P.-'14 and M-1917 (basicaly the same rifle, just different calibres) were built in three factories (apart from the super-arly .276 model bult at Enfield. These are:
Winchester Repeating Arms: rifles marked WRA or W
Remington Arms at Ilion: RIA, R
Eddystone, Pennsylvania: ERA, E, the ERA standing for Eddystone Remington Arsenal.
As far as ejector springs are concered, these are a splinter off the side of the ejector itself. There are none avalable anywhere unless you have too much money. You can do a repair by yourself by removing the ejcto from the ejector box/bolt stop of the rifle, cleaning everything up very well and then epoxying about a third of the spring from a retractable ballpoint pen (available free from your local bank if they aren't watching) to the left (outer) side of the ejector. This spring then will bear directly against the ejector box and thrust the ejector blade against the bolt as the bolt is withdrawn. Result: ejection. I have 2 rifles here that I did this repair on 33 years ago and they are still working fine. Cost? A whole penny's worh of Acra-Glas and an hour of my very valuable time.
Hope this helps.
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