Port Angle vs. Recoil with Hawkins Brakes

How much does muzzle brake diameter actually matter? Do angled ports really reduce more recoil than straight ports? In this video, we put both theories to the test using our advanced recoil rig to compare the Hawkins Precision Tank ST and Backdraft muzzle brakes across both 6.5 Creedmoor and 300 Win Mag platforms. The results revealed some surprising patterns — including measurable differences between brake diameter and port angle that became dramatically more apparent with magnum cartridges. If you’ve ever wondered what truly affects recoil reduction and how much of it you can actually feel behind the rifle, this is a test you won’t want to miss.

Disclaimer

Ultimate Reloader LLC / Making with Metal Disclaimer: (by reading this article and/or watching video content you accept these terms). The content on this website (including videos, articles, ammunition reloading data, technical articles, gunsmithing and other information) is for demonstration purposes only. Do not attempt any of the processes or procedures shown or described on this website. All gunsmithing procedures should be carried out by a qualified and licensed gunsmith at their own risk. Do not attempt to repair or modify any firearms based on information on this website. Ultimate Reloader, LLC and Making With Metal can not be held liable for property or personal damage due to viewers/readers of this website performing activities, procedures, techniques, or practices described in whole or part on this website. By accepting these terms, you agree that you alone are solely responsible for your own safety and property as it pertains to activities, procedures, techniques, or practices described in whole or part on this website.

Hawkins Tank ST vs. Backdraft

We’ve previously tested both the Hawkins Precision Tank and Updraft brakes, but this time we directly investigated the relationship between port angle and recoil as well as brake diameter and recoil.

Hawkins Precision’s Tank ST family of brakes has four straight ports 90 degrees from the bore axis.

These are designed to direct more gas towards the side of the rifle and less towards the shooter, reducing concussive blast. This self-timing brake is available in four different calibers (6mm, 6.5mm, 7mm, and .30) and three different diameters (0.990”, 0.875”, and 0.750”). Each of these brakes has a ⅜” hex port for installation and a jam nut with set screw that allows for easy brake removal without the need to retime.

Hawkins’ newest self-timing muzzle brake, the 4-port Backdraft, uses angled ports to send more gas to the rear, further reducing recoil. It shares the same ⅜” hex port, caliber, and diameter options as the Tank ST.

In general, running an oversized brake for your caliber doesn’t matter as bullet clearance in a brake has a very minor effect on recoil reduction. We demonstrated this with our recoil rig.

Bullet clearance, however, does have an effect on noise reduction with suppressors.

Recoil Rig Testing and Results

Our recoil rig, based off of a design from Cal Zant from the Precision Rifle Blog, measures forces at the buttstock at up to 200,000 samples per second. It utilizes the DEWEsoft Sirius 8-Channel DAC and a PCB Piezoelectronics load cell to capture directly comparable results. We’ve used it to conduct a variety of tests, including reduced loads, rifle weight-vs-recoil, and more.

For these tests, we used two different rifles — a 6.5 Creedmoor and a 300 Win Mag.

My 6.5 Creedmoor PRS build with heavy Foundation stock and robust recoil pad greatly contrasted my lightweight, factory Bergara 300 Win Mag with a softer pad. Many factors affect recoil, including rifle weight, pad style, powder burn rate, and the human body! The recoil rig allows for directly comparable results for a particular rifle/cartridge combination.

For this test, I shot each rifle bare muzzle, with two different diameter Tank ST brakes and with two different diameter Backdraft brakes.

The 6.5 Creedmoor with Berger 140-Grain factory ammunition had extremely close, consistent results with peak force reduction ranging from 31.79% to 37.53%.

Running any of these brakes on a 6.5 Creedmoor is approximately equivalent, but I did note that the medium Backdraft brake and the large Tank ST brake had nearly the same effect on recoil. This means that shooters can achieve about the same recoil reduction with their preferred port style.

The large Tank ST brake is bigger and heavier, whereas the medium Backdraft brake directs more gas towards the shooter. I also noted that the large Tank ST cut recoil 6% more than the small Tank ST did and that the Backdraft small was 3% more effective than the small Tank ST.

As I expected, we observed larger differences with the 300 Win Mag and Hornady 178-Grain ELD-M factory ammunition.

Peak force reduction ranged from 60.12% to 70.49% compared to the bare muzzle, with about 10% difference between the most and least effective braked configuration. The large Tank ST had a 0.24% greater recoil reduction than the medium. This is very similar to what we observed with the same brakes and the 6.5 Creedmoor. They are essentially equivalent. The medium Backdraft brake cut approximately 9% more recoil than the small Backdraft and the large Tank ST cut 10% more recoil than its small equivalent. Magnum cartridges always have greatly-exaggerated differences on the recoil rig compared to smaller cartridges. The 300 Win Mag has increased gas velocity, which equates to greater force reduction. The softer buttpad on the 300 Win Mag also doubled the time interval of the test: 20ms compared to 10ms with the 6.5 Creedmoor.

Conclusion

For the 6.5 Creedmoor class of cartridges, the diameter of the brake can make an approximate 6% difference in recoil reduction.

The angled ports made even less of a difference – approximately 3% with the 6.5 Creedmoor and 1% with the 300 Win Mag. Brake diameter has a much larger effect on recoil reduction with magnum cartridges.