This MDT .300 WM magazine can be used for 7mm mag, 30-06 and 6.5x55 calibers. In some cases the feed lips may need to be bent. Maximum cartridge OAL that will fit is 3.625".
Assume this will be compatible with any .300 WM, AICS equipped rifle, such as my Begara Premier Ridgeback in .300 WM?
Yes that is correct.
Will 270 caliber fit this magazine
No i believe you would want a 30-06 aics magazine and then need to bend in the feed lips for the magazine to hold the rounds in place.
Are these magazines compatible with the 300 prc
No sir, you'll need this magazine https://mdttac.com/300prc-mdt-metal-aics-magazine/
Will these work with factory loads. 28 nosler 162 gr hornady precision hunter.
I believer you will want this magazine in .338 LM with 3.850" length. https://mdttac.com/us_en/mdt-metal-magazines-long-action.html. I would double check and ask MDT themselves about your .28 nosler just to be sure.
Great product, glad I went with Grayboe!