Do Muzzle Brakes Affect Group Size? - Inside MDT

Posted by William Maxwell on 2024 May 2nd

Do Muzzle Brakes Affect Group Size? - Inside MDT

Editor's Note: In this article, William Maxwell performs a quick test to determine how muzzle brakes affect group size. This is not a Brand A vs. Brand B article but merely a test to show that a muzzle brake can open up groups and possibly affect velocity.

It never ceases to amaze me how many variables affect the performance of precision rifles. Something that was recently brought to my attention is the style and size of muzzle brakes. A friend mentioned that he noticed some variation when he switched from a 6.5mm brake to a 6mm for his 6mm BR. This got me thinking: I currently have a decent number of different brakes floating around the bench. Why not shoot them all and see what we find? After all, I am getting my rifle ready for match season; we have to find out which brake will produce the best results regarding group size and potential point-of-impact shift.


For this test, I am using my purpose-built PRS rifle. The heart is a Curtis Custom Valor, Trigger Tech Diamond, and 26" IBI MTU profile barrel chambered in 6mm BR.

It lives in an MDT ACC Elite, with all the MDT accouterments. For glass, we're using the Gen III Vortex Razor 6-36x56. Shooting is done from a bench with a PRS model Ckye Pod and an Armageddon Gear Shmedium rear bag. The barrel was fully cleaned before the "test" trip. Before the testing, 5 rounds were shot as fowlers and zero confirmation.

Fortunately, I was able to find the end of a rainbow and acquire 150 rounds of factory Lapua 6mm BR, more specifically, loaded 105 gr Scenar-L. This was a convenient find because I will be shooting that same bullet with my eventual hand loads, but that's a story for a different time. The first 100 rounds were fired in previous range trips to break in the barrel and collect some data.

For testing, I would use 5 high-quality muzzle brakes; three Area 419s - 6mm Hellfire, 6mm Hellfire Match, and 6.5mm Hellfire Match. Four and five were MDT's 6.5mm/.30 cal Elite Brake and 6mm Comp Brake.


Testing was pretty straightforward: shoot a 5-round control group with just a thread protector, then shoot a 5-round group with each of the brakes while monitoring velocity. The chronograph used was the Garmin Xero, the handiest piece of kit I own. Some of the things we are looking for are group size and shape, velocity, and point-of-impact shift.

Something to note before the test: the first 100 rounds were fired with the 6mm Hellfire Match. The largest group fired in the first 100 rounds was 0.999". 9 groups were fired in the previous range trip with an average group size of 0.674". The velocity data from those 45 rounds was as follows:

  • Avg - 2650.7 fps, SD - 13.3 fps, and ES - 58.7 fps.


  • The 6mm Hellfire had an 80% group size of 0.269". Those were shots 2-5; the 1st sailed almost an inch higher.

Now that we have the data, what can we do with it?

A few things stick out to me. First, a bare muzzle is the way to go if this were a benchrest or F-Class rifle. Next is all the brakes except the 6mm Hellfire, which had an average velocity in the area of 2650 fps with no POI shift. The only thing that would affect the speed like that is the length of the brake.

The POI shift could potentially be explained by the difference in weight of the brake, leading to some changes in harmonics.


Fortunately, the MDT Comp Brake produced the most well-rounded results, which is great because this was the brake I planned on using. In my experience, this brake has the best recoil reduction; I have been using it for the last 2 seasons. That is going to stay the same in 2024.

I'm aware that this is a small sample size of anecdotes. Due to a lack of ammo, I could only shoot 5-round groups; 10-round groups would be preferred. I will repeat this test later with a cartridge that can be more temperamental, like a .308 Winchester. Big picture, what can you do with this information? It's good to know that muzzle devices will affect your rifle. If you have multiple brakes, it's worth testing them to see which one your rifle likes.

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In 2018, William Maxwell fell into the rabbit hole of precision rifle shooting. He spends his free time competing, reloading, editing digital content, building rifles, and writing. He can be reached via Instagram @maddmaxxlop. 


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