Adding M-50 Magazine (Short) Extension by n0mad.

Rifles/Madsen_M-50-Magazine_Extension_Short-n0mad/README.MD

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+# N0mad's madsen m50 short magazine extension
+
+#### Author
+n0mad
+
+#### Version
+8.0
+
+#### License
+Copyright 2018 distributed under the GNU General Public License v3.0 (GPLv3). 
+
+#### Release Date
+2018/09/18
+
+#### Description
+This is a two part magazine extension for madsen m50 magazines.
+
+#### Test Record
+This was tested on with a madsen m50 submachine gun.  As of version 8 it feeds and runs when loaded up to 40 rounds (+8 rounds).
+
+#### Printing
+* All printed parts were printed out of PETG, with an infill of 25%. Abs should also work.
+* No support material needed.
+* Print both pieces on their back to prevent the use of supports.
+
+#### Finishing
+* Aquire four bolts of the appropriate diameter and length. I used chicago screws and bolts for a cleaner finish. 
+* Drill out holes to fit bolt size. 
+* Existing factory springs will work.
+* Clamp around magazine bolt down, no floor plate needed.  
+
+#### DISCLAIMER
+Use this information at your own risk and responsibility.