The tipped bullet was offered simply for marketing. Many of todays "hunters" think they "must have" tipped bullets because Biff and Buffy on Latest & Greatest Outdoors TV Show said they did!
Ballistics wise, I doubt seriously you'll see any difference between the TSX and the TTSX in your rifle. Performance on game wise, there is NO difference. The Barnes X family of bullets are THE best big game bullets on the market IMHO. I've shot X-bullets in everything for well over a decade and I've NEVER lost the first animal with anything shot with a Barnes, I can't make that claim for anyother bullet in my nearly 30 years of hunting.
The good thing about Barnes is you don't have to go up in weight for weight retention or penetration. From your 300 the 150TSX will penetrate equally and many times out penetrate the majority of 180s on the market. This allows you to shoot lighter bullets for better velocity (spelled better ballistics) without giving up on game performance. The 165TSX would be a mighty good pill for your 300, and honestly for deer if you got some 150s from someone like Conley Precision, you'd still be MORE than equipped. Since 1999 I've shot ALOT of whitetails (30+) plus a muley and antelope each with the .30 cal 150Lazerhead (modified TSX) at 3800fps from my Lazzeroni Warbird and the results are simply PERFECT! Including one double shoulder shot at 27yds on a big buck to a 300yd "TX heartshot" doe that had one hole in each end of her and she went down so quick I didn't see her fall. The bullet simply WONT fail and WONT disappoint you!
Getchusum,
HL