The slight shortness in length in some PPU ammunition has been a common cause of MS feeding issues. We need to remember that back in the day, these rifles were designed around a round nose bullet (typically 160 gr) and hand tuned to feed extremely well when the COL is correct.
That's not to say you can't shoot spitzers or semi-spitzer bullets out of it. You can, but it requires a bit of "load development" at the bench. This even goes for 160 gr round nose bullets from Hornady. Their stated COL is 2.970 but in all but one of my M1900 and M1903 rifles, cartridges of that length feed and shoot from fair to poorly. Thus, I load to a COL much closer to the old Eley and Kynoch loads (as posted by Brian above) to 3.00-3.05 COL. Even then, the throats of these old rifles are deep enough that my bullets are still "off the lands". The longer cartridges are quite accurate too and the pressure remains mild. As far as factory loads, offerings from RWS tend to feed (and shoot) much better in my experience. If you are less inclined to invest in reloading for your MS, then you will likely have much better success with RWS ammunition.
but here is the cartridge length and specs for the RWS load 
