highest 2422.26
Stats - Lowest 2382.89
Stats - Ext. Spread 39.38
Stats - Std. Dev 16.87
I'm struggling to keep 2 inch groups @ 100 yards. I'm tired from the holiday and a little frustrated, so I could use some help from the hive mind.