tr63,

Do you really need a 3" piece from an "early" receiver or will a piece from any MK 1 work? On the pictures I've seen of the DD brens the rear 3 '' of the receiver appear to be identical to all of the Mk1's.

Military Gun Supply has demilled MK 1 receivers for $70.

If you haven't already checked, guys from this forum may be able to come up with some pieces:

Login (weaponsguild.com)

BAR is definitely right if they are not from the same gun they will take more work and fitting but what you are adding has no markings so you can grind away.

Good Luck,

Joe