USC to UMP Conversion Project

Required Project Components

Actual Items

• Stock, German
• Stock Axial Pin
• UMP FBI Lower
• UMP Magazine 2 each
• Compliance Parts
  • Stock Block B
  • Floor Plate and follower set 2 each
  • Trigger US

Useful: URL sites:

• HKParts a great source for parts and service. Ask for Adam.
• HKPro an interesting clearinghouse of information.
• Key Lower Housing collection of setps with photographs. This is not an exact USC-UMP match.
• USC-UMP Conversion old dogma and marketing.
• You Tube video showing the easy part of the conversion.
• Top Gun Another alternate parts source.
• HK Specialist Another parts source alternative.

UMP Magazine Cutout

Source HkPro.com Forum item. Scroll down the thread to the second post for the exact dialogue.

Your results may vary. But keep the left front centerline fixed. The back 1.540 may need to be shaved to 1.541 or a bit more. Insure the corners are rounded. This is not something you should consider doing with a hand tool. We recommend using a CNC router or machine shop with a good xy table milling machine.

Recommended Tooling

The following tools are recommended:

• Sears Probe Tools with at least two modified to approximately 6 inches or a suitable lenght to support your comfort/safety level.
• Drill press or suitable substitute plus appropriate holding fixturing.
• Drill bit 17/64 for routing the polycarbon lower hinge tab.
• Center punch 1/8. Used to pop the multiple axle pins of the lower housing.
• Roll pin punch 7/32. Used to pop the barrel roll pin
• Points file or suitable substitute.
• Small craft hammer.
• A digital camera used to quickly document how something looks just before your start to "tear-into-it".
• A CNC router or milling machine with an xy-table (or access to a vendor) for making the UMP magazine cutout.