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There are debates on whether airsoft inner barrel length makes a difference when it comes to accuracy. Unlike real firearms, where the bullet travels over 3000 feet-per-second (FPS), lighter airsoft BB travels below 400 FPS. This huge difference in energy begs the possibility that airsoft barrel length makes no real world difference.
In this article, we will use a controlled, simulated environment to determine whether the difference in inner barrel length makes any real world difference in a CQB environment. The intended purpose is for real airsoft battle, not gun-on-the-vise shooting competition.
We downloaded the following free target from Evike's web site. This target has inches markings. But Evike provided a raster (JPG) image, not a vector file. Therefore, when we printed the image on our laser printer, the target wasn't to scale. The 7" marking was extremely close to 7 centimeters on our print out. Therefore, it provides a good relative measurement.
For this test, we used an APS ASR106 Mini Patriot M4 and an APS ASR107 M4 URX Raptor. The two guns are so similar that we were able to interchange parts in order to create a highly controlled test with very little variables. For example, we used the gearbox and lower receiver from the URX Raptor with the Mini Patriot stock (see photo below) in all of our tests.
The APS ASR106 Mini Patriot M4 comes with a 175mm steel inner barrel (see photo below). This inner barrel is mounted in a Bravo metal hop-up unit. The hop-up unit has been adjusted to be accurate and precise out to over 30 feet in an outdoor environment.
The APS ASR107 M4 URX Raptor comes with a 275mm steel inner barrel (see photo below). This inner barrel is mounted in the stock metal hop-up unit. The hop-up unit has been adjusted to be accurate and precise out to over 30 feet in an outdoor environment.
We will use the Barska Red Dot Scope on the URX Raptor upper receiver (see photo below) for this test. The Barska Red Dot Scope has been zero in at over 30 feet in an outdoor environment. The 175mm inner barrel is just slightly longer than the external barrel without the mock silencer. Therefore, that's the configuration we will use to test the 175mm inner barrel. The mock silencer will be attached when we test the 275mm inner barrel.
In order to eliminate the red dot sight precision as a factor in this test, we introduce a second red dot sight into this test. The second red dot sight is a Ultimate Arms Gear Tactical 4 Reticle Sight JH400 that is zero in at over 30 feet in an outdoor environment. It is mounted onto the Mini Patriot upper receiver (see photo below). We will use this assembly to test both inner barrels as well.
We used 0.2 gram BB's in all of our tests. This is the most common weight BB's. In an indoor controlled environment, BB weight should make very little difference in the outcome of this test (but sounds like a good test for another day).
The controlled environment is a dim garage to eliminate external atmosphere factors. The target trap is located 20 feet from the shooter. The shooter will hand-hold the shots to simulate real combat situation versus using a gun vise. 10-rounds will be fired into the target trap in semi-automatic mode. The shooter is free to take as much time as possible (within reason) to make accurate shots. Aim is performed with a single eye open (in order to reduce error) with the red dot directly on the center of the target (no manual adjustment of the shot is allowed). The red dot brightness is set to 1 on both sights in order to keep the MOA as small as possible, but highly visible this dim environment.
The first test was conducted with the 175mm inner barrel with the Barska Red Dot Sight. Test result is shown below. Grouping is well within a 7 centimeter square at 20 feet, which is precise enough for CQB situations.
The second test was conducted with the 275mm inner barrel with the Barska Red Dot Sight with the mock silencer. Test result is shown below. The grouping is amazing--within 4 centimeter square--compared to the first test with the 175mm barrel.
In the third test, we eliminate variables caused by the Barska Red Dot Sight. We went back to the 175mm inner barrel and used the Ultimate Arms Gear (UAG) Red Dot Sight. In practical use during airsoft combat, we found this sight to be highly accurate. The test result below shows grouping in a 4 centimeter square as well, verifying our sight accuracy claim.
In the fourth test, we used the 275mm inner barrel with the UAG Red Dot Sight. The grouping is still tight at 4 centimeter square. However, it is no better than the 175mm inner barrel with the same sight.
Surprised the difference the red dot sight made to the test and no real difference between the two inner barrels otherwise, we performed a fifth controlled test. In this test we went back to the first test configuration--175mm inner barrel with the Barska Red Dot Sight--in order to eliminate the shooter factor; eliminate the possibility that the shooter got better at this test with practice over time. The test result is shown below.
Test result 5 is consistent with test result 1. Therefore we are convinced that the test variables are well controlled.