CB-4100-12B Wads

[Hixie]

I am looking for a light recoil load for a sleeved Parker GH 12 gauge gun that won't put too much stress on the stock head and wrist area. I wanted to try loading some 7/8 oz loads according to the following Hodgdon recipe: Rem STS hulls, 19.8 gr Clays, CB-4100-12 wads, Win 209 primers, 6100 psi, 1250 fps. My PW "M" powder bushing throws 19.5 +/- 0.1 gr of Clays and the 7/8 oz shot bushing throws a hair less than 7/8 oz.

I already had the hulls, powder, and primers so I ordered the wads but was sent CB-4100-12B wads. I couldn't find a good explanation on what the difference between these two wads might be but I did not see any red flags. I was wondering if anyone on here has an opinion as to whether this is a safe substitution or not.