identifying old barrel

????????? The manufacture is listed (Schultz & Larsen) as well as the model (54)
The 7x61 Sharpe & Hart is what its chamberd in.

The 7X61 was a popular round back in the day.

would you be interested in selling?

If OP builds that into a rifle to hunt or just use for range work, 154-160gr spitzers and a good dose of IMR 4350 or H4831 will be very pleasing. That is a NICE barreled action you have there.

That is a rather interesting barrel and receiver. I say interesting because it calls for a bit of amateur detective work. By way of background: I once had a Schultz & Larsen M-54J rifle in 7-61 in Sharpe and Hart caliber, which was a beautifully finished and slick working sporting (hunting) rifle. I also had a S&L .22 RF target rifle made for 50M 3-position competition. S&L was better known for their International (Olympic) free style 300M CF rifles than for their hunting rifles, especially in European rifle competition circles. Their 300 M "free" rifles were recognized by their thumbhole stocks and hook buttplates, as were other makes of free rifles, but the S&L rifles were noted also for their beautifully finished M-54 actions which featured rear bolt locking, which made operation especially slick and easy. (Attached is an old photo of Niels Larson, holding one of their target rifles. Most of which where chambered for the 6.5 Swede, which was a popular 300M target cartridge at that time.) The 7-61 Sharpe & Hart cartridge was the brainchild of Phil Sharpe, who is best known to Americal shooters and reloaders as the author of books and numerious articles on rifles and reloading. His 7-61 S&H was a 7mm round based in a belted magnum, with ammo loaded by Norma. Ballistics were similar to Remingtons 7mm Mag, and it was not a target cartridge by usual defination and use. Which brings us to the mystery of the OP's barreled receiver, which has a dovetail scope base attached and typically used with target type scopes of that era, leading me to suspect of the rifle was made for target shooting. Further reinforced by what can be seen in the OP's pics of the barrel's chamber area, which shows no forward taper in chamber area typical of hunting rifles, which suggests the barrel has a heavy target contour. The OP can answer this question. Another hint is that the S&L hunting rifles were marked 54J whereas their target rifles had a simple 54 receiver stamp, as does the OP's receiver. But if the OP's rifle parts are actually from a target rifle, why was it chamberd for the 7-61? Which is not a typical target caliber. So, my speculation is that the rifle might have been built for 1000 yard target shooting, for which the 7-61 would have been an excellent caliber. Attached is a pic of a long range target rifle with S&L M-54 action, note target scope base on front of receiver, same as OP's. Feel free to join in, or laugh at my offhand amateur speculations.
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Wow!

Here's a postwar photo of Capt. Phil Sharpe holding a Stg44 with a krummlauf device: