Not to step on UBs toes here but McMillan inlets for the certain BAT receivers. I believe they will inlet for any of them if you send the receiver to them and pay for it.
They offer inletting for the BAT 10" receivers as well.
Bruce Thom told me that McMillan does not inlet for the smaller diameter BAT receivers but they are so similiar to Rem 700s that you just have the stock inletted for a Rem 700 and leave the bolt handl notch and ejection notch off. When you inlet the BAT receiver you mill these where you need them to be. IS a pretty easy job on the ones I have done for customers.
This is the latest one I finished up this summer chambered in 338 Lapua.
This A-5 was inletted for the Rem 700 without the bolt notch or exjection port notch and I milled them in for the BAT receiver.
You also have to machine a small flat in the bottom of the inletting so the BAT will fit, again very easy.