9,3 Schauman Magnum 

A 350RemMag based Wildcat not only for rechambered Mosin Nagant’s

As a result of Finland’s history Mosin Nagant rifles were widely used for military purposes in the past and are still in use for hunting and sport today. It is a natural process under these conditions, that many attempts have been made to convert rifles and the old military round for sporting needs. When additionally the Finnish hunting law between 1934 and 1962 has prohibited calibres for moose hunting smaller than 8mm, a variety of modifications is no surprise.

The good old 7,62 Mosin Nagant cartridge has been necked down to 5,7mm, 6,3mm and 7mm and necked up to 8mm, .338, 9,3mm, .458 and maybe some more. Many of these rounds were commercially manufactured for some decades and some cases for them can still be bought.


Necking up a cartridge gives new life for an old shot out barrel and sometimes improved ballistics, too. At a certain time these conversions were often made by local gunsmiths in Finland. Reboring leads to thinner barrel walls but makes action alteration not necessary if diameter changes are not too radical so that feeding could be a problem. There are also some ex-military Winchester95 rifles in use which were also converted to 9,3x53R or 8,2x53R mainly because their original 7,62mm bore was shot out!

Sporterized Winchester 95 Military Rifles

Sporterized WIN95 &  Mosin Nagant Rifles

For improving a 9,3x53R Mosin Nagant rifle a case with more powder space is needed. ‘Improving’ the Mosin Nagant type case could be one way but a new basic case is a bigger step forward. When the first ideas for this cartridge came up the 350RemMag was not in mind. The magazine of the Mosin Nagant rifle dictates maximum cartridge length and so a case length similar to the 350RemMag is logical. Another point to consider when you are determined to change the case is bolt head and extractor. Surprisingly some Mosin Nagant bolts can handle the common belted case head without any problems but some bolt heads need a treatment like this private solution:

The original 350RemMag ‘suffers’ a little under its COL. In a Mosin Nagant type rifle heavier bullets can be seated so far out that the whole inside volume is usable for powder.

There is a tendency in several countries to ban lead containing bullets for hunting. Lead free bullets of a certain weight are longer than lead containing ones. Regarding this development a larger COL has more future potential.

The 9,3 Schauman Magnum is an inside volume twin of the 9,3x62. That made of course load development rather simple. It is using the barrel lead of the 9,3x53R. Actual measurements have shown that loads for the 9,3x66 Sako are more appropriate due to the superior strength of the magnum case head.

This picture shows a Mosin Nagant barrel rechambered for the 9,3SchaumanMagnum and a 9,3x53R case placed inside. The increase in powder space is obvious.

If you like to know more about the 9,3 Schauman Magnum write to Caj Schauman.