Quick Load data for N560 in the 308 Norma Mag?

Wenaha · Tuesday at 10:57 AM

I have these components to work with:

Brass - unfired Norma
Primer - Federal GM 215M or Rem 9-1/2M
Powder - VV N560 and H4831sc
Bullet - Swift Scirocco II 180 gr.

Thanks for any help on this.

TackDriver284 · Tuesday at 11:52 AM

I don't have your fired case dimensions for a more accurate result, this is just an estimation so please work up.

Code:

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   91    63.00   2602    2707   41284  10125     91.8    1.379
-09.0   92    63.70   2633    2770   42661  10260     92.3    1.358
-08.0   93    64.40   2663    2834   44088  10393     92.9    1.337
-07.0   94    65.10   2693    2899   45566  10524     93.4    1.316
-06.0   95    65.80   2723    2965   47097  10651     93.9    1.296
-05.0   96    66.50   2754    3031   48686  10775     94.4    1.276
-04.0   97    67.20   2784    3099   50331  10896     94.9    1.257
-03.0   98    67.90   2815    3167   52040  11014     95.3    1.238
-02.0   99    68.60   2845    3236   53811  11129     95.8    1.219
-01.0  100    69.30   2876    3306   55650  11239     96.2    1.201  ! Near Maximum !
+00.0  101    70.00   2907    3377   57537  11346     96.6    1.182  ! Near Maximum !
+01.0  102    70.70   2937    3448   59541  11449     97.0    1.164  ! Near Maximum !
+02.0  103    71.40   2968    3521   61601  11548     97.3    1.147  ! Near Maximum !
+03.0  104    72.10   2999    3594   63741  11642     97.7    1.129  !DANGEROUS LOAD-DO NOT USE!
+04.0  105    72.80   3029    3668   65967  11733     98.0    1.112  !DANGEROUS LOAD-DO NOT USE!
+05.0  106    73.50   3060    3743   68276  11818     98.3    1.095  !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    101    70.00   3053    3725   68846  11340     99.8    1.096  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    101    70.00   2717    2951   47112  10796     89.5    1.293

Code:

Cartridge          : .308 Norma Mag.
Bullet             : .308, 180, Swift Scirocco
Useable Case Capaci: 74.595 grain H2O = 4.843 cm³
Cartridge O.A.L. L6: 3.346 inch = 84.99 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Vihtavuori N560 *C

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   94    65.70   2713    2942   42613  11409     92.7    1.357
-09.0   95    66.43   2745    3013   44075  11559     93.2    1.335
-08.0   96    67.16   2778    3084   45591  11706     93.8    1.314
-07.0   97    67.89   2811    3157   47164  11850     94.3    1.293
-06.0   98    68.62   2843    3231   48796  11989     94.9    1.273
-05.0   99    69.35   2876    3305   50490  12124     95.4    1.253
-04.0  100    70.08   2909    3381   52248  12254     95.8    1.233
-03.0  101    70.81   2941    3458   54074  12380     96.3    1.213
-02.0  102    71.54   2974    3535   55971  12501     96.7    1.194  ! Near Maximum !
-01.0  103    72.27   3007    3613   57941  12617     97.1    1.176  ! Near Maximum !
+00.0  104    73.00   3039    3692   59989  12727     97.5    1.157  ! Near Maximum !
+01.0  105    73.73   3072    3772   62119  12832     97.8    1.139  ! Near Maximum !
+02.0  106    74.46   3105    3853   64335  12932     98.2    1.121  !DANGEROUS LOAD-DO NOT USE!
+03.0  107    75.19   3138    3935   66638  13026     98.5    1.104  !DANGEROUS LOAD-DO NOT USE!
+04.0  108    75.92   3170    4017   69037  13114     98.7    1.087  !DANGEROUS LOAD-DO NOT USE!
+05.0  109    76.65   3203    4100   71534  13196     99.0    1.070  !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    73.00   3200    4093   73252  12548    100.0    1.065  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    104    73.00   2825    3190   48168  12163     90.3    1.276