It's strange you should ask if Remingtons brass is soft. I can tell it's soft in my Ultra, but really it's not too bad, it could be worse.
Example;
I was at the range yesterday and a guy I know that works at a local gunshop was shooting his 300 SAUM. You should have seen the cases that were coming out of that thing!!
The case head had ejector marks on every one of them. On a scale of 1-10 the marks were about 3-5, with 1 being ever so slightly noticable and 10 would be brass is extruded to the point that the stamping is no longer even visable under the ejector mark.
What was amazing to me, as I've not ever seen brass do this before but, brass actually flowed out into the "extractor" groove right next to the ejector button in the rmainder of the unfilled extractor slot. When ejected, it tore part of this extruded edge off, but plenty remained mashed out past the original case head diameter. In my opinion, these cases were basically trashed now.
This was Remington factory ammo loaded with the new bonded core 150gr Core Lockt Ultra!
He fired them over my Oehler M43 to see if MV was possible way high, indicating high pressure.
MV were:
3020
3031
2976
3066
2974
2992
ES = 92
AVE= 3010
Believe it or not, this load grouped under 2.5" at 300 yards every "5" shot group. He fired them fast too. The rifle was one of the new Remingtons with the camo stocks, with a light weight SS bbl, not sure what length, 24" I think.
...
My friend Charlie has a 338 Ultra and he's used three different lots of brass and they all show ejector marks and stiff bolt lift with medium loads, and he can't get published MV's with it either. I would have to guess both of these guys has brass that is SOFT, as MV's were lower than expected on both rifles with factory loads, and only medium charge weights with the other rifle.
I think my 300 Ultra brass may be a bit better than what's mentioned above, thankfully. It may be all the 300 Ultra stuff is better. My dad is wanting to have his 30 cal AR-30 chambered in 300/338 Ultra, as the 338 Ultra brass is just short enough to fit in the magazine where as the 300 Ultra brass is too long at the shoulder. He don't want to anneal, so he doesn't want to pay for 338 Lapua brass and not get the life out of it, and grinding a 300 Ultra FL bushing die shorter would be an easy and inexpensive solution.