What is the Best Barrel Length for 45 ACP?
Today we are leveling an ideological strike against the cliché “more barrel equals more better.” This idea may take the form of statements like:
“The longer the barrel the more accurate.”
“The longer the barrel the flatter shooting.”
“The longer the barrel the higher the velocity.”
The truth of the matter is that while those may manifest as true statements, they are only true under controlled circumstances.
Today, we break that control in an effort to answer the question “How much Barrel is too much Barrel”?
CMMG MkG 45 ACP
The plan was to make an abnormally long barrel and record the velocity data. After data was recorded, we would then cut the barrel back inch by inch taking 10 shots at each length.
To accomplish this, I reached out to one of my industry partners at CMMG. For those unfamiliar, they are known for breaking the status quo and always pushing development of new arms. One of those is their pistol caliber carbine line that uses a patented radial delayed blowback system to achieve more consistent performance over the traditional direct blowback systems used in PCCs.
They expressed interest in the idea to look at their next generation of barrels.
Although their PCCs come in a variety of calibers, we settled on 45 ACP as it would likely give us the most apparent effects due to its mass an speed.
CMMG sent a MkG pistol in 45 ACP, which comes in multiple variants. We ended up starting at 26 inches with a 1:16 4140CM barrel that CMMG custom made for the test.
Disclaimer: DON’T chop your barrel. VSO is licensed to do that kind of thing and I don’t want you guys to run afoul of NFA regulations. That said, we used a pistol, so the barrel length changing is irrelevant.
Testing
We used Fiocchi 45 ammo, which is their 230gn FMJ range ammo.
For a control, I brought out my Glock 21. This would give us a consistent barrel length to compare throughout the multi-day test. The Glock is used to test the velocity of the ammunition for a consistent measurement to compare against the CMMG.
The truth of the matter is that science can often be repetitive and boring. It’s my job to condense that down a bit for you so it’s a bit more palatable. To do so, I have put together this video discussing the finer points.
While there was a great deal of information derived from this test, I thought the following questions were the most important in the lead up to testing:
- Does the first round get stuck? As in is 26” really too long.
- Where are we going to get the highest velocity?
- What is the most efficient barrel length for a 45 ACP PCC?
Results
As you saw in the video, the 26-inch barrel is not long enough for a 45 to get stuck inside the barrel. However, according to some calculations, a 40-inch barrel would create a situation in which the drag of the barrel would cause the bullet to get stuck.
At what barrel length do you get maximum velocity? The answer is 15 inches, with a speed of 989 FPS. If you look at the average of each shot string, and not a single outlier, you also get 15 inches. The average for the ten shot group was 966 FPS on the 15-inch barrel.
What is the most efficient barrel length for a 45 ACP PCC? There are a lot of variables to consider.
First is the standard deviation between each shot. This data is essential because a significant swing in standard deviation can have a major impact on accuracy.
Second is how much velocity percentage is achieved of the maximum velocity with minimum barrel length. There is no doubt that a 15-inch barrel is the best length for max velocity; however, for the best overall standard deviation, 11 inches is the best barrel length.
Having an 11-inch barrel has some advantages. The addition of a standard silencer to an 11-inch barrel gives you a gun with roughly the overall length of a standard AR-15. So if you train with an AR, then you would not notice an increase or decrease in length. So, the transition would be smoother.
The CMMG MkG 45 is available in 5-inch, 8-inch, and 16-inch. If you look at the charts below, you can see the data for each of those barrel lengths. You can also click on the charts to view the shot strings or download the PDF.
Owner of the VSO Gun channel and President of VSOrdnance, a firearms industry R&D firm. Curtis specializes in breaking new products if there is a weakness he finds it. From firearms to accessories VSO covers it all.