IIRC the 7mm chambering was most common. The 7 X 57 cartridge is perfectly adequate for hunting (WDM Bell killed over 1000 elephants with this round). The other chamberings are nice, but much sought after by collectors and such examples are much pricier.
I have always wanted an FN-49 in 7 X 57 to compliment my two Spanish Mausers. The 49's are getting old and parts difficult to find. The design had a few fragile parts that have made these rifles into nice collectables rather than frequent shooters.
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