I have a 7mm rem mag and a 300 wsm both are great calibers but for an all around gun I think the 300wsm is the best out there.Better bullet selection and in a short action rifle and all the performance of the 300win mag
Run the ballistics on any on-line ballistics program. Hornady has one on their web site. The 7mm bullet is really hard to beat for Ballistic Coefficient.... and maybe Sectional Density. It's been some time since I've looked at those numbers....so I'm going off of memory....but if you run the numbers.....that will tell you a lot.
I have both the 7mm and the 300WM, not the 300WSM. On deer you do not see any difference - maybe a little over kill here. I have shot elk with both and each has done fine. I have now used the 300WM exclusively on elk for the past several years and really prefer it over the 7mm as do my sons. Both work on elk. But so does the 30-06's that we used for years.
IMO the 300 is a better choice simply because of the selection of bullets. You have a good bit wider range of bullet weight available also. There are some times when the heavies for the 30 caliber can really pay off. And it is with the heavies that the 300 WM really shines. Even slightly over the 300 WSM.
Someone above said compare the 300-180 grain bullet to the 7mm-175 grain bullet. However that is not really a fair comparison. The real comparison is to compare the 7mm 175(sincer it the largest available) to the 30 caliber 200 or even 220 grain bullet. The BC's on those big 30's are not too shabby. And the 200 grain 30 caliber is going to have better sectional density than the 7mm. As well as simply a little bigger hole.
When comparing the two cartridges I think the 300 wins a Gold Meal. But the 7mm is jut behind with the Silver Medal. Tom.