Vihtavuori powder for .257 Weatherby

[SenderoAg]

Trying to find some Vihtavuori data for the .257 Weatherby - 115 Ballistic Tips............they have .240 & .270 data listed - but no .257 Weatherby.

Anybody know a starting and max for the N568, or where I can find the data.

I tried to reach out to Vihta - their process for asking questions is like asking the government about UFOs. Fill out a form and wait............

I've got a load using RE-25 - but it's temp sensitive and weather changes every 15 minutes here in Texas.

Thanks for the help !

 

[DrMike]

Cartridge          : .257 Weath. Mag
Bullet             : .257, 115, Nosler BalTip 25115
Useable Case Capaci: 76.471 grain H2O = 4.965 cm³
Cartridge O.A.L. L6: 3.170 inch = 80.52 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Vihtavuori N568 *C*T

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    67.14   2987    2279   43882  15243     94.3    1.371
-09.0   92    67.89   3025    2337   45501  15442     94.9    1.348
-08.0   93    68.63   3064    2397   47174  15634     95.5    1.325
-07.0   94    69.38   3102    2457   48908  15819     96.1    1.302
-06.0   95    70.12   3140    2517   50705  15997     96.6    1.280
-05.0   96    70.87   3178    2579   52569  16166     97.1    1.258
-04.0   97    71.62   3216    2641   54502  16328     97.5    1.237  ! Near Maximum !
-03.0   98    72.36   3254    2704   56508  16480     97.9    1.216  ! Near Maximum !
-02.0   99    73.11   3292    2768   58588  16624     98.3    1.196  ! Near Maximum !
-01.0  100    73.85   3330    2832   60746  16759     98.6    1.175  ! Near Maximum !
+00.0  101    74.60   3368    2897   62987  16884     98.9    1.156  ! Near Maximum !
+01.0  102    75.35   3406    2963   65313  16999     99.2    1.136  !DANGEROUS LOAD-DO NOT USE!
+02.0  103    76.09   3444    3029   67728  17104     99.4    1.117  !DANGEROUS LOAD-DO NOT USE!
+03.0  104    76.84   3482    3096   70237  17199     99.6    1.098  !DANGEROUS LOAD-DO NOT USE!
+04.0  105    77.58   3520    3163   72844  17283     99.8    1.080  !DANGEROUS LOAD-DO NOT USE!
+05.0  106    78.33   3557    3231   75553  17356     99.9    1.062  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba    101    74.60   3468    3072   70164  16727    100.0    1.102  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba    101    74.60   3251    2698   55933  16745     96.4    1.218  ! Near Maximum !

 

[SenderoAg]

Thanks very much !!!

 

[phil]

It seems common to get about all the case will hold with a drop tube, and you are within a grain or two of ideal…and max. But start low obviously and work up as normal.
It’s been very stable and predictable for me in 2 rifles, and lacks the erosion rate of n570, along with slightly reduced velocity. Maybe 50- 75fps?
Big roomy cases are a natural fit.