308 stock texan long range accuracy?

I am only a paper puncher looking for the best long range accuracy.
I plan to buy a 308 texan to shoot out to 500 yards but after hours of research I fail to find any good feedback on long range accuracy for this gun

I plan to shoot cast bullets from 115gr up to 150gr regarding the barrel twist.

I do not want to throw out my hard earn money for a lemon.
I will also have to sell my fx boss which is a very nice gun out to 150 yards to finance the texan.

I live in Europe and there is other very good big bore guns but the cost is prohibitive (drummen sinner or beaumont), hence the texan seems the way to go for me.

Many thanks in advance for users feedback.