LRF,
reread my post. My Gibbs M-Sch m1903 is dated open on the receiver wall “Steyr 1905”. I guess Gibbs would have scrubbed off a receiver date if he had built a “new gun” on a receiver already several years old. As I wrote, that Westley – Richards ad is from their 1912 catalog. The drawing is from Schmidt & Habermann’s 1880 patent.
As I have that Zielvier scope mounted on the receiver, I have blocked the hand take down feature on my rifle in the Interest of accuracy. So I will not take it apart, if not absolutely necessary. Instead, here is a photo of a takedown Gibbs Mannlicher I once stole from this NE forum. Here you can see the full threaded barrel and the backed out front guard screw. His screw goes into a shallow hole or dimple in the barrel threads when the rifle is assembled. IMHO the weakest spot of Gibbs’ system as the screw cannot clamp the action to the stock wood and the barrel in the receiver ring at the same time. With a bit of wear or wood shrinking or swelling one of it’s functions will become loose, as it did on mine.