I have an Underwood carbine. Did Underwood ever make a marked sling. My carbine is late war. I do have 2 slings Both are OD green. One has the C clips and it is marked IBM. Definitely original, shows age and wear. Plus correct catches. The other is OD canvas with the larger parkerized metal ends. It is marked MRT. It also has a few; hate to say it blood stains on it. Is this a correct sling for my carbine?