I posted a question about GameKing performance in the field and noticed the discussion drifting towards question of velocity. So here's the next question:

Based on those responses it seems that the GameKing has a definite velocity limit. And apparently a 300WinMag is capable of exceeding that limit, leading to potentialy poor performance.

So let me ask this: What's the upper limit for these bullets? Do the limits vary between weights? Just curious because if the limit is the same for all then most likely I'll be safe with the heavier ones (180 or 200gr). If I can't load the GameKing to the desired fps I'll have to try something else. Too bad because 1MOA with a hunting bullet is so tempting.

All conventionally designed boatail bullets have a design flaw which limits their performance. The tapered boatail jacket renders them unable to hold their cores in place as well as their flat base cousins. For this reson, Speer doesn't bother making their boatail hunting bullets with their Hot Core process.
As a rule, Sierra big game bullets perform best at impact velocities of 2100-2800 fps., like other conventional bullets. Try Sierra's tech line for more details.
Unless all your big game hunting will be on deer class stuff, or at ranges over 200 yds., I suggest you try one of the premiums, like the Nosler Partition for your rifle. Personally, I use nothing but premiums on big game of any kind. They are much more consistant, and allow me to take bad angle shots. E

Are gamekings boat tails?
I'm looking at a recovered one right now that is definately a flat base.

Boileroom;
It would be my guess that what you're looking at is a Sierra "Pro Hunter" a flat base, and the Sierra "Game Kings" are the boatail configuration offered by Sierra. Someone correct me if I'm wrong.
Marsh Mule

pro-hunter is flatbase and GK is boat tail.

This is what I thuoght til I seen the recovered bullet. On the box it shows the Game king as a boat tail. The recovered is a flatbase, no doubt about it. Could I be ripped off? I wish I had a digital camera to show everyone.
There is no chance I mixed up ammo because the two types of factory ammo I bought were Fed. Prem. Game kings and Win. Supr. Silvertips wich are loaded in silver cases. Both bullets are also easy to tell apart. Maybe they got mixed up at the store. At Fed. maybe? Ive just been out to my barn to double check and the box says Game king!
I'm pissed off!

some people I know say the pro hunter is the better bullet.

Boileroom;
That was factory loaded federals? I'd contact them and inform them of their error! If you have the means to pull one of the bullets you have on hand to confirm your findings, then contact them. Maybe they will send you a box or two of fresh, correctly loaded ammo! Worth a try. I'd be curious to know their reply also.

I've shot all the factory ammo I've bought for the brass. I just loaded my first batch of loads for pressure testing. I might get out tomorrow.
I can maybe let them no the lot # and see if anyone else has dicovered this.
I know I have pulled ammo out at the shop and taken a look at what I'm buying. How many times does it happen do you think.
It killed him on the spot so I guess I can't complain about that very much.
I only have the jacket now.
Got to go, Vancouver just scored on Minnesota.

GFP,

I agree with Erimicus in that a Boat tail will suffer seperation much sooner than a FB. The taper in the shank is at the bullets most critical point where core to jacket strength becomes a real issue and it significantly weakens the bond. Try some other bullets..
Ive had very good results with FB Hot cores from a 7mm RM. I would try them or a Mag tip. Even a Pro Hunter should hold up better with close up mag shots than a GK.

They performed well at 2900, I won't go higher

Gonzo: I don't have a lot of practical experience with the 300 Win and either 180 or 200 Gr. GK's. I've used a lot of GK's in 7 MM or 375 calibers. They usually put the game right down, but almost everyone came apart even at 2650 muzzle velocity. They were devastating for deer, but exploded on heavy bones of larger animals with little penetration.

I've used the 200 gr GK in a 300 Wby at nearly 3000 fps. No problems so far, but I also haven't had to bust any large bones with them. Great accuracy though. - Dan