I don't believe that the LAAW tube would withstand the pressures of a 60mm mortar round being fired. Maybe Charge 0. (only the primer, no powder bags). Also, the LAAW was 66mm, so there would be a lot of blow-bay.
In Vietnam we broke the tubes to prevent the NVA/VC from hanging them over a trail. They would put the cotter pin back in to hold the flip-down door closed, then slide in several frags with the pins pulled. The spoon was held by the inside of the LAAW tube.
A monofilament fishing line was tied to the cotter pin, then strung across the trail just above head height. That way it would snag the folded up whip antenna on the radioman. The radioman was often with the officer, forward observer or forward air controller and in the center of the patrol.
They would screw the firing assembly out of the frags and break off the delay element, then replace it. This would cause the frags to detonate immediately after the spoon flew away, right about head height of the patrol coming down the trail.
We made sure that we smashed the LAAW tubes.
Thanks. The mortar thing must have been a miscommunication or a faulty memory on my part. I even taught the LAW block of instruction a few times and I always thought the idea of using them as mortar tubes seemed far fetched. I was in the Army in the 90’s and at that point I guess we knew we were supposed to break the tubes but had forgotten why.