There have been issues with those calibers. 7.62x39 has some ammo spec issue due to the varying primer depth. Wolf insets their primers significantly more than all of the other manufacturers that we've found so far. This results in light primer strikes while using Wolf. If you set the firing pin protrusion for the Wolf spec, then if you switch to some commercially loaded ammunition, the primers are softer and we have experienced primers being pierced. Although we had not changed any spec's on our end, those uppers went from being problem free (once you found good magazines) to having a large number of them returned since everyone wants the AR to act as an AK once they slap that caliber upper on. Due to this factor, we made the decision to discontinue offering that caliber.
45 ACP has been speculated on several times, the upper is pretty easy, but the magazine has always been the issue. We have played with a few different magwell conversions, but have not gotten anything that is production ready at this point. It has not made it near the top of the new products development list yet.