Originally Posted by
Hotolds442
It looks to be in about the same location that the bolt handle on my 243AI resides when the 243 Winchester go gauge (243AI no-go) is installed. The center of my bolt handle locates just below the bottom of the serial number.
Since it's an AI chamber, the biggest determination is whether factory 223 ammunition will chamber. Since factory brass needs to be a crush fit before fireforming, you have to have the ability to close the bolt handle fully while still providing that .003"-.004" crush. Tighten the headspace up a bit from where you are now and you may not be able to chamber "all" factory 223 brass. Using once fired brass may be even worse.
I'd tighten it down there, and fireform a few rounds. Full length resize the fired rounds in the 223 AI dies with the sizer screwed all the way down on the shellholder, and then see if they chamber. If they do, add tape to the cartridge base until the bolt handle won't close, and then measure the tape thickness. That will give you a real good idea of where you're at and where you need to be.