Check the numbers and compare to the list. They may not be the same as FN ones, as I found out about 40 years ago.
I tried 2 different sets. Typical "mauser" mounts that are 45 and 46, and then the Interarms mark X that most suggest using. Those are 55 and 20A. I remember reading some threads here and guys were having a hard time finding the right mounts and that is what was also suggested. I also tried a combination of the 2. 45 and 55, I believe and that was very close to being in alignment, but the scope was pointing upwards. No bueno there. Just got through shooting a few groups with the rifle. It definitely shows promise after free floating the barrel. That was a good move.
Now for the nitty gritty:
The first shot was very low. I had to shoot one of the 10" steel plates at the 100 yard range to see where POI was shifted to after free floating the barrel. Center hold on the steel plate and it still hit below the plate. Around a 6" shift, so there was quite a bit of pressure on the barrel. In this picture, you can see the steel plate I shot at, as well as the paper targets on the backer board. Not a great image though the scope because the camera on my phone was trying to focus in on the back of the receiver. Those targets were literally "flapping around in the wind".
And the real proof of the pudding. On target as per always:
In my mind, it was too windy to be shooting for ultimate precision, but it was a great check to see if accuracy/precision improved after freefloating the barrel. Rifle shows a lot of promise. Now to start developing a load for it, since these were loads I developed in my pre 64 model 70 fwt. It is a great load though, as it has worked in about 7 different 30-06 rifles. I'm pretty happy with my new cheap rifle.. After I develop a load for it, I'll stretch it out to at least 400 yards..