The Haenel 1900 and 1909 rifles have 5-shot, staggered double row magazines, while the Meffert "Hubertus" conversions of M88 actions feature limited capacity, single stack magazines only. Why? The Haenels are not merely "modified M88 actions". Though they look very similar above the wood, the covered, invisible is very different. Haenel receivers probably started out with a different forging to begin with, at least the machining was different, especially on the underside. Meffert had no access to the patented Haenel actions, so they had to do with standard M88 actions, unable to fit a two-row magazine to them. Here is a photo of the receiver bottoms, top M88, Haenel 1909 below.