I have no idea on the round count through the original barrel. I bought the gun used in the late 90's for $200. A little research shows the gun was made in the very early 60's. It was still shooting very well when I took it to Kevin Cram to accurize it. His barrel scope allowed us to see the throat erosion was becoming pretty extensive so I decided to rebarrel it while he had the gun.
I shoot a factory remington 700 sps varmint, with factory 80 grain seirra soft points. The purpose of purchasing this rifle and buying this ammo instead of reloading was cause i wanted to get some coyotes quickly, plus i wanted a good long range over the counter 6mm incase i didn't have the time to reload. I was going to build off this action and custom this rifle but when i fired this 80 grain seirra soft points, out of the fully factory 700 sps varmint i was getting .5 or better at 100 yards all day every day! i have never had a factory rifle do this. I was afraid to change it and ruin it. My best group today was 3/8" and also fired a 5 shot 7/16" group at 100 yards. i have also shot a 1.5" at 300 yards. for a factory rifle, factory ammo it is to hard to change anytihng unless i shoot out the barrel. I have taken it out too 500 with fantastic results from groups ranging between 2.5-3 1/4". I wish every factory rifle would do this.
I got a .5 moa shooter out too 500 yards for a total of 505 dollars! topped it off with a scope Vortex viper 6.5-20x44mm for 500 dollars and there we go. I will hopefully get to take her out further once i get a longer range.
Out of my Standard .243 Win It like H414 as well as my .243 AI.
My .243 Win is a Rem 700 VLS and it shoots 1/2" or smaller. My .243 AI is a Rechambered accurized Ruger M77MKII with a 22" bbl and It'll shoot 3/4" groups if I shoot slowly. It's a light weight bbl and will vertically string predictably up and to the right due to heat.It's just a light weight deer Rifle.
95g Bergers shoot OK out of both of them, The remington prefers 75g Sierra Hollopoints @ 3450FPS (It's my dedicated varmit Rifle) and the Ruger prefers 100g Sierra Gamekings @ 3020FPS. Hornadys shoot ok, but The Sierras have always shot the best.
The Remington has a 1-9 1/8" twist and the Ruger has a 1-9" twist. They will both stabize with good accuracy bullets up to 100g, ( I haven't tried the 105g Berger yet). I had some Old 105g Speers and they both shot those well, but alas they don't make tham anymore. I haven't tried any 105g Match bullets or 115g Berger VLDs, Didn't think that they would shoot well.