Attachment 121085Attachment 121085Attachment 121086Attachment 121087Thanks Marine! You have been very helpful. It is a great relief getting help. Here's the latest dope:
1) Note where your handguard band is relative to the bas port hole. Mine rests at the barrel/receiver joint about 3/8" further away...which is contrary to our theory that the barrel has been turned at the chamber end;
2) Inspecting the handguard band it is marked with a royal crown. Is the diameter of the receiver in that area of the P-14 slightly smaller than the M1917? Ive ordered an M1917 handguard band as well as a bayo band (the cross bolt hole was bunged up), so that should place the handguards back about 3/8".
3) The lower handguard has a "W" stamp inside but the sight groove is 2.5" long (Remington length) and the upper end does not look shortened, but there are some strange marks. The upper handguard does not look to be shortened either...to my eyes. How long are your handguards between bands?
4) The result after replacing the handguard band that sits back where it should is that the handguards end up 3/8" short of the end of the stock. The stock measures 42 1/4" long. The stock is clearly a new production. There is no grease or oil marks and no stain or finish on the wood under the lower band. If I take a chance and shorten the stock myself...problem solved...right!?!? Y E S, but the rifle and stock will be SHORT! It ight not be noticeable, but I ILL KNOW. Im a Germanicon-American Mechanical Design Engineer (or I was) and I would have to really work hard to forget. But at least the bayonet ill fit!
5) NOW...the barrel itself, per your theory, the barrel may have in fact been turned down. However Ive checked headspace and the bolt ONLY closes on "GO". The throat and muzzle both measure below 2. If turned down it is a remarkable job well done. Additionally, there are no marks in the barrel indicating it has ever been removed and reinstalled. And finally, it is fully Britishicon proofed (possibly in the RA plant), rated at 250 tons per I (I think it read "Inch" before the machining). There is a flaming bomb cartouche that would indicate US acceptance. The barrel profile also seems different from the few pics Ive seen of another M1917 barrel.

Conclusion: Ive no friggin' idea! The handguard locations is set by where the handguard ring butts up against the swell on the receiver. The barrel is not a factor in that regard. I have to think/hope the handguard ring is incorrect, or a P-14 ring, and the new ring will fit correctly and the handguards will set back 3/8". However, the end of the handguards will then be 3/8" short of the end of the stock. If I had the skill and nerve I could probably get an unaltered lower handguard, shorten my upper handguard and create a new bayo band inlet and shorten the very end of the stock the requisite 3/8" which then aligns everything...and the bayo will then FIT! HOWEVER, my stock is ALREADY 3/8" shorter than yours, so WTF! If the lower handguard were shortened then the explanation has to be that the barrel was shortened AND, coincidentally, a wrong handguard that was installed that would not over the receiver and locate in the correct position, which THEN forced the modification of the upper end of the lower handguard! This almost sounds contrived, but it explains everything and I am very doubtful that the stock length is larger then spec.

So, after all that Sherlock Holmsian sleuthing, what do you think? A quick check can be a comparison to determine if my lower handguard has been shortened. My lower handguard measures approx 9 5/8" between handguard and upper band edges, and my upper handguard measures the same between the lower band and bayo band edges. Also, my barrel is 25 1/8" from the shoulder to the end of the muzzle. Can you provide any measurements from your own rifle for comparison? Your help is greatly appreciated.