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Old June 1, 2011, 01:21 PM   #31
Unclenick
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Join Date: March 4, 2005
Location: Ohio
Posts: 21,063
Below is from QuickLOAD showing the maximum velocity performance ranking for a couple of different bullet weights from some commonly used powders. The criteria I gave it was to load to 100% fill (no compressing) or to 55,000 PSI, whichever was reached first. Both are seated to 2.260" COL. The barrel is 20" for the AR, but the velocity ranking from fastest to slowest doesn't change for barrels 16" and longer. The case capacity is 30.5 grains of water, which is just a typical number coming out of one of my chambers.

Note that some popular powders, like Varget, need compressed loads to match some of the others, which the table below does not allow it to do. Note also that the 55,000 psi limit is SAAMI's. The CIP in Europe allows 430MPa (62,366 psi). They measure it with their pressure sampling points differently located.

Accuracy often depends on ignition characteristics as well as case fill or pressure, so it does not automatically follow that you can discern accuracy from this kind of table. It does, however, give you some sense of how burning rate and bulk density may combine to affect rank of a powder or its potential performance. In the example below, 748 is dense so it is able to be loaded to full pressure in both cases, while, at the other extreme, Varget has more bulk, so it fills the case before reaching the pressure limit.

Code:
77 grain SMK 2.26" COL, 24" barrel
case 100% full or pressure 55,000 psi, whichever comes first.


   77 gr. SMK  53 gr. SMK      77 gr. fps         53 gr. fps

          748   748               2776               3283
      BL-C(2)   H335              2771               3248
        H4895   H322              2751               3245
          TAC   X-terminator      2737               3243
         H335   REL 10X           2735               3241
         H322   TAC               2733               3237
     IMR 4895   Accurate 2015     2727               3217
 X-terminator   IMR 4198          2722               3207
     IMR 3031   Accurate 2230     2715               3202
Accurate 2230   BL-C(2)           2701               3194
      REL 10X   H4198             2698               3162
Accurate 2015   Benchmark         2686               3162
    Benchmark   H4895             2679               3122
     IMR 4198   IMR 3031          2657               3045
        H4198   IMR 4895          2643               3033
       Varget   Varget            2600               2902
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