.223 throats and magazine Q

I have a 1993 production 110 chambered in .223 with a blind magazine. It seems to me, with my rudimentary chamber measurement with a bullet fit in an unprimed case, that the throats is longer than what can be loaded for and keeping within magazine length. Is this common?

I also took the action out of the stock. The spacer at the rear of the magazine is metal that is dog eared into the box, and the box is peaned into the bottom of the action. Is there a work around to get a longer OAL without single loading and doing a bunch of metal fab work? How well would the factory follower work if I did remove the spacer, trimmed it, and reinstalled it about .2-.4" further rearward after drilling the sides of the box for the tabs? Anybody done this?