:doh: Let me preface this novel by stating these are only MY opinions and ramblings on the subject based on events in MY life. I am not an engineer nor am I an accredited scientist. I do however have an associates degree in aircraft maintenance along with military training and 4 years experience wrenching on fighter jets. Mainly on air and hydraulics systems. I have a basic knowledge of machining and like to tinker. I also don't claim to know everything (I know I can come off that way at times). If you think I am full of crap or a bit off feel free to call me on it. You won't hurt my feelings I promise. However if you do call me on something don't just say "Your full of crap!" and then have nothing to back it up. I will want to discuss it. If I find out I am wrong or something simply doesn't make sense I will own up to it. But if it is something I have seen for myself, I am sorry I can't un see something I have seen after all. These ramblings I post are really just for entertainment and to get people thinking. I am old enough to know that some things that shouldn't work do, and some things that look good on paper or in theory just don't work when you put them to practical use.
Why your airsoft rifle just isn't that accurate
Why your airsoft rifle just isn't that accurate
Of all the weapons platforms I have used Airsoft seems to be the least accurate. And I would like to discuss why I feel this is so. First a little background on me. Since I was young I have been an avid shooter and archer. I have hunted and competed on a regional level in archery, airgun, rimfire, black powder and 6mm bench rest. I will be honest and tell you I have never won any titles, awards or trophies, on my best days I would consider myself an average competitor. I am not the worst shot in the world, but I am by far the best, or even close to being in the top tier. And it had nothing to do with the fact that other shooters were sponsored or had better equipment than I did. They were just simply more dedicated or more skilled than I was. Now I just shoot for fun with no stress or pressure, and I like it that way. I do however have enough experience that I know the mechanics behind it and what makes a platform accurate, or in this case not so accurate.
I am not here to talk down on airsoft or say that the guns are worthless pieces of junk. They are accurate enough for what they need to be, are a blast to shoot, cheap to shoot, and holy crap, you can shoot other people with them! For a low powered non lethal gun they actually shoot better than I would have thought they could. They are more accurate than paint ball markers, which I have experimented with as well. I simply want to discuss the mechanics behind it and why they are flawed from the start where accuracy is concerned.
Let me first define what I consider to be "accurate". To me, an accurate platform is anything that can repeatedly shoot 3 inch groups at its effective range. I know you will hear a lot of people talk about sub MOA groups at hundreds of yards. While it can be done, most of it is just talk. I have very rarely met a person that can actually shoot as well as they claim when talking themselves up. And the ones that can shoot that well normally don't brag about it. MOA is Minute of Angle and it equals 1 inch at 100 yards. 3 inch groups at 100 yards would be 3 MOA, and I would consider this average for most shooters and rifles that have that kind of range. Rimfire rifle I consider to be 50 yard weapons and air rifles about 20 or 30 meters. Modern archery is actually more accurate than you might think, I can hold 3 to 4 inch groups at 70 meters IF I KNOW THE YARDARGE! At those ranges being 5 yards off can make a big difference in your impact points.
For hunting I call it Minute of Deer, which means if you can put your shots in an 8 inch circle it will humanely kill the animal. You simply don't need to shoot sub MOA groups to hunt medium to large game. Long range varmint hunting is another story though. For airsoft I call it Minute of People. Lets be honest, all you really need is to be able to hit a human sized target anywhere on the body, at fairly close ranges. This roughly equates to a 4 foot tall by 2 foot wide target. And you don't have to hit them in the vitals, you just need to make contact. If you drop a shot 2 feet low and hit them in the ankle it is still a kill. And if they are honest and call their shots you only need to do it once. Unlike real game where it might take multiple shots to actually stop the target. And in most cases, lets be honest, you can do this without using sights. Sure that big scope or fancy eotech sight looks cool as hell, but you really don't need it to be effective. Decent open sights or a simple reflex sight is more than enough.
