Oh dang, I can't say mine are the "most accurate." I've just made some incredible shots with them, iron sights and scoped.
As far as why mine do so well, 6 are tuned by John Thomas & only other one is a FWB300S. From L-t-R: HW30 .177/JSB 8.44 4.51, RWS 34 .22 TO6/5.52, R1 .22/5.53, HW77K SE .22/H&N FTT 5.53 14.66, RWS 48 .177 JSB 10.3-13.43 Crosman 10.5's, & RWS 52 .25 TO1 H&N FTT 20.14, GTO 16.54, and JSB 25.43. H&N group best.
Bottom is my Lefty FWB300S .177 & AZ Rapid .22. FWB eats just about anything but I like the 8.44 JSB 4.51mm.
3 springers are scoped, 4 aren't. I have more than enough scopes but since I still can use the irons, I plan on enjoying them until my eyes fail me for plinking and hunting. Real groups beyond 10 yards must be shot with a scope. I don't think human eyes can match what a scope can do. I do want to scope the newest 34. Super nice shot cycle and middle of road between my HW30 & R1 weight wise.
Tuning is a important thing but I'm not the one to speak on it in any technical sense other than a good proper fit of everything that needs it makes the shot cycle much more enjoyable, tightens inconsistencies which would otherwise show up on paper. Of course a good predictable trigger that stays set as desired is key to precision shooting. Tuning encompasses all of these things and more. Knowing what thread locker, anti seize, to use, or not use is extremely important.
I forget what it's called Edit: "Duh, Vibratitr" but there's a great substance that deadens most all vibration & backing out, doesn't set, is reusable although if it gets anywhere around aluminum it reacts & corrodes seals. Weird but falls into OP question of tips & tricks.
This was my John Thomas tuned TO1 52 .25 with a H&N FTT 20.14 @ 700fps.
Iron sights, as shown at end of video. Rabbit at 52 yards. Not "Graphic" up close but definitely DRT hit in head.
https://www.airgunnation.com/topic/who-says-springers-arent-capable-iron-sight-head-shot-52yrds/ Edit: Same 52 .25 allowed me to whack English Sparrow at 83 yards & iron sights a few months ago. 78yr old Dad witnessed it but I didn't think I would even get that so didn't film. I don't post on YouTube or anything.
I don't have much of a problem holding a sub 1/2" 5 shot group at 75. I guess I'm going to have to try it at 100 & post back later. It's my first choice for impressive springer long range groups. At 30-50 I might pick a .177 or .22. At 10-30 definitely pick my FWB300S.
Edit: And one last important thing I would like to state out of respect for all the people that tune springers. There's lots of very good tuners. Mike Ellis, Scott Blair, Bill Zizzy, Motorhead Scott Schneider, etc who do know the secrets to tuning. I would love to try or own some from these fellas but I am always impressed with John Thomas's work and he's only 150 miles from me now. Use to be about 20 miles apart. John's work as a tuner is what converted me from fighting a box store springer, junk scope and mount, to a refined tack driver.
If I had never made that crossover I would be none the wiser & never attained the knowledge of what a well tuned springer can do. And believe it or not I have seen this 48 .177 I have from him hit dead on after a entire night in 16*F cold. I mention it because I don't think most untuned rifles would do that. Moly may be the answer. Tar would probably have stiffened up.
These are questions most people don't ask tuners. Can you tune it for hunting in cold? What's best for a given scenario, etc?