A lot of good observations above.
If shooting factory ammo, the 25:06 is optimum with 120 grain bullets and generally they go somewhat faster than the optimum bullet in the .270, which is 130 grains. So, a little flatter shooting with the 25:06 and a little more bullet mass with the .270. Either is great for the deer shooting you are doing.
If you reload, the following may help. The .270 nicely can be loaded up to a 140 or even 150 grain bullet (somewhat farther from optimum as weight goes up) and also down to 120 or 110 grains with decent results. No experience lower than that.
The 25:06 can very nicely be loaded down to 110 or 100 grains (and maybe less) for other shooting purposes, but somewhat less optimum overall as weight goes down.
I have never loaded the 25:06 heavier than the 119/120 grain bullet, so have no experience from which to opine. But, 130 grain might work OK.
Hope this helps with your decision.
