both HV and SC stamps on BSA 1909 barrel

https://www.milsurps.com/images/impo.../2di0osm-1.jpghttps://www.milsurps.com/images/impo.../293iyjo-1.jpgI thought is was kind of different to see both the HV and SC stamps on my BSA 1909 barrel,
the rifle is a SHT L E III BSA Co 1909 serial 57521 with a top u

Markings look identical to my 1917 Enfield.

I thought it was odd but after doing some research, normal markings for the period

Some additional photos of my 1909 BSAAttachment 73692Attachment 73693Attachment 73694

Both the 1909s have been upgraded for MkVII HV ammo, the MkVII HV ammo was introduced in 1910 iirc.

Thanks for the info!