... to solve for me.
What the heck are these strange collars and why did I find them on these three 6900-series magazines I found? 
The gun shop guy said they must be space fillers for using 6900-series magazines in a shorter gripped gun... but there are no shorter gripped 3rd Gens that could use such a thing.
Help!
Anybody run into these before? 
p.s., Yes, I bought the mags anyway.


The gun shop guy said they must be space fillers for using 6900-series magazines in a shorter gripped gun... but there are no shorter gripped 3rd Gens that could use such a thing.



p.s., Yes, I bought the mags anyway.
