there is the
110 long action in small shank
110 long action in large shank

and then the less common 110 long action closed top like i have on my 110 FCP HS Precision in 300 PRC. I can tell you there is a noticeable difference in this receiver over the open top large shank receiver. The closed top one like i got here is night and day smoother than the standard one. Much tighter tolerances. Super smooth bolt. Best out of the box savage action i've ever handled. I could be wrong but i think its the target action just milled out for a magazine. Anyway, here is a photo of mine if you never seen/noticed one.