Bob,
It should work but it's going to be inset .45' deeper into the stock.The Huma gauge is really short at 19.0mm tall/deep X 25.14mm OD. The factory FX gauge is 30.50mm tall/deep X 25.40 OD. The hole in the stock is 26.02mm, so yes it will fit. The Huma gauge is going to need a dowdy seal to make it seal (the easiest way). The FX gauge needs a plastic bushing/washer that drops down in the hole to make it seal. The threads on the Huma aren't long enough to reach the plastic washer and you can't really rely on Teflon tape or a sealant to make it seal 100% of the time, that's been my experience with the tapes and sealants.
Personally I prefer the FX gauge over the Huma because it's a lot easier to read with a little more detail on the increments. Both gauges can be equally off as well, trust me I know..
Jimmy
