I have recently got to use my .458 texan at ranges up to 200m & it is the most accurate big bore I have owned. It far out shoots the 9mm samyang I used to have. The trigger is a dream & accuracy is better than I thought. I have found a 350gn. round nose bore riding front area cast lead the best so far as I also shoot a .458x 2 inch powder burner so have plenty of moulds to experiment with. I can go up to 400gn but trajectory is a bit high. I have fitted a Cold Shot scope elevation adjuster to save twiddling the scope which is not good for the very fine brass screw threads. As the elevation has to adjust to the 6m drop of this bullet at the 500m gong this is a bit hard on most scopes internals.
Have any readers found good accuracy increasing secrets as the long 34 inch barrel does increase the harmonic dwell time & I am adjusting the front barrel weight vibrating unit I fitted but this is an ongoing project with different weight bullets & air pressure.