Disappointing Range Day 270 WIN -

DrMike":1foy9miy said:
I witnessed and verified changes of accuracy going from >MOA to 0.1MOA with 0.005 inches of change. Obviously, with that sort of sensitivity, it would be impossible to use. I notified the customer in that particular instance, but strongly recommended that we keep looking for a load that would be easier for him to duplicate. It was surely dramatic, and it was reproducible. Again, I've witnessed some pretty dramatic changes in "go to" loads for my own rifles when changing lots of bullets. For that reason, I am compelled to verify each time I change lots of the several components.

Good to know, I'll make sure to check them after each change! I had no idea.
 
Todd, here is some data to look at..

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 90, Nosler Bonded Perf 38140
Useable Case Capaci: 65.086 grain H2O = 4.226 cm³
Cartridge O.A.L. L6: 3.200 inch = 81.28 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 4007 SSC

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 79 48.00 2761 1523 31605 9277 82.1 1.230
-18.0 81 49.20 2832 1602 33753 9606 83.6 1.198
-16.0 83 50.40 2903 1684 36044 9931 85.1 1.166
-14.0 85 51.60 2975 1769 38489 10250 86.5 1.132
-12.0 87 52.80 3047 1855 41099 10562 87.8 1.096
-10.0 89 54.00 3119 1944 43885 10868 89.1 1.062
-08.0 91 55.20 3192 2036 46862 11164 90.3 1.029
-06.0 93 56.40 3264 2130 50043 11451 91.5 0.998
-04.0 95 57.60 3337 2226 53445 11726 92.6 0.967
-02.0 97 58.80 3410 2324 57086 11990 93.6 0.938 ! Near Maximum !
+00.0 99 60.00 3483 2425 60987 12240 94.6 0.910 ! Near Maximum !
+02.0 101 61.20 3557 2528 65170 12475 95.5 0.882 !DANGEROUS LOAD-DO NOT USE!
+04.0 103 62.40 3630 2633 69660 12695 96.3 0.856 !DANGEROUS LOAD-DO NOT USE!
+06.0 105 63.60 3703 2741 74487 12898 97.1 0.830 !DANGEROUS LOAD-DO NOT USE!
+08.0 106 64.80 3777 2850 79682 13082 97.7 0.806 !DANGEROUS LOAD-DO NOT USE!
+10.0 108 66.00 3850 2962 85282 13247 98.3 0.782 !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 99 60.00 3662 2679 71631 12464 98.8 0.843 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 99 60.00 3260 2124 50602 11534 87.3 0.995


Cartridge : .270 Win. (SAAMI)
Bullet : .277, 90, Nosler Bonded Perf 38140
Useable Case Capaci: 65.086 grain H2O = 4.226 cm³
Cartridge O.A.L. L6: 3.200 inch = 81.28 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 3031

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 77 43.20 2933 1720 33207 10129 97.5 1.191
-18.0 79 44.28 3000 1799 35422 10362 98.3 1.161
-16.0 81 45.36 3067 1879 37760 10575 98.9 1.129
-14.0 83 46.44 3132 1961 40234 10768 99.4 1.096
-12.0 85 47.52 3197 2043 42854 10940 99.7 1.065
-10.0 87 48.60 3262 2126 45625 11089 99.9 1.034
-08.0 89 49.68 3325 2209 48558 11215 100.0 1.005
-06.0 91 50.76 3387 2293 51661 11325 100.0 0.977
-04.0 92 51.84 3449 2377 54944 11433 100.0 0.950
-02.0 94 52.92 3509 2461 58417 11538 100.0 0.924 ! Near Maximum !
+00.0 96 54.00 3569 2545 62094 11640 100.0 0.899 ! Near Maximum !
+02.0 98 55.08 3628 2630 65985 11740 100.0 0.875 !DANGEROUS LOAD-DO NOT USE!
+04.0 100 56.16 3686 2715 70107 11836 100.0 0.852 !DANGEROUS LOAD-DO NOT USE!
+06.0 102 57.24 3744 2801 74474 11929 100.0 0.830 !DANGEROUS LOAD-DO NOT USE!
+08.0 104 58.32 3801 2887 79102 12020 100.0 0.808 !DANGEROUS LOAD-DO NOT USE!
+10.0 106 59.40 3858 2974 84012 12106 100.0 0.788 !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 96 54.00 3682 2709 73632 11270 100.0 0.836 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 96 54.00 3396 2305 50501 12081 99.4 0.984


You have GOTTA run one of them in the jugs around 3500 though! They are some tough bullets and that would be a GREAT test...
 
