I have a 358 win. based on a military model 98. The bolt and receiver are non-matching. The bolt is exremely sloppy, swinging back and forth an inch or so (it seems) when in the far rearward position.

But I can shoot 5 shots touching at 100 yards with it. And that was with a stock that was broken at the pistol grip and pinned/glued back togehter. I feel that such accuracy from such a rifle is unexpected, but there is no reason to complain.

500, as you are aware I am interested in a longer range rifle at some point in .338 lapua magnum and my Gun Smith told me that he can build a "darn accurate .338 lapua rifle" on a cz 550. He said as long as I fork out for a premium barrel it will be fine. He feels that it is more in the barrel chambering alignemnet etc. more so than the action used.

So your rifle must be very well chambered and have a good barrel !!

Aside from popular belief, that swinging side-to-side of the bolt is completely irrelevant to the accuracy potential of your Mauser. When it counts, is when it is locked up with the barrel in the fire position. Matching numbers on bolts and receivers is another misconception of a quality action. It's great for collectors, but as long as the two parts mate with each other accurately, that is all that is necessary. This is something that gets done all the time. 90% of all accuracy problems will stem from a sloppy chamber with excessive headspace, or one that is not running concentric with the reciever. You'd be surprised as to how well you can shoot a receiver who's lugs are not lapped or square, but has a tight concentric chamber with minimal headpspace. You can take the finest, most accurate action in the world, and it will shoot like a turd with a bad barrel, and I mean a bad chamber, not necessarily a low-quality barrel. Tight chambers in factory barrels will prove to be quite amazing in the accuracy department, when executed properly. You don't have to spend $300.00 on a barrel blank to shoot varmints out at 500 yards.

An inch from side to side!

That mismatching bolt must have tightened it up 100%.

As Melvin Forbes once told me, "Everything behind the locking lugs if fluff. It is simply used to transport the shell from the magazine to the chamber and back out again. If it was necessary, cannons would have them."

That was good enough for me. I know it is also for gas deflection and safety, but not true function, so an inch of play out of lockup is no problem and as 1894 said, how did you get it that small?

Military Mausers have a lot of play when the bolt is fully open, they were designed this way so that the mud and muck encountered in combat would not bind the action.

If it ain't broke, don't fix it.....and yours ain't broke...it functions flawlessly no doubt, and shoots great, so ???????????