Mosin M44 Proof Mark question

[TheOldSarge]

Last week I picked up a Soviet made (1945) M44, private purchase. It's a very nice piece, numbers match except the bolt. It even has the CFO issued round sticker with a serial number still on it! Missing the cleaning rod.
I checked 7.62x54r.net for some of the marks. I found that I have a small case "y" in circle beside the Izhevsk stamp, which means it's a "Final Proof Black Powder Proof Mark".
I couldn't find what it means on that site. Does anyone know what the BP Proof Mark actually means?
Thanks.

 

[Horilka]

Picture?

 

[bp2626]

It's a common marking.

It just means that the barrel was tested to handle an overloaded charge of powder. The levels of pressure tested were higher than a typical charge of smokeless powder.

 

[TheOldSarge]

Thanks! I appreciate it. I'll know that the next time I see it. Always good to learn something new.

 

[tacfoley]

This is very useful link - http://www.mosinnagant.net/USSR/mosin_nagant_markings.asp

The Russian letter that looks like 'y' BTW, is pronounced 'oo'.

tac