Thought sure I had some information on this, but can't find anything anywhere.

I have a Lothar Walther barrel I got new, but secondhand and threaded at the chamber end. It's a nice barrel, bought it as a 6.5 but checked and it's a 7mm. It's integral rib, tapered full octagon, with integral front sight ramp. I've wanted to make a classic european rifle on it for several years.

A couple of weeks ago I got a 1910 Mexican barreled action. So, thought the time had come for the barrel to be used. I measured the tenon, and it's 1", but threaded 14 tpi. Has a long tenon, appears someone started to thread it for a mauser, but set the lathe wrong and went 14 tpi instead of 12. I drew it up in AutoCAD, and find that I can set up, catch the thread, turn it to small ring mauser, and clean up 3 threads. So, will be able to use about half the threaded length, and will have to set it back about .3".

The only probem is that the reinforce in front of the shoulder is only about 1" long before it tapers to the very thin octagon. If I chamber it for 7x57, the front of the chamber will be about equal with the front of the reinforce taper. Barrel is about 3/4" across the flats there.

Is this enough of a reinforce for the highest pressure that occurs just at the front of the chamber?

Measure a Mauser 93 7mm barrel in front of the receiver ring and that will tell you; they are very thin. 1.8 inches in front of the ring they step to .700. And those aren't even chrome moly steel.
Look at some double rifles; those barrels are quite thin.

Thanks for that info. I was comparing to the Mexican 7mm barrel, and the area in front of the receiver ring is .960; my barrel measures a minimum of .825 to compare. After the first step, which is 1.8" in front of the receiver, the barrel steps down to .820 or so, so is about the same as my blank.