I am having a problem getting an accurate reload with the 300RUM in a Browning Stainless Stalker. The Remington 180gr Swift Scirroco did a good job, right out of the box (1 1/2" @ 100yds and 3" @ 200yds). I had several boxes of 180gr Grandslam and 180gr Trophy Bonded Bear Claw bullets, so I began loading with those bullets. Once I got up close to the MV of the Scirroco bullets (3250fps), the groups became very erratic with both the Grandslam and the Bear Claw. An "expert" at the range has told me that the stainless barrel will begin to fail within 800 rounds when firing the 300RUM. I have put 400 rounds through the Browning
First off the Swift Scirroco bullet and the trophy bonded bullets are not known for great accuracy good enough accuracy for most calibers/ranges is the best you'll probably get. Since the jacket on a Swift is copper you probably have a bunch of copper built up in your bore and that has to be removed somehow. Hoppes #9 has a great fragrance but will not cut it for removing copper fouling and is inferior to other solvents out there. Stubblejumper made a very good point about barrel life. The life is determined by rate of fire , outside temperature, cleaning frequency and method of cleaning , powder used and bullet used. You'll will witness throat erosion with this cartridge like you would with any high velocity cartridge but you have to realize that when you purchase/build the gun. You can detect erosion by using a bullet seating tool like a Stoney Point OAL gauge. In your scenario I would try a different bullet probably a Nosler Accubond, Barnes Triple Shock or something of that nature .. get it shooting the way you want and then make up some reduced handloads to practice shooting with and familiarizing yourself with your rifle. I seriously doubt your rifle is anywhere shot out..just get a good copper cleaner and go at it you'll be amazed at what comes out of that bore.