I just shot a .22lr match yesterday at one of the local club/ranges and it was one of the first that I've shot in several years since the Vintage rules have a restriction on ammo price and with the current shortage, low priced 'match' ammo has been non-existent...
Over the years, I have found that Match Rules can vary in both extremes when specific questions are asked...Usually there is Stock class, Modified Stock Class, and Open Class at the least...
This is where the nitty gritty comes in on questions...Factory Stock is usually just that, with the allowance for an optic (and that may be specified as to maximum power).. Modified Stock involves minor enhancements, such as triggers and a change to open sights to peeps, etc...Open is usually "anything goes"...You really need to check the specifics before you get too involved in new acquisitions if you are serious about competing...
While the match yesterday was pretty much open (there were some beautiful customs), I shot my Factory Stock 1937 Walther Sportmodel-V with an old Tasco 8-32x optic and fortunately I had sufficient ammo, matched to the rifle, available to complete the match...I did learn that the barrel much prefers to be 'fouled', rather than clean, as my first sheet of 5 targets was a measly 228-7x of a possible 250 (with a pristine barrel) and my third sheet was a 248-14x of a possible 250 after the barrel got sufficiently fouled...