Ledd Slinger
Silver $$ Contributor
Recently received my new custom hydraulic form die from Whidden for my 300 Norma Mag Improved and thought I'd post my results.
This is my first form die and it seems to work pretty well. My Improved version of the 300 Norma utilizes a 35 degree shoulder and only has .018" total body taper from the case .200" line to the shoulder.
The die does not produce nice sharp shoulder angles like a case fired in the rifle will, but it does a pretty good job of forming the 35 degree shoulder. However, my main reason in wanting the forming die was to get the body taper out of the virgin 300 NM cases prior to firing. A standard 300 Norma case has about .010" less diameter at the shoulder than my Improved version (.560" vs. .570"). Without removing the body taper on a case prior to firing, the round cannot sit centered in the chamber very well when testing 'jump' seating depths. In regards to body taper, the hydro die produces brass with a shoulder diameter that is nearly identical to a fired case so it is doing exactly what I want. And of course the internal case capacity after hydro-forming is also much closer to a fired case. Hopefully this will allow me to trust the accuracy and speed results on unifired cases with a little more confidence.
The instructions say to give the forming die "2-3 light to medium strength strikes" with a hammer. This does not work very well on the big Norma case. Having only tried water, I found that I have to use a good size framing hammer and 5-6 fairly stout strikes to move all the brass where it needs to be.
Pictures of results below.
LEFT: Virgin 300 Norma Mag case
MIDDLE: 300 NMI Hydro-formed case
RIGHT: 300 NMI fired case
Shoulder diameters of all 3 cases. The hydroformed case almost matches the exact diameter of a fire-formed case. Order of cases is the same as above.
Virgin brass
Hydro-formed brass
Fire-formed brass
This is my first form die and it seems to work pretty well. My Improved version of the 300 Norma utilizes a 35 degree shoulder and only has .018" total body taper from the case .200" line to the shoulder.
The die does not produce nice sharp shoulder angles like a case fired in the rifle will, but it does a pretty good job of forming the 35 degree shoulder. However, my main reason in wanting the forming die was to get the body taper out of the virgin 300 NM cases prior to firing. A standard 300 Norma case has about .010" less diameter at the shoulder than my Improved version (.560" vs. .570"). Without removing the body taper on a case prior to firing, the round cannot sit centered in the chamber very well when testing 'jump' seating depths. In regards to body taper, the hydro die produces brass with a shoulder diameter that is nearly identical to a fired case so it is doing exactly what I want. And of course the internal case capacity after hydro-forming is also much closer to a fired case. Hopefully this will allow me to trust the accuracy and speed results on unifired cases with a little more confidence.
The instructions say to give the forming die "2-3 light to medium strength strikes" with a hammer. This does not work very well on the big Norma case. Having only tried water, I found that I have to use a good size framing hammer and 5-6 fairly stout strikes to move all the brass where it needs to be.
Pictures of results below.
LEFT: Virgin 300 Norma Mag case
MIDDLE: 300 NMI Hydro-formed case
RIGHT: 300 NMI fired case
Shoulder diameters of all 3 cases. The hydroformed case almost matches the exact diameter of a fire-formed case. Order of cases is the same as above.
Virgin brass
Hydro-formed brass
Fire-formed brass
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