What makes airsoft guns accurate?
 

Well, from what I hear the barrel length, muzzle velocity and internal mechanics (bolt action vs gas operated) effect the accuracy of a gun.

Although, are there other things in airsoft guns that make accuracy?

Like I read somewhere on the forum that a Western Arms M4A1 GBBR is a better plinking rifle than a KJW M4A1. So, I'm assuming that the Western Arms M4A1 is more accurate. Overall can anyone explain why is the WA M4A1 is a better plinker?

consistancy of FPS between shots (consistant airseal), hopup, bore of the barrel and length of the barrel to a certain point. Barrel doesnt effect as much as you think it would, but shortened to a point obviously accuracy will be effected, as well as large bore would make a bb bounce around.

Higher FPS will increase your maximum range. "Accuracy" is a measure of the ease of hitting "something" out to your max (effective) range. So no, higher FPS (within reason) does not equate to higher accuracy, persay. ALTHOUGH, with a higher FPS gun you can run heavier BBs which will be more accurate in the real world due to their higher resistance to deflection by wind and leaves.

This. You are almost right. Its really the consistency of the bore of the barrel. You could have a 6.08mm barrel with a very very smooth finish and as straight as an arrow and a 6.01mm barrel with an okay finishing and 'meh' quality and the 6.08mm barrel will be more accurate. Length of the barrel means very little, you really only need the first 4 inches of your barrel. The longer the barrel, the more possible inconsistencies meaning less accuracy.

The way you install your hopup and what type of hopup system you have also plays a role, as well as the bbs and hopup rubber and spacer. Also, how far your air nozzle pushes your bb forward has something to do about when the bb will make contact.

Also, the vibration of your barrel. You will notice that most guns are alot more accurate on semi auto than full auto, because when the piston is hitting the cylinder head the vibrations are sent through the mechbox shell and through your hopup and then onto the barrel. This can me avoided by 'shimming' your inner barrel to your outer barrel in 3 spots: Close to the hopup, in the middle, and at the end of the barrel.

Edit: More on bbs. These are the worst things about accuracy. Better consistency of bb the more accuracy. Don't cheap out on BB's you could get increases of accuracy by just choosing the right bb weight and brand.

Thanks for the anwsers.

Getting more to the point, are these the reasons why an KJW M4A1 is not as accurate as an WA M4A1?

Also, if the WA system is more accurate? Is it possible to buy an AGM M4A1 (WA clone) and replace the hop up, bucking and barrel to make a good accurate M4A1?

About BBs. I plan to use BB Bastard .20 for games then Silica BB Bastrads for basement plinking.

0.20g BBs are barely good enough for CQB, let alone longer indoor distances. If all your shots when gaming are under 40ft, then go for them, but for outdoor use, 0.25g are barely adequent considering most use 0.28g BBs, which will both out range an out penetrate (brush, leaves, etc) your 0.20g.

Higher fps only increases range to very very limited effect within our (typically) 490fps limit
Myself and several other well known gun doctors have proven in the field that a higher fps gun with poor compression will be outranged by 350fps of excellent compression.
It's all about compression!

Brit hit the nail on the head. The BB's is never supposed to come into contact with your barrel. Higher quality = better consistency. Better compression = more pressure behind the BB = the BB won't touch the walls of the barrel = more accuracy.
And to back up what he said, the quality of your hop rubber will play a HUGE role on your range.

The peak performance of your rifle can only be as good as the base you build it on. If you buy a cheap receiver, don't expect the upgrade parts to perform as well as the receiver they were designed to fit in!
Case and point; a chinese VSR-10 clone takes significantly more labor, tweaking and maintenance to shoot as well as a marui VSR-10

Watch your force with gas guns though, they don't work like AEG's when it comes to FPS. An AEG with a cylinder ported proportionally to it's barrel length will show very consistent joules of force using any weight of BB. However, a gas gun typically shoots with more joules of force on heavier ammo.
For example, I know that my WE PDW will shoot at 1.34j of force with .20g BBs, but it will shoot at 1.55j with .28g BBs (that's the equivalent of 410fps with .20g)

If your using bastards, you can't go wrong with .28s, especially around the 1.34j range. Amos has upgrade parts for the KJ's if your interested!

The western arms M4 is a better plinker in the sense that plinking is all you can do with it lol

If you buy a WA, expect to replace EVERYTHING.

IMO (And several other people) the KJW is the way to go for M4 GBBR's.

Right, +1 on that, they're WAY cheaper both out of the box, in upgrades, magazines, and in long term reliability.

For the next year with airsoft, I'll probably be 80% plinking and 20% at games.

That being said, I am more interested in an accurate M4A1 that can get good groupings when you shoot a paper target. So, is the KJW really a better GBBR for developing accuracy skills?

I rather have KJW m4 anytime...

Yes, but using swinging coins instead of paper targets lol

So no, KJW is not the best for a basement target practice?

a pellet gun with a proper back stop would be best for basement target practice.

That has alredy occured to me, but I might try to do everything with on rifle. To game and target practice. Not to mention, the operation on an M4A1 is cool.