The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

As standard every single CMMG MK-4 rifle we sell is stripped and accurised.

Is your Upper Receiver True?
We know that these are because we set them up and lap the front face back until its perpendicular to the bore of the receiver.


As can be seen in these images, material is being removed to the right but not the left of the barrel nut extension, showing that the front face was out of alignment with the bore and therefore the barrel could not fit completely square to the receiver.



Lapping is now complete and we have a trued upper receiver with perpendicular front face. It can now be acid blacked and re assembled.

I thought you stopped selling CMMG products ?

Started again. :)

Any gunsmith will tell you the same thing, a good quality trued crown is vital to accuracy. Factory made barrels are never as good as a custom made version.
With that in mind each CMMG MK-4 we sell is automatically re crowned to maximise the rifles potential.

As you can see in the 'in progress' pictures below, the crown was indeed not perpendicular to the bore. After we have finished work the rifle has a nice clean trued crown and will shoot better for it.