Boyd's leaves a bit of clearance around most of the receiver inlets in their stocks.
In some cases, it's not necessary to glass bed the receivers, but in most stocks, it's advisable, no matter which manufacturer you get it from.
Some custom stock makers take pride in how close the tolerances are to an individual receiver.
There just isn't any way for any manufacturer to "perfectly fit" every stock for every receiver.
Most of them come very close.
I've used Robinson (now deceased), Stocky's, Boyd's, Robertson's, Bishop, and a few now defunct makers.
Unless they had the barreled receiver in their hands, perfect fit was not guaranteed.
So, they cut the inlets a bit large, or if it's a small one at a time custom maker, they will mill the inlet slightly small, so a smith or recipient can finish to their satisfaction.
If I were ordering a stock from any of the people I've used in the past, I would expect to have to glass bed the receiver to the stock, which would eliminate the OP's issues.