It is interesting to see that you are not only succesfully recreating a classic handgun, but are also subjected to exactly the same problems that the original Parabellum producers faced.
The sheet metal 08 magazines were always an issue in the past. Most problems were solved by the milled / welded Haenel magazines in the 1930s.
You may want to look into reproducing a Haenel magazine in .45 ACP. It may solve a lot of problems and ease production.
Also what killed the Parabellum in the old days were the manufacturing costs, Mauser had optimized it's production pretty well in the 1970s but still struggled to make a profit. Krieghoff's attempt in 2009 cost about 13,000 Euros per gun … So you are not doing that bad
