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Given: Ruger M77 MkII, 30-06, sporter weight barrel
Equipment: Forster Co-Ax press, Forster benchrest dies
Components: 180 Rem Accu-tip, Rem once fired brass (weight sorted), AA4350, Fed 210
Preparation: Brass annealed prior to resizing
Length to lands 3.365"
Max mag length 3.365"
Full caliber seating depth 3.325"
Method:
A) 2 rnds fired of each charge (charge weights accurate to 2 kernals of powder) to find max charge via Magnetospeed,
B) 2 rnds of each charge fired in the manner of an OCW at 100 yards (experimental, regular OCW is 3 rounds per charge),
C) seating depth test in .005" increments.
Pressure Test:
57 grains - 2612, 2605 Avg. 2608 Base expansion .4680"
57.5 grains - 2635, 2653 Avg. 2644 Base expansion .4685"
58 grains - 2685, 2691 Avg. 2688 Base expansion .4685"
58.5 grains - 2695, 2693 Avg. 2694 Base expansion .4688"
59 grains - Not tested, no more room in case, grains started crunching.
Notes on pressure Test: Temperature 50*F, 58.5 grains was full pressure but not hot. 59 grains if able to test, most likely would have seen pressure. Velocity seemed more consistent beginning at 58 grains. Powder burn was clean with all loads, full base expansion happened at 57.5 grains.
Theory: Guessing that pressure would have been seen at 59 grains. I would expect a node to show up at around 2% backed off from pressure, I would expect the node to show up around 57.8 grains.
Modified OCW test, 2 rounds per charge. 1 round fired on wrong target and annotated. Lines drawn from center to center of each pair and from that center to POA.
Notes: Sporter weight barrel exhibits same up and down pattern, albeit much more dramatically. It seems that the group size has a large variation also. This would make sense given the thin barrel. There seems to be a relative flat spot between 58 grains and 58.2 grains. The height is similar and the direction from POA is the most consistent of the charges presented.
My prediction was 57.8 grains (59 grains x .98), the chosen charge was 58.1 grains.
Seating Depth Test 100 yards:
OAL 3.325"
OAL 3.330"
OAL 3.335"
OAL 3.340"
Notes: The seating depth test was as dramatic as the OCW. Group sizes were from over 3moa to just over 1moa with a .005" change in seating depth.
Equipment: Forster Co-Ax press, Forster benchrest dies
Components: 180 Rem Accu-tip, Rem once fired brass (weight sorted), AA4350, Fed 210
Preparation: Brass annealed prior to resizing
Length to lands 3.365"
Max mag length 3.365"
Full caliber seating depth 3.325"
Method:
A) 2 rnds fired of each charge (charge weights accurate to 2 kernals of powder) to find max charge via Magnetospeed,
B) 2 rnds of each charge fired in the manner of an OCW at 100 yards (experimental, regular OCW is 3 rounds per charge),
C) seating depth test in .005" increments.
Pressure Test:
57 grains - 2612, 2605 Avg. 2608 Base expansion .4680"
57.5 grains - 2635, 2653 Avg. 2644 Base expansion .4685"
58 grains - 2685, 2691 Avg. 2688 Base expansion .4685"
58.5 grains - 2695, 2693 Avg. 2694 Base expansion .4688"
59 grains - Not tested, no more room in case, grains started crunching.
Notes on pressure Test: Temperature 50*F, 58.5 grains was full pressure but not hot. 59 grains if able to test, most likely would have seen pressure. Velocity seemed more consistent beginning at 58 grains. Powder burn was clean with all loads, full base expansion happened at 57.5 grains.
Theory: Guessing that pressure would have been seen at 59 grains. I would expect a node to show up at around 2% backed off from pressure, I would expect the node to show up around 57.8 grains.
Modified OCW test, 2 rounds per charge. 1 round fired on wrong target and annotated. Lines drawn from center to center of each pair and from that center to POA.
Notes: Sporter weight barrel exhibits same up and down pattern, albeit much more dramatically. It seems that the group size has a large variation also. This would make sense given the thin barrel. There seems to be a relative flat spot between 58 grains and 58.2 grains. The height is similar and the direction from POA is the most consistent of the charges presented.
My prediction was 57.8 grains (59 grains x .98), the chosen charge was 58.1 grains.
Seating Depth Test 100 yards:
OAL 3.325"
OAL 3.330"
OAL 3.335"
OAL 3.340"
Notes: The seating depth test was as dramatic as the OCW. Group sizes were from over 3moa to just over 1moa with a .005" change in seating depth.
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