If you use my 3 inch group theory, then most decent airsoft guns have an effective range of around 20 or 30 yards, maybe. This means 20 yards is about the distance one of these guns can effectively shoot a 3 to 4 inch group. I understand some people have airsoft rifles that are much more accurate than this, if you are one of these people I tip my hat to you and say consider yourself blessed. Inside of 20 yards most of my guns are actually pretty accurate and quite fun to shoot ( I currently own 8 airsoft guns.). My M4 and P90 will easily rip single holes about 1 inch in diameter in full auto at 10 yards.
That being said, 3 inch groups really are not a fair standard for airsoft. That is actually way more accurate then you realistically need to get the job done. For airsoft you really only need to be able to put a bb in a 24 x 48 inch area at a given range. So the effective range of an airsoft rifle becomes the distance at which you can consistently hit a 2 foot by 4 foot target ( human torso). For most airsoft guns this can be achieved at 50 or60 yards, for a well tuned gun or a decent sniper rifle 300 feet (100 yards) is not unheard of and seems to be the goal most aim for. Then when you factor in most airsoft guns are quiet, have little to no recoil and bb's are cheap follow up shots are not an issue. If it takes you 5 or 6 shots to walk a bb onto a target it isn't the end of the world. And to be perfectly honest in real combat this happens more often than you would think. This is one of the reasons real snipers have spotters.
So why cant your 300 dollar, or in some cases your custom rifle you have way more into, spit bb's into a 1 or 2 inch circle at 100 yards like a real AR or Remingtion 700?
What is the number one factor in accuracy? Consistency, that is quite literally the definition of accuracy. Being able to repeatedly do something with the same outcome. An accurate weapons platform needs to be consistent from shot to shot. Without that, all hope is lost. Unfortunately airsoft guns fail at this on several levels.
The number one thing airsoft rifles have against them is BB's. To be perfectly blunt, round projectiles suck. There is a reason no weapons use round balls anymore. One of the biggest advancements in weapons technology was switching from round ball to conical bullets. After that would be rifling and percussion caps. This is why your daisy or crossman .177 bb/pellet gun will always be more accurate with pellets instead of bb's. A bullet is longer than it is wide. And it either has rifling to spin it on axis or is heavier in front with a skirt in the back. This makes the projectile more stable while in flight. Added mass doesn't hurt either. Bullets and pellets are also normally slightly larger than the bore, or have a soft skirt in the back that expands under pressure. This gives a better seal and more uniform pressures and velocities. BB's are normally hard and slightly smaller than the bore so they can more easily get down the barrel and not get stuck. The downside is gas is wasted going around the projectile and they are not very stable once they leave the barrel.
And to make matters worse for airsoft we use extremely light bb's that are not very consistent. Weights seem to be pretty good from bb to bb (because they are so light to begin with) but diameter, shape, internal consistency, surface texture and balance tend to not be very good. I don't care if you have the best, straightest, laser polished barrel that is accurate to .0001 of an inch, if your bbs are not perfectly round and sized it was a total and complete waste of effort. And I have measured bb's that were off by more than a thousands of an inch from one spot to another, let alone from bb to bb. This means they are not perfectly round, or balanced. And the way the bb's are constructed doesn't help either. They are designed to be light, hard and fragile. They are made to do the least amount of damage as possible when hitting a target. We don't want them to carry a lot of energy, and we want them to shatter when they hit something hard. Neither of these are good qualities when looking for an accurate projectile.
In the world of long range precision shooting 30 caliber is pretty much where it's at. So a .308 or 7-8mm projectile that weighs between 150 and 170 grains. This gives you a bullet that has a length that is long enough compared to its diameter to give you a good ballistics coefficient. And even though it may not shoot as flat as a lighter faster bullet, it tends to be more accurate when it actually gets there. The shape of the bullet also effects its BC. You don't just want a solid cylindrical slug sailing through the air. You want it to be air efficient and well balanced. And with a real projectile we normally look for something that is hard enough to hold its shape when moving at high speeds, yet soft enough to form to the barrel and expand when it hits a target. But still not being so hard that it doesn't break apart and shed off energy. None of these are qualities a 4 grain plastic bb posses. Ok, so a bb doesn't travel at 1 or 2 thousand feet per second, it is more like 300 to 400 fps.
