Barrel Length Matters - Muzzle Flash 16" Barrel with Flash Hider vs Bare 20" Barrel

Muzzle Flash first data

Results from my daytime test comparing ten shots through a 16” AR with a flash hider vs a 20” rifle with a bare muzzle.

Here is the slow motion video of the 10 shots through a 16” AR with flash hider compared with 10 shots through a 20” KelTec RDB with no flash hider. Using this slow motion video, I moved through each shot frame by frame to see if a muzzle flash could be spotted. I spotted 4 flashes on the AR with 16” barrel and no flashes on the 20” RDB.

I am proceeding on the hypothesis that running a bullpup carbine with a 20’ barrel with a bare muzzle is generally better than running a 16” barrel with a flash hider.

For starters, the extra for inches of barrel length, delivers an extra 150 FPS. The extra four inches of the longer barrel extend the hydrostatic shock or fragmentation range of the 5.56 cartridge to something approaching 200 yards vs about 100 yards for the 16”.

I suspect that the muzzle flash of a 20” barrel will not much exceed that of a 16” fitted with a flash hider. A 16” barrel with a flash hider will end up being 18-19 inches long. So why not just get the added velocity?

I suspect that the longer barrel makes for a less harsh gas system, whether direct impingement or piston. And therefore may have slightly less felt recoil...although that may be difficult to detect given the 5.56’s already mild nature.

20” should produce slightly less report than the 16 and is certainly less obnoxious on a crowded firing line.

I also suspect that the longer barrel may be more accurate (using off the shelf ammo) due to the less violent blast and turbulence at the muzzle.

I will repeat this test in low light conditions at the Ambidextral Gunfighter Proving Grounds.

The advantage of the bullpup design, like the Keltec RDB, is that you can have this 20” barrel in a rifle with an overall length that is 5 inches shorter than the 16” AR. Yet another data point as to why I regard the AR/M4 as a relic, a highly refined and perfect platform, but a relic given the features that modern bullpups, like those produced by KelTec and Desert Tech, deliver to the mobile, ambidextral gunfighter.