got it, thanks for the infos everyone. the reason why i wanted to change the barrel by the way is to put a long eye relief scope on it. my idea was that the barrel has a place to add a rail like on some scout rifle contours. the receiver is dovetailed cut and the rear sight is very shallow... as for the caliber. i was very confused by what was written on the lee hand loading tool. i also got some dies for .303 british but yeah i just thought that if the ammo used was indeed .30 cal instead it would be much easier to find with much more selections to choose from. that cartridge is really confusing...
A few decades back in time, a couple of friends and I took a couple of surplus Springfield O3 barrels, which could be had super cheap, and cut back the chambers on them enough to thread the tenons and chamber them for the 303Brit case.
We wanted to get away from looking for proper sized bullets, whose bores varied from one rifle to another, often drastically.
We neck sized the cases using a .307 diameter expander ball so that the 308 diameter bullets, which were readily available as surplus or commerial could be utilized and without so much frustration.
Those were both incredibly accurate No4s, with those NOS surplus O3 barrels fitted.
I sold mine to a local fellow that passed on last year and last summer his son was using the rifle to hunt Deer with, because "It used to be really accurate when his DAD shot it"
He hadn't bothered to learn how to reload and after using up all of the ammo his father left behind, was using off the shelf ammunition, with .312 bullets.
I was surprised that they even chambered but remembered we didn't get a reamer made up for the smaller diameter necks.
His groups were appx 6 inches (12cm) at 100 yards.
This isn't a dangerous condition IMHO but the oversize bullets obviously weren't happy being swaged down that much in the process of firing.
I made arrangements for him to come over and get some coaching on reloading cartridges for his rifles.
He had half a dozen rifles, with brass and components on hand for all of them. He's never been the most enthusiastic person about anything, so I wasn't even expecting him to show up.
All of his firearms came from his father. He's never been able to afford to purchase any.
I told him to only bring his father's reloading notebook and the powder/bullets/primers/dies I knew he had on hand, for the No4.
He actually showed up and was even enthusiastic, turned out I had to change my view of him. He's a nice guy, but super shy.
Anyway, we put his dies into a press that is identical to that from his fathers bench and loaded up a hundred rounds for the No4 with a 308 diameter bore, using his father's recorded data.
We took the rifle to the range, after a thorough cleaning(another much needed lesson) and the rifle settled right down to slightly over 1 inch (2cm) groups at 100 yards, after appx 5 fouling rounds.
The fellow was very happy.
It turns out he moved into his father's house, after he passed and the room the firearms safe/reloading equipment was left untouched.
He's a nice fellow, two nice kids and a nice wife. The house is close to 50 years old but it's sound and has a good roof.
This is the first time in their lives, they haven't had to pay rent. He's managed to pay of all of their debts with the extra money on hand and even after some house repairs/taxes/insurance, he's managing to put money aside for retirement. Good on them.
EH, sorry for wandering off the topic, I was just trying to throw out that you may want to look at a .308 bore take off barrel to fit to that No1 you have. It would make your endeavor so much easier in the long run.
The difficult part will be finding a smith with the knowledge and a reamer to do the job.