You know what goes about that speed and is very accurate? An arrow that is an average of 28 inches long, weighs 450 grns has a balance point about 1/3 from the front and has large fletchings to create drag and stabilize it. Even a .177 caliber lead pellet weighs between 7 and 10 grains and is about twice as long as it wide. And is made of soft lead. You can buy very hard alloy pellets that are light, but I can assure you they are not very accurate. They are fast, but not particularly accurate in most guns. Mostly they are made so airgun manufacturers can say their specific rifle shoots 1200 fps or faster. Sort of the same thing as testing an airsoft gun with .12 or .20 bb's. The numbers look impressive, but its probably not what you are actually going to use in the field.
The next hurtle is how the bb's are propelled from the barrel. In order for a projectile to be accurate at a certain range it needs to leave the barrel at the same velocity from shot to shot. Unfortunately because of the power systems, and because of the bb's airsoft guns are not very good at this. Green gas being the worst, then unregulated CO2, after that AEG's and then spring sniper rifles. There is a reason HPA guns are more accurate, it is because they do a better job of metering the air charge. They also dump a lot more air behind the bb which reduces the effect of air leaking around the bb. It still does it obviously, it is just that there is enough air that it doesn't effect the velocity from shot to shot. And with the polarstar system there is a whole slew of adjustments you can make to effect the pressure, duration and timing of the air charge. You want range and accuracy, use a wide bore barrel and flood that sucker with air. Down side is uses more air and you get less shots per bottle. If you want to conserve air, use a tight bore barrel and use just enough air to get the velocities you want. Down side, not quite as accurate as the wide bore.
I would say the next best system would be regulated CO2. As long as you are not making rapid shots and the tank pressure is higher than the regulator pressure it should be pretty consistent. Green gas, propane and unregulated CO2 just isn't very consistent from shot to shot due to the cooling effect as the gas is expended and changes from a liquid to a gas. And the faster you shoot, the worse it gets.
Manual spring guns (sniper rifles) are not too bad. If you have a good spring and a well sealed system they can be pretty consistent. Better than green gas for sure. And AEG's tend to not be real consistent either. I don't know if it is because of the electrical mechanics, the piston seal or type of springs they use. Or most likely a combination of all those factors. What this means is even if you had perfect bb's, a perfect barrel with a tight seal and your velocities had a standard deviation of 50 fps or more you can pretty much kiss any kind of real accuracy goodbye. At longer ranges anyway. Inside of 10 or 15 yards it probably wouldn't have a large effect. And the slower your projectile the more that spread has an effect. If you are shooting 2500 fps with a 170 grn bullet then a standard deviation of 50 might not be too bad (I would want better), But with a 4 grain bb moving 275 to 300 fps that is a big deal. And with a bow that would be horrible. If you were seeing variations like that you better be checking our arrow weights, or the limbs and cams on your bow. I would actually worry for my safety if my bow had that kind of spread from arrow to arrow.
Another factor would be the receiver and barrel system. For accuracy you want a rigid sight, receiver and barrel connection. Both inner barrel and outer barrel. I have seen some AEG's where you can grab the outer barrel and wiggle it, my 249 saw does this because of the way the barrel connects. This is not good for accuracy. This brings us to barrel spacers/bushings. To be honest, you really only need one at the muzzle end of the barrel. You only need enough support to make sure the barrel is pointed in the same direction from shot to shot. Vibration and harmonics really don't play much of a part in airsoft. There simply isn't enough energy produced to cause barrel whip like on a high powered rifle. As long as your outer barrel is rigid and tight with the receiver one bushing or O-ring at the muzzle end to center the inner barrel should be plenty. And obviously you want your hop up to be solidly mounted as well. I don't care how tight your inner barrel fits, if you can wiggle your outer barrel it is a lost cause.
