Do you have access to the Douglas Collection? Have you physically seen this rifle? If not, on what are you basing your judgements?
This rifle has more provenance than your 300K series rifle you claim to be a WWI Marine sniper rifle. On what do you base your statement that the rifle is not a Marine rifle? Since you like to compare your rifle to others, maybe you could compare your rifle to this one, point by point, showing why you think one is a Marine rifle while the other isn't. It would be educational.
You cannot credibly judge exactly what the base in the picture is, nor can you judge when it was mounted, nor can you possibly know why it was installed. I will accept Peter Senich's judgement over your unsupported statements.
Maybe you can explain to everyone how you "fact checked" Senich's work. The reason for my questions is to "fact check" your work.
You still haven't answered the questions concerning how you know Mallory gave Senich a "packet of 100 documents". I believe everyone with an interest in this subject would be interested in your contribution.
Unsupported statements, especially those so critical of the work of others, do not further the knowledge base of the subject.
More to come.