strictly a single shot propostion there, and that goes for the 80-82 grain bullets as well. These were both designed for the 600 yard stage of National Match type shooting. This is all done slow-fire, single loading the rifle with one round at a time. As a result, the OAL was irrelevant and allowed the makers to get away with the added length in the interest of vastly improved performance.
If you want to run the rounds through the magazine in semi-auto mode, you'll need to go with something like the various 69-77 grain offereings that use a somewhat blunter (roughly a 7 caliber) ogive.
You will also have to have a 7 inch twist for those 90 gr bullets. 8 twist will work for the 77 to 80 gr (single shot). I shoot the 69 Sierra with Varget through the magazine in a 9 twist that is really accurate.