From the loading manual I have it says that a 300 win can push a 180gr bullet at3019 fps with the max load of Imr 7828 76 grs. If you are shooting 81 grs of powder instead you might be getting the speeds you quoted but I would think it is a little tough on a gun at 5 grs of powder over the max load.
Lets compare apple to apples in bullet weights and powders.
7mm stw 300win
140gr 140gr
Imr 7828 IMR 7828
3473 fps 3340fps
SIGHTED IN AT O AT 250yards for 400, 500, 600 yards
-10.59 -12.99
-23.69 -29.38
-42.52 -53.43
Energy at 500 and 600 yards
1888 1415
1622 1167
Now with all that info which is right out of the book I see a big difference. All info is comparing equally and from that I can see why I prefer my STW over a 300 win. Either way it doesn't matter what others think. It's my gun and I think it does a better job than my 300 and see a huge difference. Have a good day