Originally Posted By: PALUNC

On the barrel flats,
729, a crown over letters BNP, 12 inside a turned square,
2 1/2", 3 tons per squire inch.


Your guesstimate of the date was way wrong. These are standard Birmingham marks for the 1954 rules of proof (executive date 2/1/55). Crown over BNP is the new Birmingham definitive proof mark; .729", 12 in a diamond, 2 1/2", and 3 tons per (square)" are bore, chamber, chamber length and service pressure.

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Just ahead of the flats is what appears to be an H with a crown over it.


It's a crown over the interlaced letters BP. Birmingham provisional proof. Indicates that these barrels originated in Birmingham.

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Also on one side is a X with the letters P/I with a crown on oppisite side of the X.


It isn't an X, it's a pair of crossed swords. This is the date code. The letter "P" will be in the 9 o'clock angle, the "1" in the 6 o'clock angle (identity of the proof inspector conducting proof). What you're having trouble with is in the 3 o'clock angle. Can't be a crown. I think it has to be letter "B", since there's no other letter that can accompany letter P that was used with this style of date code. "PB" is the date code for 1964.

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Now on the reciever it is stamped BNP, it also has a slash with a crown on top.


Yeah, the definitive proof mark was stamped there since the inspector's view mark previously placed there was eliminated under the 1954 rules. You didn't mention London's view mark (Crown over "V") from the original London proof that would be stamped on either side of the water table. They should be there, along with Birmingham's definitive proof mark.

The Crown over "R" reproof mark is not used when new barrels are proved on a previously proven gun. Since it seems to be absent, the barrels are definitely a replacement.

"Serious rifles have two barrels, everything else just burns gunpowder."