Who has successfully removed the mag box spacer in a 223?

[TXNative]

I need another .100" to seat 75gr AMax's to the lands.

Second, 69gr SMK's when seated to the lands fit the mag box but they will not feed, they hit the barrel below the bore by a 1/16" or more.

How do I address this other than seating the bullets deeper?

This is the project, a Stevens I bought a year ago and dropped a 3/8" steel fuel line in the center channel of the tupperware stock and filled it full with Devcon, installed an EGW base and Savage big bolt handle. I plan on switching the handle to a Tactical Works handle but I will leave the Conquest on it for the long haul. I don't like the bulky picatinny rings and they are too high so I will change those out too. It shoots pretty dang good as is but I am still playing with different loads.

My youngest daughter smacked her first whitetail doe with it last year using the 69gr SMK and claimed the gun. She does not know but she has a Savage 11 243 on layaway and my oldest has a Stevens 200 243 on the way, both will get rigged up for Christmas this year. I banked on 85gr TSX's and bought 600 for the girls rifles and a 6mm Remington problem child that happens to like the TSX.