Have you ever heard of manufacturing ramp-up? I wouldn't call it impossible. By the way, total Winchester production was 235.448 rifle (225.008 plus 10.440 rifles without bayonet) which are officially listed per End of July 1917 - this is when production ceased, not April. Anyway, it seems there are charts available of how many rifles Britishinspectors accepted. I found online sources originating from the "Record of US Deliveries" in the Ministry of Munitions Series that WRA P.14 serial 91.532 was accepted in week ending 6th January 1917. This serial is very close to the OP rifle.
Neither it is my rifle nor do I see any reason for you to write in such a manner. It seems you were running out of arguments since you do not answer any statements but prefer to personally attack. If you see yourself superior to Skennertonand his books it would be great however if you could give reasons to your statements as well.