Well this went a different direction then expected.
Ty for your opinion.
My issues and our debate is looking at a 300 Norma and then a 300 Run the Rum has a lot more case capacity but yet a lot of ppl are shooting really the same MV as ppl with the 300 Norma, and we were looking at pushing the big grain pills as fast and as accurate as we could in a 28" barrel but just looking around a couple forums at the loads ppl have shared it seems you get lil to no increase with the extra capacity that the RUM offers over the Norma. If we can't push the lead faster with the extra capacity then the 300 norm seems to be a better pick! Understand the drop in returns but it seems steep.
Now I am wondering if you say both loaded in ADG brass and can handle the more psi better if u can start seeing more return on investment of powder
The problem with a 300 norma is the low shoulder angle. It causes a lot of brass growth in the neck length. Thats why a lot of guys run an improved version in the 30-35° range. Some say a 40° causes shoulder bump issues but I have not observers that in a 280ai nor the 7max. I have a 300nmi with 33° shoulder and it works well. Capacity only grows 2gr but it helps tremendously with growth and gives a slight bump in speed. Lapua brass is awesome, and that's all I'd recommend in that chamber. I've read the adg 300nm is just as good but I have a bunch of lapua. The rum is such a long case, you have to push bullets in a long ways to have a repeater even with a 4" mag box. You're on the right track with the norma, case heads last forever 100 pieces will likely last your barrel life perhaps two. I've ran 215 Bergers to over 3350 fps and primer pocket was still like new.
@elkaholic I wasn't trying to chastise you nor your case designs even though it may have appeared so. Everyone looks and talks about like they're magic. They do perform very well for that they are. But the pressure is high to get the affects. Much more than the parent case was designed for. If a person is to run one I highly suggest a quality custom action, and the best brass available.
300 rum will go fast but is hard on barrels. 300 norma is slightly better life. If you're after barrel life, a 300sm may be the answer but nobody has had one long enough to burn one out so jury isn't in. Powder choice has a lot to do with it. N570 is very hot and will eat throats in any case using it loaded to the top end of pressure curve. Retumbo and H1000 are better for this but don't give the same velocities. RL33 will give great speed but reports are temp sensitivity and LOTS os carbon unless loaded to high pressures close to lands.
The beauty is the 300 norma is the short 2.48" Case, you can throat it accordingly and still mag feed almost any bullet but a 250 atip seated above donut area. Bearing surface is extremely long on that slug.
There are several great smith's that have their own version of the 300nm improved, Alex Wheeler has a great design and his skills are impeccable. He also has dies on hand usually for his chambers. Dallas Lane does great work, as does Ryan Pierce. These high end smith's make great products, but they're not cheap, but quality rarely is.
I don't know everything and never will. Having a dozen custom rifles, everything from 338 edge, 338 rum, 300 rum, 300nmi, 30 nosler, all using best available brass, the heaviest bullets appropriate to case capacity, and the best powders for speed and 26-28" barrels, I've been around this block a bit. I feel the 300nm improved variants are the best balance to keep performance, some barrel life, best available components, all in safe pressure levels. It can be configured as a repeater from bdl, or run aics cip mags. The only hang up is the Rigby parent bolt face. More and more options become available all the time luckily. Defiance, Bat, or terminus as your best choice for these. Mine is on a kelbly which has served me well, but I don't care the the silly bolt release nor the standard rem 700 tenon diameter. I suggest the larger tennon with a 1.25" shank barrel. It adds a slight amount of weight but gives more strength. It's not absolutely necessary but a good idea.
These are just my observations from experience, take them with a grain of salt as my opinions are my own. Good luck with your build, as long as you make it what YOU want, you'll be very happy with it.
