6mm BR Norma Revisited - Inside MDT

A few years ago, I built a 6BR Norma with a Tikka action and an MDT ESS Chassis System. The rifle was treated mostly as a range toy and a way to familiarize myself with the cartridge. This was when BR mags weren’t quite a thing yet, and everyone was moving towards the 6 Dasher or 6 GT. Fast forward to this past Winter, and I’ve once again decided what’s old is new. There have been a few technological advancements that made me think it was worth giving 6BR another look.

More: Analysis: 6MM BR NORMA

The biggest issue 6BR had with magazine-fed bolt actions was feeding failures. Since the cartridge is so short, when it exited the magazine, it could run right into the shoulder of the barrel, causing a malfunction. Using the new MDT 6 BR magazines with the adjustable mag catch and magwell in the ACC ELITE should, in theory, fix that. Spoiler alert- it did.

BUILDING A 6BR NORMA

The idea was to spin up a barrel for my competition rig and shoot some matches. The components of this rifle are as follows:

• Action -Curtis Custom Valor
• Trigger -Trigger Tech Diamond
• Barrel -International Barrels 6mm 1:7.5” twist, 6BR Manson Reamer
• Brake -MDT 6mm Comp Brake
• Chassis -MDT ACC ELITE
• Optic -Tract Toric ELR 4.5-30x
• Accessories - MDT weights, Ckye Pod, Controls Bridge, NV Bridge

TESTING 6MM BR FACTORY AMMUNITION

Fortunately, I procured three boxes of Lapua factory 6mm BR Norma with 105 gr Scenar-L bullets. Coincidentally, I will be doing my hand loads with that same bullet. That gives me a strong baseline to build off of.

I broke the barrel in over several trips, shooting one 50-round box of ammo per trip. Velocities and group sizes were tracked the entire time. These range trips served a dual purpose as the brass was being fired to the chamber along the way. Here are the results from the first two trips:

First trip: 40 rounds clocked

• Avg Vel - 2638
• SD - 13.6
• ES - 70.2
• Avg group size - 0.777”

Second trip: 45 rounds clocked

• Avg Vel - 2650.7
• SD - 13.3
• ES - 58.7
• Avg Group size - 0.674”

Note: the barrel was fully clean in between each trip.

The third and final break-in trip ended up being a muzzle brake test that you can read more about here.

More: Do Muzzle Brakes Affect Group Size?

LOADING THE 6MM BR NORMA

Disclosure: This article is for informational purposes only; all load data is for my rifle specifically. Before loading your ammo, reference published load data from bullet and powder manufacturers.

All cartridges were loaded with once-fired Lapua brass, Lapua 105-grain Scenar-L bullets, Varget, and CCI BR-4 primers.

• After reading some forums and checking out the Precision Rifle Blog, I decided that with the 105-grain bullet, my target velocity would be somewhere between 2750 and 2800 fps. If you believe the BR forums, 30.0 grains of Varget should get you where you want.
• I used to get deep in the weeds with measuring bullet jump to the lands, which turns into a rabbit hole. While I’m sure you could grind out a few hundredths of an inch by playing with bullet jump, anecdotally, it is not worth the hassle. The factory ammo measured 2.300”, so I decided to go with 2.325”.
• I did a straightforward OCW test shooting charge weights from 29.4 through 30.2.
• The results were pretty pleasing: the groups ranged from 0.551” to 0.786” with velocities ranging from 2746 to 2829; all SDs were below 8 fps.
• On the second trip, I tried charge weights from 28.8 to 29.2 with similar results; groups from 0.597” to 0.956” and velocities from 2712 - 2750, all SDs below 9 fps.

I decided 29.4 grains was my match load. My 3rd trip to the range, I decided I was going to shoot 60 rounds on paper and through the chronograph to get solid data and refine the zero as best as I could. The results were extremely pleasing.

• Avg Vel - 2776
• SD - 7.3
• ES - 29.3
• Average group size - 0.699” (5 out of 12 were 1/2 MOA or better)

Something to note: all groups were shot consecutively, and the only cool-down period was when loading the magazines. After 300 rounds were down the pipe, a match quality load was locked down. That was good timing because the following weekend was my opening match for the year.

PROVING GROUNDS: PRS COMPETITION

It’s safe to say after nine stages and 104 rounds fired for the day, any misses were not the rifle or ammo’s fault. It was a typical upper mid-pack day for me; 2/18 impacts on the last two stages certainly did not help, but that’s how the cookie crumbles sometimes.

The MDT BR mags and ACC Elite’s adjustable magwell did their job. The only feeding issue I had was when I put too much pressure on the magazine, causing the rounds to nosedive into the face of the barrel. Out of 404 rounds, I had five feeding issues that were rectified when I tightened up the mag catch.

A few other competitors who switched back to BR from the GT have told me that using an action with a bolt-nose recess also helps with feeding. The recess acts as a pseudo-feed ramp. It might be worth checking out if you’re willing to sacrifice a 60° bolt throw for that.

CLOSING THOUGHTS

It’s safe to say that in 2024, 6mm BR Norma is still a viable option in the PRS space. A lot of people are moving on to .25 caliber cartridges, but I’m not there yet. To me, the inherent precision of the BR with the minimal recoil makes it the ideal PRS cartridge. That being said, I will be revisiting 6.5x47 Lapua next.

6MM ARTICLES FROM MDT

• Building a 6mm GT for Competition
• ANALYSIS: 6MM BR NORMA
• HORNADY 6MM ARC FOR COMPETITION
• 6mm GT Load Development
• LOADING 6MM ARC AND .223 REMINGTON WITH A DILLON PROGRESSIVE PRESS
• Ultimate Reloader: 6mm ARC and MDT TIMBR Frontier Rifle Stock
• MDT RELEASES 6BR AICS MAGAZINES
• MDT Mention - Ultimate Reloader 6GT Precision: From Reloading to 1000 Yards
• Analysis: 6.5x47 and 6x47 Lapua

ABOUT THE AUTHOR

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.