I shoot the same gun, same caliber. For factory loaded ammo my t3x loves the Precision Hunter 162 eldx. That combo is more capable than I am distance wise presently...but im comfortable with it to 500 on deer size targets with minimal wind.
Cow elk I shot last year was good broad side behind the shoulder shot from 250 yds. She ran to the herd about 20 yards and fell over. Guide told me to hit her again as she was still kicking a bit and it was getting dark and wanted to be sure she was done...second shot totally unnecessary, but I did as told. not much blood till opened her up, then no doubts bullet did its job
I plan to take that same combo after moose in Newfoundland next year. With proper placement the ELDX is extremely lethal, borderline explosive in chest cavity...but it can be more unforgiving at closer ranges with especially with bad placement.
I'll take that same bullet in 143gr. in my wife's 6.5creed after deer, antelope or elk to 4-500 yards any day, no questions asked.
Her's is t3x as well and shoots factory 143 eldx better than anything else we've tried as well.