'What he said' ^ , only verbose and with photos:

Here are the two types of Schönauer magazines as employed in the Mannlicher Schönauer rifles and carbines from the M1900 through the 1961, or MCA:

At left is the type used prior to the M1924/M1925, or 'High Velocity', models. At right is the type used from the M1924 through the 1961 or 'MCA' model.

Notice, along with increased 'magnum' length, the newer models have a retaining ring to hold cartridges in position with the follower (spool) at the shoulder. Notice also the area at the front (top of photo) of the previous style which is machined to close tolerances with the bullet nose of cartridges built to original specifications for models M1900, M1903 (6.5X54MS), M1905 (9X56MS), M1908 (8X56MS), M1910 (9.5X57MS). The corresponding area at the rear guides the case heads. The 'star rotor' follower of each magazine is machined to the (original spec.) cartridge profile appropriate to each model of MS from M1900 through M1910 and to the cartridge for which each 'High Velocity' rifle and carbine was chambered.

Here is the magazine from a .458 caliber M1956. Notice the presence of two rings to guide the shoulderless cartridges:

Here are cartridges in an M1903 (6.5X54) magazine - no 'ring':

The cartridges of the pre M1924 magazine were held in proper alignment with the follower (spool) by the sides of the magazine well and by the machined areas at the front and rear of the magazine body. Proper fitting cartridges will act as roller bearings in races. The more precisely they fit, the smoother the function of the magazine will be:

Notice, in the cross sectional view, the ability of a short or narrow bullet to allow the cartridge to 'tip' at the nose and become jammed in the 'void' beneath it.

This image shows more clearly the machined areas where the cartridges will 'nest' in the magazine housing (body) and be guided through the lower portion of their rotational journey. As mentioned previously each is shaped to its respective MS proprietary cartridge as is the 'spool' follower.

There seem to be widely differing accounts from owners and shooters of early (pre M1924) MS regarding the feeding habits of the Schönauer magazine with cartridges that do not closely match the profile of factory originals. My M1910 favors cartridges built to the exact dimensions of DWM531, or as close as I can get to it.

For anyone who has difficulty feeding their pre M1924 MS or has just acquired one; my recommendation would be to build five 'dummy' rounds to original specs regarding overall length and bullet profile, then cycle them. They should run smooth as glass. To run 'spires' or other shapes and sizes, find projectiles that can be seated in such a fashion as to engage the machined area at the bottom of the magazine housing.