Big Boston locked out

I was looking through my 1897 parts drawer and noticed a shorter follower without the two raised witness rings and it was a bit shorter than the original 1897 follower. I installed it and could feed six into the magazine. It functioned normally. Investigation indicated it was a Model 12 follower. However, other than your post, I've not been able to find any mention of the 12/97 follower swap. BB