The parts:
Forward Controls Design URF V2 upper. LMT MARS compatible thick walled upper.
Proof Research PR15 barrel.
The ID of the receiver measures 0.9995” and running the calipers in or out or spinning them to any degree inside the receiver the measurement does not change.
The OD of the barrel extension measures 0.9990” consistently as well.
The clearance is 0.0005” and they slip together like butter. It’s not uncommon even with 0.0001”+ to have to thermo for a little because it won’t be perfectly consistent everywhere.
Lucky? Maybe a little. Still gonna loctite 620 it though.
Forward Controls Design URF V2 upper. LMT MARS compatible thick walled upper.
Proof Research PR15 barrel.
The ID of the receiver measures 0.9995” and running the calipers in or out or spinning them to any degree inside the receiver the measurement does not change.
The OD of the barrel extension measures 0.9990” consistently as well.
The clearance is 0.0005” and they slip together like butter. It’s not uncommon even with 0.0001”+ to have to thermo for a little because it won’t be perfectly consistent everywhere.
Lucky? Maybe a little. Still gonna loctite 620 it though.