And you must keep in mind each air gun has it's own personality. So there are no Absolutes for each gun. Here are a few reasons why, a barrel may be born a little different size. barrels maybe made on different machines.All kinds of things happen in the real world.A air gun may not shoot the same pellet as well as another gun the same model.
And springs and internals may vary a little ..Giving you different results. Now let's think about wear on a spring this is where the break in period comes in to play.At first the spring wears more and starts to settle into place and wear slows down.this is why velocity changes so much at first and it won't ever really stop.But change slows down alot.A pro tune will help this greatly.As metal parts are polished and compounds of some sort are used to keep wear down and make the parts of the gun operate smoother .
Of course it helps to know the characteristics of each model and brand gun.This is also true when it comes to pellet size .177.22.20.25.ect
Due to the way a gun is designed two guns with the same ft,lbs one may shoot pellets of same size different.To me ..ACCURACY MATTERS..ACCURACY MATTERS..after all with out it what do you have? The guns I tend to like are the ones that shoot the heavy .177 well I have always thought the .177 are more accurate, but the lighter pellets don't keep the power down range . So a .20 or .22 will hold it's speed for a greater distance then the .177.
My rws 54 spiten a 10.5 .177 cp has plenty of punch at 50-60 yrds . some people will tell you that the rws 48/52/54 has too much power for the .177 round.To be honest I bet the .20 would be the right one for these models.And that is what I mean different model guns will work best with one of these pellet sizes.And if you find it's best combination ..You have a true winner.ACCURACY, DISTANCE ,KNOCK DOWN POWER. However, keep in mind what you want the gun for and go after the one that will suit your purpose best.A few of Chinese guns are ok pest control..But, ask, around for people who own one and can tell you about that model.They can be as good as guns costing three times as munch.And depending on what you plan to do with the gun .Maybe it makes sense to get a cheaper one.When I hunt I don't like to worry about scracthing my gun.On the other hand, if you are going to shoot FEILD TARGET a very smooth shooting gun. and one to show off.May be what you want. I have a tuned RWS 46 for that..Oh and keep in mind there are a lot of trade offs when looking at air guns..Pump guns are noisy to hunt with.i.e.the pumping.spring guns kick and can be hard on scopes.PcP cost a bunch and have a lot of bagage.Co2 guns don't work well in cold weather.There are forms on line with guys to help you..However,There motives may not always be clear ..some want to sell you stuff and others just like one brand no matter what..The best SERVICE and best gun at the best price is what I think is the GOOD deal. Ask if you can get your money back if you are not satisifed. ALWAYS BE SAFE AND HAVE FUN...
