We have a 12ga BPS that was made in Japan, I do not know what all I need to ask when looking for a youth butt stock for it. If I post to buy a used one, or look up in a catalog somewhere what are all the specs I need to list or see to know if it will fit our gun? Do all years interchange... etc. I can get the ser num if needed but Don't know anything about Browning. Thanks thejanitor