The video examines how 5.56/.223 velocity changes with barrel length on AR-15 platforms. The team tests barrels from 7.5 inches up to 20 inches using Ballistic Advantage complete uppers, all with the same barrel profile and 1:7 twist rate. A Griffin Armament Mk1 lower is used initially as the control, and later a PWS Mk111 lower is swapped in after some malfunctions to rule out buffer issues. The ammunition is 62-grain M855 PMC X-TAC, a common green-tip steel-core load. Velocity is measured with a Garmin chronograph to keep data consistent. The goal is to see how much feet-per-second is gained as barrel length increases, while keeping all other variables as controlled as possible.
Testing starts with the 7.5-inch barrel, which produces an average of 2,325 fps with the 62-grain M855 load. Moving to a 10.5-inch barrel, the average jumps to 2,596 fps, a gain of 271 fps over 7.5 inches. The 11.5-inch barrel averages 2,679 fps, adding another 83 fps over 10.5 inches. A 12.5-inch barrel records an average of 2,736 fps, only 57 fps more than 11.5 inches. Early results show that going from 7.5 to 10.5 inches yields a large velocity increase, while gains between 10.5, 11.5, and 12.5 inches become more modest. All of these shorter barrels use the same Ballistic Advantage configuration and 62-grain PMC X-TAC ammunition.
The 13.9-inch barrel averages 2,824 fps, an 88 fps increase over 12.5 inches. A malfunction occurs during this portion of the test, likely related to a magazine or buffer issue, so the team swaps magazines and later changes the lower to ensure the uppers are not at fault. The 14.5-inch barrel averages 2,873 fps, only 49 fps faster than 13.9 inches. Moving to the 16-inch barrel, the average velocity reaches 2,942 fps. That is about 69 fps more than 14.5 inches. These mid-length barrels show that velocity continues to rise, but the gains per additional inch are smaller than the jump seen between the shortest barrels.
With the longer rifle-length gas system barrels, the 18-inch upper produces an average of 3,024 fps, adding 82 fps over the 16-inch barrel. The 20-inch barrel averages 3,079 fps, only 55 fps more than 18 inches. Before shooting, one of the hosts predicts the 20-inch might reach around 3,200 fps, but the actual data falls short of that estimate. The results show that while velocity continues to increase with barrel length, the returns diminish at the upper end. The difference between 18 and 20 inches is relatively small compared to the gains seen when moving from very short barrels to mid-length options.
After shooting, the hosts review gas system lengths and how they correspond to the barrels tested. The 7.5-inch and 10.5-inch barrels use pistol-length gas systems. The 10.5, 11.5, and 12.5-inch barrels are described as carbine-length, while the 13.9, 14.5, and 16-inch barrels use mid-length gas systems. The 18 and 20-inch barrels are rifle-length. They recap the averages: 7.5 inches at 2,325 fps, 10.5 at 2,596 fps, 11.5 at 2,679 fps, 12.5 at 2,736 fps, 13.9 at 2,824 fps, 14.5 at 2,873 fps, 16 at 2,942 fps, 18 at 3,024 fps, and 20 at 3,079 fps. The discussion highlights where gains are significant and where they begin to taper off between specific barrel lengths.
The team calculates that the total velocity gain from 7.5 to 20 inches is 754 fps with the 62-grain M855 PMC X-TAC load. They note that some length changes, such as 10.5 to 11.5 inches or 12.5 to 13.9 inches, can yield close to 100 fps, while the 2-inch jump from 18 to 20 inches only adds 55 fps. This leads to a discussion about diminishing returns and how small changes in barrel length can sometimes matter more than larger ones, depending on where in the range they occur. They also point out that while a 20-inch barrel offers the highest velocity, it is less practical for close-quarters use, where a 7.5-inch or other short configuration may handle better. Barrel choice is framed as a balance between velocity and intended application.
In closing, the hosts share personal preferences based on the data. One favors 12.5 inches, especially when not using an 18-inch setup, while another has long preferred 11.5 inches but acknowledges the strong performance of 10.5 and 12.5 inches. They emphasize that Ballistic Advantage uppers performed consistently and that the earlier malfunctions were traced to the lower and buffer system, not the uppers. Switching to a PWS Mk111 lower with a brace resolved the reliability issues. The test is presented as a more controlled follow-up to a previous, removed video, with all uppers from the same manufacturer, identical 1:7 twist barrels, factory PMC X-TAC 62-grain ammunition, and a Garmin chronograph used under the same conditions.
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