How do I know barrel vibration and whip is not issue with an airsoft rifle? Because it is not an issue with high powered air guns. My pellet gun can shoot a 10 grain lead pellet at 900 fps. The piston hits home hard enough to create reverse recoil and destroy cheap scopes. And the barrel isn't affixed to the receiver, it breaks open just before the scope mount. Barrel vibration isn't an issue in these rifles. Overall vibration is though, this is why they require a different and more consistent hold to be accurate. If you hold the gun tight for one shot, then loose for the next it will actually change the impact point of the pellet. This is why PCP (HPA) air guns are so much better. They are way more forgiving to shoot accurately. I have tried this technique with airsoft guns and it didn't seem to make a difference, so the shock and vibration must not be bad enough have an effect on the over all system. However, if you are shooting a bolt sniper gun with a heavy spring that shoots over 550 fps it wouldn't hurt to emulate the shooting form of a good spring air gun shooter.
And this brings us to everyone's favorite part of the airsoft gun. The magical part that lets us shoot a light 4 grain round bb moving at 300 fps out to 100 feet or more. The Hop Up! Some genius figured out that by using simple physics and aero dynamics we could put a back spin on the bb giving it lift and defying gravity enough to double or triple the effective range at lower velocities. Unfortunately the physics behind the hop up system are actually horrible for accuracy lol. Adding friction to the top of the bb at the beginning of the barrel just intensifies and exaggerates every other flaw in the system.
Think of how the hop up system works. It is a small patch of rubber that is either flat or has a small nub on it. A lever lowers or raises this section to adjust how much pressure, or contact it will have with the bb. The forward moving bb hits this small patch of rubber and friction causes it to spin backwards as it travels down the barrel. Now lets think of all the things that can go wrong when this happens. For starters, having your projectile purposely strike something while traveling down the barrel is something most would want to avoid at all costs. Then again, most projectiles are not round either and this sort of contact would serve absolutely no purpose other than to destabilize it and slow it down. So with a round bb it is actually something you can kind of get away with. Sort of the same principle as using feathers on an arrow. It would seem like purposely slowing the arrow down would be counterproductive, but shoot a bare shaft arrow once, it is kind of scary. If you are lucky you might actually hit your target. If you are really lucky it won't hit at some goofy angle and break your arrow. You can tune a bow to shoot bare shafts, but it takes time and REALLY good form.
So the hop up is using friction at the top of the barrel to make the bb spin backwards as it travels down the barrel. Lets ask ourselves exactly what is going to regulate the amount of and direction of this spin. And what happens when the bb leaves the barrel. Some buckings are hard, some are soft, some smooth, some are rough, some have teeth or nubs on them. This surface can wear down or change after extended use. Temperature could effect the thickness or texture quality. How accurate is the spring holding tension on the device, and can it back off or change from shot to shot (yes it can, and does). What if the bucking is dry, wet, dirty or possibly gets oil on it. These would effect how much friction it would impart. Then we have the bb itself. We have already established that bbs are not perfectly round, balanced or have a perfectly uniform surface. If one bb is larger than another, is not perfectly round, perfectly balanced or the surface finish varies from bb to bb this is going to effect the amount of spin the hop up imparts because it will vary the amount of friction from shot to shot. Also the speed at which the bb is moving when it hits the hop up will effect it. And we have also established in most systems there is a fairly large standard of deviation in velocities from shot to shot. Faster bb, more spin, slower bb, less spin.
