Ed,
I've taken quite a few Muledeer with the Gamekings, I've taken 2 bucks with a 100g Sierra GK out of my .243 AI, 2 using a 150g GK out of a 7mm Rem Mag Sendero (I don't have this rifle any more) Several Bucks using 165g GK out of my .30-06 before and after I built it into a .30-06 AI. and 1 Cow Elk with a 165g GK also out of the Standard .30-06 Springfield.
My father also likes Gamekings out of his 7mm Rem Mag and .30-06 Springfield both Ruger no.1s. Both 150grns as well.
We have never lost an animal to a Gameking, They are very accurate, almost as accurate as Match Kings and held to very tight tolerances. They are a cup and core bullet, but they have all done quite well.
It seems that for the .30-06 a 165g GameKing loaded to 2700-2800 FPS is a match made in heaven. Many deer have been taken with this combo.
Right now I have a load for my 7 STW using a 160g Sierra Gameking Hollow point over 77g of IMR7828 (seated to fit the magazine) that shoots at about an inch out of my rifle. It was a generic load that I put together to get the rifle on paper this last fall. I wouldn't hesitate to shoot a Big muley buck or even a huge bull elk with this load. It would drop them like a ton of bricks.
My problem is that I keep chasing the most accurate load for both targets and hunting. Some of my best groups have been with Sierras, I've been able to get Bergers to shoot tighter groups. Both are well under an inch, but the Bergers out shoot the Gamekings. I don't dare hunt with Matchkings, as I've heard about penciling and other bad things happening with them.
So as far as accuracy is concerned, Berger wins in my .30-06 AI. Hornady won in my 6.5-06 AI (which my Father now owns), Sierra wins in the .243 AI and my Father's .30-06 Springfield and 7mm Rem Mag . Sierra also wins in my .243 Win Varmit rifle, it shoots 75g Hollow Points.
Sierras are great bullets. They perform quite well on Big Game and are easy to get to shoot. bergers perform quite diffrently, but Dead is Dead and if you can drop them in their tracks it's an awesome feeling. But both will get the job done. If you have reservations about these two bullets go to a 160g Nosler Accubond.
The bullets that the outfitter recommended are all good elk bullets, but the question is, can you get them to shoot with the level of accuracy that you desire?? I agree with the bullet weight thing as it gives something of a fudge factor for erronious shooting, but they may not shoot well in a standard 7 mag, they may do well in your 7 stw. Most outfitters are dealing with clients who don't shoot very often or have problems with buck/ bull fever. I've had friends I've taken who have the same issues. It definately makes things interesting and usually I'm having to work harder for something that wouldn't hve been that bad had they made a better shot. Guys like us who do lots of shooting can place shots with precision. Those 160g Sierras will do very well if you put'em in the lungs or heart, a liver shot will kill'em very quickly as well.
Sorry for rambling on....
Dan