What i do see with newer pcp guns is 1 now most are regulated , the biggest improvement is efficiency more shots with air, I feel prices are extremely over priced with guns and slugs , Today 22 rimfire bullets are cheaper then 22 slugs come on , a rimfire had gun powder and brass ,
If you look at real center fire guns they dropping in price , I can buy a gun for sub 400 and shoot out to 1000 yards , 10 years ago you had to spend 3x to be even close , I believe the air gun market is over priced , but i love my hobby ,
AS far as accuracy it has improve , But entire gun industry accuracy has improved , in 1990s I shot 1000 yards , which was world class , today a ultra long shot is over 4000 plus yards ,
here is todays rifle standards
0 - 300y point blank range
300 to 800 short range
800 to 1200 medium rang
1200 - 2500 long range
2500plus ultra long range
this was unheard of a decade ago
I would have to say scopes have improved more then guns with technology , the glass today is fantastic , now tier 1 scopes use apochromatic lens and Low dispersion glass , so it is easy to see things at ULtra long distances which were unable to see a few years ago , I would say Glass improved so much , I can shoot at very low power out to 1 mile like 6x to where as prior we used hi mag glass which just distorted images , so I believe scopes advanced most , and prices are up as well some tier 1 re dropping in last 2 yrs due to new models claiming bleeding edge .