I have been shooting a custom RUM for a year now. It's 17.5 lbs, its in a B&C stock beded, Predator action, 30" Benchmark barrel with a 9.5 twist pushing a 230 Berger at 2980. I am using an extended AI mag with a cartridge col of 3.760. At a 1000yds it is just over a .5 moa rifle if I do my part. I shot a bear this year at 440 yards and put a golf ball size hole from shoulder to shoulder. It can be a meat destroyer. I have pushed this rifle to 1740yds with great accuracy. Reloading the RUM. I have 7 reloads on Nosler brass using 86.4 g of Retumo. It can be a dream to shoot but it requires a muzzle break to gain the accuracy required for longer distances. Brass can be expensive at around $2.50 each but at 7 firings they are costing me .35 cents (brass cost) this round to fire. Top this off with a good trigger and the best optic you can afford and enjoy. It will exceed your expectations.
I'm at 473 rounds out of my 300 UM and just had Benchmark look at the throat. No fire cracking yet. Their Guess is 12 to 1300 rounds depending on your load. I'm using Molly, I'm not sure that that is making any difference. But a shooting buddy has over 3k out of his 300wm. He swears it is the molly coating he uses. His is accuracy is dropping off and will be rebarreling soon.
Great think about a 300 RUM is you can use reduced loads for rock plinking and learning to shoot long range and then pump it up when you need the power. You can actually make it last as long/longer than a 300 WM that way.
lefty when you get that 300 norma I'll shoot you for your lunch money. I have no doubt my Rum will take the day. The group I posted earlier was shot with a reduced load. One node lower than this group. This isn't a one in 100 group. It is what I expect every time I uncork it.
lefty I know very little about the norma. I can only tell you that my Rum is amazing from accuracy to ease of reloading. The brass problem can be a concern. However, you can buy ammo and shoot it for practice. Just make sure you get a good brake. This makes it a pleasure to shoot.
The barrel life of a WM will far outlast a RUM. I would follow this up with a "all things being equal" but they are not equal. The RUM pushes harder and the cost is barrel life. You can extend it by letting the barrel cool between shots and using cooler loads but in general that is what the WM does compared to the RUM. If you want to push cool loads down a RUM then get a WM and you will have abundant, quality, cheap brass for life.
RUM's are NOT known for barrel life, that is why I don't drop the cash for a carbon barrel for mine. I have 3 and love them !