Using Vihta Vuori Oy powders in the big overbore cartridges

Discussion in 'Reloading' started by JKO, Jan 27, 2006.

  1. JKO

    JKO Well-Known Member

    Jan 22, 2006
    Do any of you have personal experience relating the use and performance of Vihta Vuori Oy powders in the big overbore cases ?

    I'm talking about the .378 Weatherby Magnum, .404 Jeffery, and .416 Rigby-based cartridges, both factory and wildcats.

    The loads I currently use in my .30 Cody Express (.30-416 Rigby Ackley Improved (40-degree shoulder)) are based around Hodgdon's H870, but I was curious as to how the VV powders--N170, 20N29, and 24N42 in particular--compared with the Hodgdon powders (H870, H1000, H50BMG), as well as comparable powders by other manufacturers.

    Mostly, I'm curious about safe pressures, accuracy and velocity, but ease of cleaning is also important.

    I understand that every rifle is different, so I don't expect any loading data, unless someone cares to recommend a good starting load for the .30-416 Imp. using a moly-coated 200-grain SMK, in a 36" long, 1-in-9" to 1-in-9.5" (RHT) barrel.

    (The rifle was purchased secondhand, from the original owner--the action is a modified Remington 721 Magnum action (SAKO extractor); the barrel is a 36" K&P Stainless Steel, 1.25 inches in diameter, and unfluted. The twist rate was ESTIMATED using a cleaning rod and a lightly-oiled patch.)

    Thanks again.
  2. brianwinzor

    brianwinzor Well-Known Member

    Jan 31, 2003
    JKO, I have only used Vihtavouri N170, as the Oz agents so far haven't imported the 2 slower burning powders 20N29, & 24N42.

    I have not used N170 in a large cased big bore, only in my 25/06 AI with the 142 and 156 grain Wildcats. I have listed below my chrono results which will give you an idea of the burning rate in relationship to H870, AR2225 (HRetumbo in US), and Re 25.

    25/06AI - Wildcat 142 grain ULD
    57.0 Re25 2927 Normal Pressure
    58.0 Re25 3011 Near Maximum Pressure
    59.0 Re25 3042 Max Pressure, 95%load density.

    60.0 AR2225 2914 Normal Pressure
    61.0 AR2225 2986 Near Maximum Pressure,
    62.0 AR2225 3039 Max Pressure, 100% loading density

    61.0 VihN170 2928 Normal pressure
    62.0 VihN170 3020 Near Maximum Pressure
    63.0 VihN170 3096 Max Pressure, compressed load

    64.0 H870 2953 Near Maximum Pressure
    65.0 H870 3018 Max Pressure, 99% loading density

    Nb: bullet did not stabilise due to 1 in 10 twist.
    25/06AI - Wildcat 156 grain ULD
    57.0 AR2225 2782 Near Maximum Pressure
    58.0 AR2225 2810 Max Pressure, 95% loading density.

    57.0 VihN170 2700 Normal pressure
    58.0 VihN170 2773 Near Maximum Pressure
    59.0 VihN170 2820 Max Pressure, 97% loading density.

    60.0 H870 2705 Normal Pressure
    61.0 H870 2725 Normal Pressure
    62.0 H870 2771 Near Maximum Pressure
    63.0 H870 2832 Max Pressure, 99% loading density

    Nb: bullet did not stabilise due to 1 in 10 twist.
    So far I have only used VihtN170 in the 25/06AI, with the 115NBT, 130, 142, and 156 UlD Wildcats, and pressure build up was commensurate with the load increase, and it certainly did not appear spiky. I did not notice that it left any more fouling than the other powders in the test.

    So far in limited testing of this powder, accuracy has been acceptable without being outstanding. However, further testing in a soon to be built 224 Clark, and 25/7mm Dakota, will give me a better idea of Vihtavouri N170. Hope that the above is of some help. Brian.

  3. uncleB

    uncleB Well-Known Member

    Aug 19, 2005
    since there has not been too much response I will throw in my 2cents the only vv powder you mentioned that I have tried is N170 it is a very slow burn rate powder, too slow for my 338 Lapua Mag Imp.(it likes RL25). since a 30-416 Rigby is wildly overbore N170 might be a good place to start but dont try too many powders as your throat life will be very short. dont even try H1000 it is way too fast if you want to try Hodgdon start at Retumbo and work to H50bmg . I have heard that 20N29 works well in this application but have never talked to anyone that has shot 24N42