SJB358":2ry0m4ni said:
Todd, here is some data to look at..

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 90, Nosler Bonded Perf 38140
Useable Case Capaci: 65.086 grain H2O = 4.226 cm³
Cartridge O.A.L. L6: 3.200 inch = 81.28 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 4007 SSC

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 79 48.00 2761 1523 31605 9277 82.1 1.230
-18.0 81 49.20 2832 1602 33753 9606 83.6 1.198
-16.0 83 50.40 2903 1684 36044 9931 85.1 1.166
-14.0 85 51.60 2975 1769 38489 10250 86.5 1.132
-12.0 87 52.80 3047 1855 41099 10562 87.8 1.096
-10.0 89 54.00 3119 1944 43885 10868 89.1 1.062
-08.0 91 55.20 3192 2036 46862 11164 90.3 1.029
-06.0 93 56.40 3264 2130 50043 11451 91.5 0.998
-04.0 95 57.60 3337 2226 53445 11726 92.6 0.967
-02.0 97 58.80 3410 2324 57086 11990 93.6 0.938 ! Near Maximum !
+00.0 99 60.00 3483 2425 60987 12240 94.6 0.910 ! Near Maximum !
+02.0 101 61.20 3557 2528 65170 12475 95.5 0.882 !DANGEROUS LOAD-DO NOT USE!
+04.0 103 62.40 3630 2633 69660 12695 96.3 0.856 !DANGEROUS LOAD-DO NOT USE!
+06.0 105 63.60 3703 2741 74487 12898 97.1 0.830 !DANGEROUS LOAD-DO NOT USE!
+08.0 106 64.80 3777 2850 79682 13082 97.7 0.806 !DANGEROUS LOAD-DO NOT USE!
+10.0 108 66.00 3850 2962 85282 13247 98.3 0.782 !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 99 60.00 3662 2679 71631 12464 98.8 0.843 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 99 60.00 3260 2124 50602 11534 87.3 0.995


Cartridge : .270 Win. (SAAMI)
Bullet : .277, 90, Nosler Bonded Perf 38140
Useable Case Capaci: 65.086 grain H2O = 4.226 cm³
Cartridge O.A.L. L6: 3.200 inch = 81.28 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 3031

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 77 43.20 2933 1720 33207 10129 97.5 1.191
-18.0 79 44.28 3000 1799 35422 10362 98.3 1.161
-16.0 81 45.36 3067 1879 37760 10575 98.9 1.129
-14.0 83 46.44 3132 1961 40234 10768 99.4 1.096
-12.0 85 47.52 3197 2043 42854 10940 99.7 1.065
-10.0 87 48.60 3262 2126 45625 11089 99.9 1.034
-08.0 89 49.68 3325 2209 48558 11215 100.0 1.005
-06.0 91 50.76 3387 2293 51661 11325 100.0 0.977
-04.0 92 51.84 3449 2377 54944 11433 100.0 0.950
-02.0 94 52.92 3509 2461 58417 11538 100.0 0.924 ! Near Maximum !
+00.0 96 54.00 3569 2545 62094 11640 100.0 0.899 ! Near Maximum !
+02.0 98 55.08 3628 2630 65985 11740 100.0 0.875 !DANGEROUS LOAD-DO NOT USE!
+04.0 100 56.16 3686 2715 70107 11836 100.0 0.852 !DANGEROUS LOAD-DO NOT USE!
+06.0 102 57.24 3744 2801 74474 11929 100.0 0.830 !DANGEROUS LOAD-DO NOT USE!
+08.0 104 58.32 3801 2887 79102 12020 100.0 0.808 !DANGEROUS LOAD-DO NOT USE!
+10.0 106 59.40 3858 2974 84012 12106 100.0 0.788 !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 96 54.00 3682 2709 73632 11270 100.0 0.836 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 96 54.00 3396 2305 50501 12081 99.4 0.984


You have GOTTA run one of them in the jugs around 3500 though! They are some tough bullets and that would be a GREAT test...

Thanks Scotty! I will as soon as it stops raining!
 
One of my best loads from my 270 Win (22" barrel) was with 56gn of IMR 4831 and 130gn Ballistic Tips. A slower, but more accurate load was 49gn of H-414 with the same bullet.
 
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