How accurate and centered is the hop up nub on the bb. And if the bb's are smaller than the chamber or of varying sizes what controls whether the nub is perfectly centered on the top of the bb? And since the bb is spinning and creating lift when it leaves the barrel then the barrel must be vertically centered for each shot. Meaning if you cant the barrel slightly to the left or right the bb will get pulled in that direction rather than straight up. Same thing with if the nub doesn't contact the bb on the direct top center of the bb. If it is a little off to either side it will impart some kind of odd spin to the bb. And instead of creating lift and extending the range it will instead pull the bb off to one side or the other. Or in some cases just do some crazy stuff in flight. I have seen bb's literally bounce around and zig zag in the air on their way to the target.
And this is all considering the bb doesn't make contact with an extra long outer barrel, muzzle device or suppressor on the way out. Since the bb will start lifting after it leaves the inner barrel if you have too much material after the inner barrel ends you may have contact issues that will really mess up the bb flight.
The funny thing is the part most people worry about is the most precise part and probably has the least impact on performance, the barrel. Even the cheapest of airsoft barrels are over engineered to the point of ridiculousness. When compared to the bb's the barrels are insanely well built. Sure a longer barrel might give you a bit more fps, or a little tighter grouping at 15 yards. Beyond that though they are actually the best built part in the whole system. There are HPA guns with 200mm barrels that will range out to 300 feet. With the proper bb and hop up adjustment.
And Oh My God, what is up with people dropping hundreds of dollars on high end barrels, springs, pistons, optics and triggers and then using whatever bb some chart or person suggests on the internet! Or grabs some cheap bb's from Walmart. You would probably be better off leaving your gun stock and spending the money and time to try every brand and weight of bb to see which ones actually shoot the best out of YOUR rifle. I can't tell you how much time and money I have spent trying different ammo and working up hand loads for my various rifles and handguns. There is no reason the same would not apply to airsoft. And the whole barrel to cylinder ratio thing, it is a decent guide and place to start. However by no means is it the holy grail to what will work best in YOUR situation. I experimented with my little P90 and it ended up liking a 385mm barrel with a ported cylinder and .29 bb's. The math doesn't really add up, but who cares, it shoots awesome. Do I believe math and theory, or do believe results? Kind of bums me out because it is the best shooting gun I have, but I think its butt ugly lol.
Could you make an airsoft rifle more accurate? Of course you could, just employ the same techniques and technology we use in higher powered air rifles. Deliver more volume and more accurately metered air charges (HPA/PCP). Use a softer, heavier, longer skirted pellet instead of a hard, round bb, and do away with the hop up system. Rifling the barrel might help, but honestly the barrels have such tight tolerances already it probably would not be needed unless you wanted to be accurate at longer ranges.
The problem with this is you just completely changed the role of the weapon. It would no longer be a medium range weapon with low enough power that you could safely shoot at each other with it. You would have turned it into an accurate close range target gun basically only good for punching holes in paper. It would lack the power or energy needed to harvest even the smallest game. And since you made the projectile heavier and did away with the hop up, if you wanted it shoot to 50 yards or so the energy would be high enough no one would want to get shot with it. If you shot someone at 20 yards with one it would most likely break the skin and even possibly break or shatter safety equipment like masks and goggles.
You would also have to totally re design the magazine and feeding systems. Round bbs are MUCH easier to store and load then pellets would be. You would have to design a feed ramp and it would really limit magazine capacity. I have seen a few gas guns where I think you could get away with it though.
I do see where there could be a practical use for it in sniping situations only. 5 to 10 round clips, or even single load in a bolt action spring or gas gun. I bet some sort of soft longer pellet would be twice as accurate as a bb. The only problem is you would really have to limit your engagement distances. All it would take is for one crazy kid or an aggressive adult to shoot someone at close range and it would ruin it for everyone. Or someone repeatedly aiming for bare skin with no protection.
It would be a cool project, but truthfully you could just by a pellet gun that would be cheaper and work better lol. You can get PCP rifles for as cheap as 300 dollars now.