After looking high and low for a 1/2" barb fitting that didn't choke down to 3/8", I finally had one made:
Side X side with a standard 1/2" hose barb:
Comparison of bore diamters:
1/2" full bore hose barb
Side X side with a standard 1/2" hose barb:
Comparison of bore diamters:
1/2" full bore hose barb