Extending the throat on say a 7mm mag or any other 7 is a simple matter, but a piloted throating reamer, complete with extension and handle. For Remington 700 I make an 700" to .704" aluminum sleeve with a .437"hole that fits the throating driver reamer rod. And a drill stop. Cutting oil in the barrel & on the reamer insert, feel the reamer stop..move the stop collar up to the aluminum sleeve, back off and insert say .025 feeler gauge, lock collar, and turn buy hand to stop...clean and measure how much the bullet has moved out of the cartridge case. Make a dummy round grind or mill away part of the neck to see where the particular bullet boattail is in relation to the shoulder and neck. Go slow until you get the desired results with respect to mag length...putting short action cartridges in long actions has been done for a long time. I do long action 308 for huge gains with 200 to 230 gr bullets. So you 7 Rem mag fans can do it yourself with just a throating reamer, it's really easy.
I got rid of my 7 mag as the guy in the video I wanted more diameter for elk hunting and went to the 338, and 358, dia cartridges for hunting were more effective for me...but a long time ago I killed a number of elk with a 7 mag...so you can too obviously, but I'm not a fan of long "shooting" at big game animals. I bow "hunted" for 10 years, and for me it's about hunting. Shooting is a different endeavor and requires no hunting/stalking skills.
So in my old age I don't hunt much but do alot of shooting at different ranges. An elk hunting friend drew a tag New Mexico to kill a big bull with his new 28 nosler a long range shooter ... killed a very nice bull at about 70 yds...I call that good hunting...good shot placement, and ya don't have to worry about wind deflection or the downward trajectory of the bullet, as you have to strike higher in the kill zone as the bullet is coming down at a such a steep angle it will drop out of the vital zone before complete penetration is achieved.
And that is for sniper school not big game animals. In my opinion ... do what ever is legal...mostly...but remember it's easy to extend your rifles throat to take over 4.00" COAL cartridges, if ya want ...I have, you can too...or buy the 7PRC...but you can extend that throat too...if ya want to..