Shimming to change the comb is tricky business. Recommend you contact the Browning Service center for advise. Use the link below for your convenience.
Contact Browning.
Your Browning model citori B525 over under shotgun was made in 2 models,the sporting and the golden clays.Both were made in 5 grades,from Grade 1 to grade 5 with ascending levels of embellishment.The golden clays has a oiled finished grade V stock with solid pad and schnabel forearm.engraving pattern that depicts the transition of a game bird to a clay bird in 24K gold.This model includes 5 midas grade Invector choke tubes.the sporting grade.
Try Midwest Gun Works.
You will need professional assistance from a stock maker.
Best left to a gunsmith
stock is standard american walnut, no stain.
Best left to a gunsmith with the proper tools.
Impossible to answer on the internet without detailed pictures.
Must be examined to be sure.
I would like to start out with I have never seen a Browning serial number as described by you.Are we sure that you have a Browning 16ga shotgun,or another made shotgun that may have used Browning,s patent?I must admit that I have never seen a straight stocked Browning shotgun or heard of one in my many years of collecting firearms.
Try Mid West Gun Works
according to Browning Service and a local gunsmith - YES