Question (maybe stupid) about piston ring diameter

Hello everybody, recently i bought a set of piston rings from cb750supply.com for a 1976 cb750 f, as far as i knew the engine was fully stock, so i bought the standard size ones, when i got them i tried them on and the diameter was ok because they fitted perfectly BUT they weren't thick enough, it was a little space between the ring and the edge of the "canal" where the ring fits. So after seeing this issue i returned them with one of the old rings i had (which was thicker and fitted well), they received it and told me that my old ring was similar to the oversize ring (61.25 and 61.50), so they told me to measure my pistons to see which size i need it.
SO, my question is, is it possible that my pistons are oversize? because as i stated before, the rings they sent me fitted perfectly in diameter just weren't thick enough. I assume i would have another problem if i ask for the ones with the 61.25 specification or 61.50, because i assume the diameter of those ring would be bigger than my pistons. Or can somebody tell me if they could work?.. i cannot go and measure them because for the moment i'm out of town.
Just to be clear, the guys from cb750supply have been great with this situation and have responded all my emails throughout the process, but that question that i have is the only one that i havemt had an answer about.
Hope somebody can help me and i hope i was clear english is not my first language.
have a great night.

so the rings were too thin in vertical cross section ?
as far as them being correct diameter, end gap is the clue or teller so to speak

yes, the problem was in the vertical section, so they recomended me to buy the oversize ones, but i dont know if this is reasonable when i had the correct diameter.

huh well that is a problem,oversize rings of the same mfg brand will not be thicker
sounds like you are sourcing rings from a different piston mfg than the pistons you have now ?

uhm, i got lost at mfg, whats mfg? and there could be a possibility that the engine got different pistons and the last owner didnt know or forgot to tell me that detail

mfg= manufacturer

Most OS pistons will be stamped as so on the piston crown. Are there any markings on the piston?

+1 that or just measure your bore size

i'll get a refund, later ill post a picture of the pistons hoping sombody can help me out.

i tried the ring on the bore cam and it fitted perfectly also

what is the measurement of the bore ? get some digital calipers and learn to use them

it a 61 mm solid for me, as i stated before de rings, when speaking about the diameter, fitted perfectly when introduced on the bore cam and when tried on the pistons that why i think my pistons are not oversize, the oils scraper ring just wasnt thick enough to fill the space where it goes, the compression rings were perfect.. I just want to know if somebody has had this problem. I would aprecciate if somebody could tell me where to buy the ring due to experiences. Thanks again.