I have seen maybe 3 pre "McDermott brand" cues.
Authentication can be difficult with them, he died in 2014. Jim McDemott was repairing and making cues since the mid sixties out of his home. The McDermott brand we know today started in 1975 formally.
Any provenance could help. Letters stating origin, ownership transfer, etc.
I don't even know if any of the McDermott family can really authenticate the early ones.
There is nothing about it that makes me immediately reject the notion that it is a McDermott. As far as I know he used various joints, butt caps, bumpers, etc before settling on the now classic McDermott design.
The joint pin, collar, ring, and pilot look very much like an import though. But that does not mean that is what this is for sure. I am suspicious that it might be though.
The butt sleeve looks a lot like n MR-5, which this cue is not, but there is a strong design resemblance.
McDermott did later used similar maple dashed rings. But they were centered in the black ring, not offset. That exact ring with that exact offset and that exact pilot is seen in a number of imports. And that pin as well. Including, I believe, Adam cues.
The pilot is unclear to me, if it is just exposed tarnished brass then it is more like an import. If that is a dirty wood pilot, then more like US. If compression fit, then very likely custom US made.
I think I have pics of three early McDermott cues on my hard drive. I have no idea of the veracity of the claim that they are by Jim except I did know one of the owners that was a neighbor of McDermott who was there when the cue was purchased. Actually two were purchased and the other was sold long ago. It looks a lot like an early 70's Viking, it appears to be a WICO blank, so you have to believe the story...Plus it has a window with "Cue by McDermott" in it.
This cue is intriguing for me. I do wonder what can be established as far as the origin.