I wanted to know why everyone is so concerned about 100yd groups? When someone posts a group the first thing that is said is what about 100yds! Why are you concerned if a pcp shoots 100yds or not? If 50yds are half inch with a particular rifle then 100yds would be close to moa. The deciding factor would be the shooter! Most people don't even shoot past 25/50 yards when pesting/hunting. Is it a Macho thing my gun shoots better then yours deal? All the 100yd shooters are you guys shooting EBR with your 100yd lasers? Probably not
You've received some very good answers here in this thread...I would only add the fact that technology has closed the gap in between airguns and powder burners regarding shooting range and also power to some extent and this has much to do with this cliché...
Measuring the accuracy or powder burners at 100 has been a tradition that we inherited, back in the 50's -60's when powder burners were not as precise as modern guns, a 1"at 100 (1 MOA) gun was exceptional for hunting...The other cliché was sighting in your center fire 3" high at 100 (hunters) independently of caliber or trajectory...Going hunting you invariably sighted in your gun 3" high at 100 !
I believe that the use of 1 MOA in airguns is just something we inherited from powder burners...It is not about the distance people shoot because as you well say, most of us shoot no further than 50 yards in general; nevertheless, knowing that your gun is capable of 1" at 100, .500" at 50 or .25" at 25 kind of gives shooters much confidence in the precision of their guns...To some other shooters 1 MOA means bragging rights... "My gun is very precise, it shoots 2000 pellets inside a 1" group at 100 yards"
Given the trend in power end extended range achieved, I am afraid some of those liberal politicians in the USA will soon be regulating air gun power or airguns in general; nowadays you can easily shoot a 40 gr. pellet at over 1000 fps. and this power is comparable to a .22 RF...I am just waiting to read about the first assassination or mass murder committed using an air gun...But this is another topic and in the meantime let's enjoy what we have!
Best regards,
AZ