Hi Pat..The pump should be free to turn by hand after lapping in...and should stay like that in storage for a long period of time. It is common though, when it is refitted to the crankcases, for the pressure of the locating bolts to exert a degree of 'pinch' on the pump body, making it tight again.
BSA manuals advise not to overtighten the pump retaining bolts but that is purely subjective as the bikes pre dated torque wrenches and no settings are given.
Of course there is a natural tendency to give them an extra tweak..nobody wants to risk the possibility of the oil pump dropping off!
After fitting cam spindles, bearings etc. to the timing side case, and before the cases are put together, the next thing I fit is the oilpump and drive spindle.
This allows you to access the top of the oilpump drive spindle with your fingers to check that the pump is still free to turn.
If it is not, more lapping will be required until the pump frees off when fitted.
If the pump has gone tight in storage that would be unusual..but the solution is the same.
Check individually that all the pump gear spindles are free to rotate in the end plate and body prior to assembling the pump and then lap the gears into the body as required.
The process removes raised parts of the mazac casting which expands when it corrodes..so you are basically returning the pump to its original clearance dimensions or close to that..rather than lapping more and more of it away.
I have never had a BSA pump yet that does not pump adequately after completion of the work...Ian
email (option): ian@wright52.plus.com