Twist rate on a 16 inch PTR 91 SC model?

[Imonyurl3ft]

I just got a PTR 91 squad carbine model with the 16 inch fluted bull barrel and I'm not sure the twist rate on it. None of that information came with the gun as far as I know. I tried looking it up. I believe the 18 inch barrels have a 1 in 12 twist and the 16 inch barrels have a 1 in 10 twist. If anyone could let me know I'd really appreciate it. I'm trying to find the right bullet weight for my rifle but I don't know the twist rate. Thank you.