B & K Slings ?

I have a National Match 1903 that has a B&K marked sling dated 1917 in very good to excellent (but used) condition. Can anyone tell me who made it, and if there is any value (say, compared to an RIA marked sling)?

Thanks

Post a photo of the sling if you can, it might help. I don't find any reference to a B&K, but there was S&K as well as S&R.

Regards,

Richard

There was also a G&K...