gyvel: Am I to understand that the slotted Browning Hi-Powers that were sold in the not too distant past as "Capitan" models when coupled with correct FN board stocks are, in fact, NOT legal per BATFE?
If they aren't on the ATF Curio & Relic List or the firearm does not have a tax stamp for an SBR it is not legal.
The actual "Capitan" models (not all tangent sighted HP's are Capitans) imported by Browning and marked "Made in Belgium, Assembled in Portugal" did not have a stock slot. Most "T" & "C" series (mid '60's - mid '70's) also did not have a stock slot cut on their tangent sighted models.
The tangent sighted FN Hi Powers w/ slot imported by Vector Arms w/ "Browning S.A." on the right side of the slide would not be legal without a SBR tax stamp. These are often seen with a large black, FN box instead of the small gray, Browning box.
PTK:...Seriously, though - the description of "IN" the stock, it's a holster stock. It's the correct stock for the gun.
Again you are giving advice on a stock you have not seen. By "IN" the stock you mean the stock itself is the holster- that would be the Inglis stock. That is not an Inglis HP. "Flatboard" stocks for this period featured a leather holster riveted to the exterior of the stock. Again, your advice is dangerous.
Until the OP puts up a photo of the stock and additional pictures of the HP we won't know if he is in violation.