So I'm still considering a Browning/Winchester 1885 in 7mm or 300 Ultramag (depending on donor rifle). Haven't seen one yet, and I'm a little wary because of the minimal chamber wall thickness.

Winchester did make some WSM 1885's recently, and the WSM's are slightly larger than the Ultramags. My question is - does anyone know if the barrel thread dimensions or metallurgy is different in these WSM guns than the other Browning/Winchester 1885's?

(I know there are better choices for an Ultramag, but there's something about those Hi-Walls that I cannot resist)

That sounds like a nice build. I recently sold a Winchester 70 300 Ultra mag that had never been shot. Still have cases, dies and everything to load it. I had really intended to keep it, but the offer was too good. Now, like you, I am looking for an ultra mag and don't want a Remington.

The 1885 barrel shank OD is .935. Did they enlarge it for the WSM? I don't know, but I doubt it.

They did change the barrel tenon dimension when they began chambering the WSM. It is 1-32 UNEF.

Learned something.

Well that's not good, because it looks like Brownchester was also concerned about the chamber wall thickness so they went with finer threads to increase the distance from the chamber to the thread bottoms.

Cantshootalick, do you know if they retained the fine theads for the later 1885 Safaris? (300 & 375 H&H's)

If memory serves me, it is across the board.

How's that rebated rim work in the 1885?