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Mountain Arms
Providing custom upper receivers and machining.
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300 WSM custom uppers.
Designed to fit on a standard DPMS lower receiver (No lower receiver modifications necessary).
Upper receiver currently comes with optional 12" carbon fiber, 12" aluminum, or 15" aluminum
 Custom 300 Winchester Short Magnum U |  Custom 300 Winchester Short Magnum U |  Custom 300 Winchester Short Magnum U |
|---|---|---|
 Custom 300 Winchester Short Magnum UThis is a truly custom upper built by hand by an expert armorer. It has been test fired for function. The upper was tested with several different brands of ammo. Bullet grain weights varied from 150gr to 190 gr. Specs: •24” Lite Barrel •15” Free Float Handguard •Adjustable, Lockable Gas Block •Bolt, Carrier and Charging Handel Included •MPI Tested Bolt •Bolt is Melonite Coated |  Custom 300 Winchester Short Magnum UThis is a truly custom upper built by hand by an expert armorer. It has been test fired for function. The upper was tested with several different brands of ammo. Bullet grain weights varied from 150gr to 190 gr. Specs: •24” Lite Barrel •15” Free Float Handguard •Adjustable, Lockable Gas Block •Bolt, Carrier and Charging Handel Included •MPI Tested Bolt •Bolt is Melonite Coated |  Custom 300 Winchester Short Magnum UThis is a truly custom upper built by hand by an expert armorer. It has been test fired for function. The upper was tested with several different brands of ammo. Bullet grain weights varied from 150gr to 190 gr. Specs: •24” Lite Barrel •15” Free Float Handguard •Adjustable, Lockable Gas Block •Bolt, Carrier and Charging Handel Included •MPI Tested Bolt •Bolt is Melonite Coated |
 Custom 300 Winchester Short Magnum U |  Custom 300 Winchester Short Magnum U |
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