FN49's weren't produced very long. They were design before WWII in Belgium (by John Browning's assistant) but then war prevented them from going into production. They were eventually produced after WWII but were pretty much obsolete by that point. They were soon replaced by an updated version, the FN FAL.
I have one in 7mm Mauser and as far as I know it's the only semi auto 7mm Mauser.? They were produced in a few other calibers for various 3rd world countries. No one other than 3rd world nations needed a semi auto battle rifle immediately following WWII. The US had a huge surplus of Garands (which we gave to allies) and all the WARSAW nations had to buy from the Soviets. There wasn't much of a market left after that.
It's a great gun though and I would put it up against any other semi auto battle rifle from that period.