Hollis:

You're way off on the date. There is an I. Hollis .450/.400 for sale at Champlin Firearms with serial number 100,561. This rifle is an original nitro with 1904 rule Birmingham marks with no date code, meaning that it was proved between 1904 and 1921. Your gun would seem to be much later. I assume yours is a .500 Nitro, which wasn't introduced until roughly 1900. What do the proof marks look like? If it was proved in Birmingham, I would imagine your gun would be late enough to have the date code mark, which appears as a pair of crossed swords with a letter in the upper angle and a numeral in the lower angle. This would tell you exactly when it was proved.

To my knowledge, the I. Hollis records did not survive.

If this is an original .500 Nitro - JayZUZ! 9.75 lbs?? A British built pre-war .500 Nitro double that light would be unusual in the extreme. I have to wonder if this rifle an original Nitro. The weight would be correct for a BPE. The .400 I mentioned above is a full pound heavier. The proof marks on this piece need careful examination.
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