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Accurate AA2200 Powder Performance in .223
Following was shot with an
AR-15 upper built by Frank White of Compass Lake Engineering, and is a
flattop upper with a 26" Krieger heavy stainless steel barrel. A Tasco
World Class Plus 8-32x44mm target scope was used on the highest
magnification. The lower was assembled by the author and includes AR-15A2
furniture and a Jewell 2-stage trigger with both stages set as light as
functioning allowed. The bore has been moly coated according to the
procedure documented elsewhere on this website. The bullets were all moly
plated according to the procedure documented elsewhere on this website.
The groups were shot
from benchrest free-recoil using a Bald Eagle front rest and rear
rabbit-earred bag.
Legend
All group measurements are in inches.
Diameter: diameter of the smallest circle centered on the
centroid of the group that encompasses all the rounds. A
perfectly symetrical group will have equal diameter and measured
sizes, otherwise the diameter will always be larger than the
measured size.
H-Spread: Horizontal extreme spread
V-Spread: Vertical extreem spread
Measured: value is the largest distance between the centers
of any 2 bullet holes. This is how groups are typically measured.
MV Spread: extreme spread of muzzle velocity for the group in FPS
Centroid H/V: Horizontal and vertical centroids (averages) of the group.
This represents the center (of gravity) of the group.
Mean2: value is calculated by tossing the maximum value on the
row and recalculating. This is an attempt to get a measure of shooter
independence, that is, I assume that the worst performance is a result
of poor shooter performance.
Overall: values are calculated across all 25 rounds treated as
a single group.
Last 2 columns are the Muzzle Velocity data in FPS.
Each load summary table is followed by 6 target plots, one for each group,
and a sixth for the 25 round overall group size. Each target plot is a
2" x 2" square, with the rounds plotted as circles and the centroid of the
group plotted as a square. Not much care was given to zeroing the scope,
hence the wandering centroids. This was shorting for group not accuracy.
22.5 grains AA2200
| Group |
1 |
2 |
3 |
4 |
5 |
Mean |
Mean2 |
Overall |
Mean: |
3050.8 |
| Diameter |
0.526 |
0.586 |
0.595 |
0.978 |
0.741 |
0.685 |
0.612 |
NA |
Min: |
2999.0 |
| H-Spread |
0.394 |
0.236 |
0.453 |
0.472 |
0.354 |
0.382 |
0.359 |
0.630 |
Max: |
3125.0 |
| V-Spread |
0.315 |
0.531 |
0.354 |
0.728 |
0.610 |
0.508 |
0.453 |
0.886 |
Spread |
126.0 |
| Measured |
0.470 |
0.582 |
0.463 |
0.835 |
0.612 |
0.592 |
0.532 |
0.951 |
StdDev: |
30.4 |
23.0 grains AA2200
| Group |
1 |
2 |
3 |
4 |
5 |
Mean |
Mean2 |
Overall |
Mean: |
3113.1 |
| Diameter |
1.150 |
0.698 |
0.869 |
0.628 |
0.602 |
0.789 |
0.699 |
NA |
Min: |
3059.0 |
| H-Spread |
0.827 |
0.650 |
0.768 |
0.571 |
0.531 |
0.669 |
0.630 |
1.024 |
Max: |
3227.0 |
| V-Spread |
1.074 |
0.650 |
0.846 |
0.572 |
0.567 |
0.742 |
0.659 |
0.925 |
Spread |
168.0 |
| Measured |
1.074 |
0.650 |
0.846 |
0.572 |
0.567 |
0.742 |
0.659 |
1.076 |
StdDev: |
49.2 |
23.5 grains AA2200
| Group |
1 |
2 |
3 |
4 |
5 |
Mean |
Mean2 |
Overall |
Mean: |
3251.6 |
| Diameter |
0.976 |
0.891 |
0.793 |
0.977 |
0.701 |
0.868 |
0.840 |
NA |
Min: |
3157.0 |
| H-Spread |
0.591 |
0.571 |
0.335 |
0.669 |
0.650 |
0.563 |
0.536 |
0.945 |
Max: |
3335.0 |
| V-Spread |
0.768 |
0.531 |
0.551 |
0.394 |
0.394 |
0.528 |
0.468 |
0.925 |
Spread |
178.0 |
| Measured |
0.780 |
0.780 |
0.608 |
0.717 |
0.664 |
0.710 |
0.692 |
1.067 |
StdDev: |
54.5 |
24.0 grains AA2200
| Group |
1 |
2 |
3 |
4 |
5 |
Mean |
Mean2 |
Overall |
Mean: |
3284.6 |
| Diameter |
0.671 |
0.511 |
0.828 |
0.870 |
0.945 |
0.765 |
0.720 |
NA |
Min: |
3200.0 |
| H-Spread |
0.492 |
0.413 |
0.650 |
0.531 |
0.394 |
0.496 |
0.458 |
0.748 |
Max: |
3344.0 |
| V-Spread |
0.354 |
0.295 |
0.394 |
0.571 |
0.748 |
0.472 |
0.404 |
0.807 |
Spread |
144.0 |
| Measured |
0.606 |
0.450 |
0.685 |
0.673 |
0.757 |
0.634 |
0.604 |
0.831 |
StdDev: |
33.6 |
24.5 grains AA2200
| Group |
1 |
2 |
3 |
4 |
5 |
Mean |
Mean2 |
Overall |
Mean: |
3252.3 |
| Diameter |
0.531 |
0.432 |
0.835 |
0.815 |
0.693 |
0.661 |
0.618 |
NA |
Min: |
3198.0 |
| H-Spread |
0.118 |
0.335 |
0.591 |
0.551 |
0.492 |
0.417 |
0.374 |
0.886 |
Max: |
3286.0 |
| V-Spread |
0.492 |
0.276 |
0.610 |
0.512 |
0.295 |
0.437 |
0.394 |
0.846 |
Spread |
88.0 |
| Measured |
0.506 |
0.419 |
0.698 |
0.713 |
0.503 |
0.568 |
0.531 |
1.100 |
StdDev: |
24.1 |
25.0 grains AA2200
| Group |
1 |
2 |
3 |
4 |
5 |
Mean |
Mean2 |
Overall |
Mean: |
3522.8 |
| Diameter |
0.624 |
0.588 |
0.686 |
0.458 |
0.817 |
0.635 |
0.589 |
NA |
Min: |
3448.0 |
| H-Spread |
0.472 |
0.492 |
0.591 |
0.433 |
0.374 |
0.472 |
0.443 |
0.748 |
Max: |
3566.0 |
| V-Spread |
0.531 |
0.138 |
0.217 |
0.059 |
0.610 |
0.311 |
0.236 |
0.787 |
Spread |
118.0 |
| Measured |
0.549 |
0.511 |
0.606 |
0.437 |
0.626 |
0.546 |
0.526 |
0.822 |
StdDev: |
34.0 |
