I have a fine 98 Mauser marked on barrel SW.243wxx
I tryed to chamber a .243 round in it and bolt will not close.
With the bolt out with just a empty case the case is stuck in the chamber. It's like this is a custom chambered gun. The chamber is machined smooth. What should be done to find out what I have? I would like to wind up with a .243 out of it.

You will need to do a chamber cast. That 243 has been rechambered to an improved version with the shoulder blown forward. You have a wildcat.

After the casting and it is found to be non-standard such as .243AI. What next? Can dies be made from a chamber cast?

YES YOU CAN .

quote:

I have a fine 98 Mauser marked on barrel SW.243wxx

“I tried to chamber a .243 round in it and bolt will not close”

Rule out an Ackley Improved version, rule out a Wildcat.

Then there is the “I have a fine 98 Mauser marked on barrel SW.243wxx” The SW would have more to do with a street address like SW 457 W 3rd St, then there is the WXX, no clue, but, the 243 is 6mm, there is a chance the rifle is chambered to 6mm Remington.

Problem with confusing the two, the 243 Winchester is a neck down 308 Winchester, the 6mm Remington is a necked down 7mm57, the 308 W case is larger in diameter at the shoulder than the 6mm Remington at the same case juncture from the head of the case, the 308 W case is shorter than the 30/06 but larger in diameter at the shoulder than the 30/06 os at the same juncture, meaning to chamber a 308 W in a 30/06 chamber the 308 W case at the case body/shoulder juncture must be sized down when chambered, not noticed by most because of bad habits.

Your barrel could have been sold as a 243 Winchester with a short chamber, then! the person operating the chamber reamer could have decided to ream the chamber to 6MM. It is possible to get away with ‘it’ with a short chamber, but, if the chamber was 243 W and someone decided to ream the chamber to 6MM there will be a ring on the case after firing, the ring will be where the shoulder/case body was for the 243 W., and it proves again the 6MM chamber reamer will not clean up a 243 W chamber, even though, the 6MM Remington is longer from the head of the case to the shoulder than the 308 W from the head of the case to its shoulder.

And it continues, I know of operators of reamers that have 30/06 chambers that leave a ring around a fired case after firing. again, the 30/06 reamer will not clean up a 308 W chamber, even though. the 30/06 chamber is longer than the 308 W from the head of the case to its shoulder.

A stuck case in the chamber? If the chamber was an Ackley Improved? or a Wildcat? the chamber body would be larger in diameter than the standard 243 W, the Improved or the Wildcat or a Gibbs chamber will clean up the 308 and or 243 W chamber.

F. Guffey

My gunsmith tryed a 6mm Rem. and checked the bore dia. to make sure it was 6mm.
He is going to do a cast and look to try to solve this. The bore scope showed a well cut chamber and good barrel.

Without the chamber cast, everything is just a W.A.G. There are a variety of 6mm wildcats that it could be, the chamber dimensions will tell what it is and hopefully it is something that is a "common" wildcat so dies etc are readily available. If not you will know what it takes to make it a usable rifle.

The easiest route ( for your mental state ) at least & maybe less expensive in the long run would be just to rebarrel that rifle.

The gunsmith called. The rifle is .243, having said that he said it is cut very tight, not just any FACTORY ROUND will chamber.
I looked at his test round and found no issues, his was a hand load FL resized on his dies.
Are factory rounds that varied he said the chamber IHO was fine.

Out of the hand full of factory rounds that I've headspaced I've seen anywhere from .002" to .012" under minimum so yes they do vary but all should be under minimum headspace.

And usually dies will load closer to minimum than factory ammo. Factory is designed to fit in as many chambers as possible. I ran into this with a 264 I had, there was a burr in the chamber so I had it cut and rechambered. They cut it so tight that factory ammo would load (most of it) but not reloads. I tried 2 or 3 sets of dies thinking it was my dies. Ended up having to have them open the neck up more which is where it was tight.

you mileage may vary, if it were me I'd have it fixed so it would take all the factory stuff currently available. a tight neck increases pressure too.

Red

I have been cutting chambers for a long time & I would say that 90% of the time the bolt will close on a new factory round before it closes on a go gauge.

Usually tight chambers are better for accuracy. Why not try a set of dies the same brand as your smith's? I had friends that were brothers that I loaded for. Both had 30-06 rifles, one a Winchester the other a Remington. I loaded on the older RCBS dies, full length sizing. The ammo fit the Winchester just fine, but the bolt wouldn't close on the Remington. I tried this with empty sized cases to rule out a bullet seating problem.

Sounds as though you have a pretty nice rifle with a nice tight chamber...enjoy it.

Make certain that the neck has enough clearence
to release the bullet (Very Important).