go for better. for sure they are good groups, especially as you are doing 15 shots unlike the 3 (useless) or 5 (slightly better, but still not representative) most people shoot... but do try a few more.
Had similar groups but only at 22 yards the other day in a rapid I'd finished machining the barrel for... then tried QYS 8.5s much better, but some vertical stringing.. checked on the chrono and they gave more energy, but more variable.. weighed a few and realised the weight consistency wasn't great. If I could be arsed I would have sorted them into weight batches. you seem to have the same vert stringing and also using QYS, so do check the weight consistency. Then I tried JSB heavy... oh yeah baby, looked like a single .25 pellet, about 2mm c-c
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.