And yet you still provide no useful information, and apparently haven’t even looked at a picture of
The barrel end.
Given when it was designed and who designed it might be inch thread,
But given who manufactured it it could be metric.
However it appears I have found a barrel chambered in short
I've looked at several. Have two in my locker.
But you insist that I must be useless, because I said to measure off the part you have in hand.
Ain't you gonna feel like a frikken moron, if that barrel does not fit, eh?
Make sure you get the proper "Short" parts that go with, too. I'll let you figure out what they are. LOL! FWIW the "Short" barrels were 1 in 22 twist rate and don't stabilize a LR worth a shit. Do you want a Short gun? LR barrels were 1 in 16 twist.
These things have been made in Belgium, over several generations of models, ranging from pretty basic, with a hole in the stock at the top of the wrist, through the more modern 'feed through the side of the stock' models, and Japan, as well as by Remington. Plus the Chinese clones, and like as not, others. Nothing gonna work quite as well as fitting the parts to the ones you have in hand! Thus my comments to the effect of "Fit it to what you have!"
Your timing and feed are dependent on how deep you make the barrel tenon sit. You have, more or less, one thread pitch to work within, and the barrel nut does the rest. Off the top of my head, I would suggest looking at something around a quarter of a thread pitch longer than what you can measure directly to the bolt face, but it may be one full turn past that. Still wrapping my head around it. Again, a plug gage tells. It may not actually be that critical, again, due to the nut.
Make the plug gage, and know, rather than hoping. The pitch is easy to measure, and you likely have no business mucking about with guns if you are too dumb to use a thread pitch gage.
Same goes for the thread angle. Shine a light in, and see how the gage looks against the threads and decide. Probably 60 degrees, but who knows. Check.
The outside dimension for the two extractor hooks (You have two right?) can be worked out by their outside dimension, the inside, same via the inside dimensions of the extractor. The extractor slides up and down on the bolt a bit. Work out a workable angle using the same plug gage you used to check out the threads. You can always cut deeper, esp on the test piece.
Still think I'm stupid, or are you starting to reconsider? Either way, good luck! These are great little rifles, I have lots of good memories dating back almost 45 years, and figure that if any gun is worth putting a bit of effort in to, it's probably as good as any to do to.