I had a XP-100 in 350 RM, that I loaded 250's for. Didn't have a magazine issue but I did notice that after a day of black bear hunting that I had to pull my bolt out in order to get a loaded round out of the gun! Never expeienced that at the range because I never ejected a loaded round.
Back then I used Rem PSP bullets (discontinued) but now I use Barnes (discontinued), Nosler Part and Hornady RN in my 358 Norma. I picked up 300 Norma 250 and 280gr bullets at an estate sale a few years back. I look forward to using the 280 gr bullets in a 358 WSM that I just had built.
In a model 7, I would stick with the RN - they are a little shorter.