I recently had an opportunity to fire the same 223 Remington ammo over a chronograph out of 3 very different barrel lengths, and recorded the muzzle velocity differences I observed. The chronograph was an Oehler 35p, which is one of the most accurate in the industry. The ammo fired was Federal’s 55gr FMJ ammo, and all of it was out of the same box. Here are my measured results:
|Barrel Length (inches)||Average Muzzle Velocity (fps)|
Here is an inferred trendline based on the measured velocities for other 223 Remington barrel lengths. 5.56 barrels would likely be very similar. The blue bars indicate actual measured velocities, and the gray bars indicate an inferred muzzle velocity.
There is much debate on how much velocity is lost when you start chopping down the barrel, and there are even a few people that think velocity loss is a myth. That is ridiculous. Although the amount of loss for a particular cartridge and barrel length is still up for debate (and is debated fiercly on many forums) … the fact is that there is virtually always some velocity loss when you reduce the barrel length. Now how significant that is, and whether it is worth it for your application is up to you.