Frequently Asked Questions
What is the 6mm BR?
The 6mm BR that is most commonly used today is also called 6mm Norma BR, "6BR Norma", or just plain "6BR". Norma started with the 6mm Remington Benchrest case and made the neck longer and increased the base dimension slightly. Though Norma standardized the round, most people shoot Lapua brass, because of its superior quality and uniformity, not to mention lower cost. The case capacity of Lapua brass is about 38-39.5 grains of H20, after fire-forming. The exact capacity depends on your gun's chamber and the brass lot.
What Kind of Accuracy Can I Expect?
The 6mm BR is one of the most accurate cartridges in existence, bettered only by the 6 PPC and 22 PPC. A well-built rifle with a match-grade barrel should deliver consistent 5-shot groups in the 2s at 100 yards with flat-based bullets. If you get lucky, perhaps it will group in the 1s. European shooters firing Norma 6mm BR loaded ammo in Sauer factory target guns report .3 moa accuracy at 300m. 600-yard match shooters are getting sub 3" aggregates in real world conditions, shooting 100gr bullets in 1:8 twist barrels.
Which is Better -- 6mm BR or 6PPC?
Both are extremely accurate and efficient cartridges. The 6BR shares the short/fat case design and small primer hole that make the 6PPC so accurate. In 100-200yd benchrest competition, the 6PPC is still the "winningest" cartridge around. However, the 6mm BR is superior at 300m and beyond. With more case capacity, the 6mm BR can drive the heavier, higher BC bullets needed at long distance. With the 6PPC you have to turn necks and fire-form the cases from smaller 220 Russian brass. That's lots of work. Conversely, Lapua 6BR brass shoots great right out of the box. Bottom line: the 6PPC may be a tiny bit more accurate at short ranges, but the 6mm BR is easier to load and shoot, and is incredibly accurate all the way out to 1000 yards. In fact, the current ten-shot 1000yd world record was set with a 6mm BR.
What Brass Should I Use?
Use Lapua brass. None better. Make sure your gunsmith chambers for the Lapua brass dimensions, not 6mm BR Remington brass or Norma brass. Some lots of the Lapua are very slightly larger at the base than Norma. If you have a barrel tightly chambered for Norma brand brass, Lapua brass should fit if you use a small base size die. The tight spot is at the web of the case--it may be just a tiny bit larger diameter than the Norma. But the Norma brass is very good. It's just a good deal more expensive than Lapua from most vendors. Current lots of Lapua 6BR brass measure .2685"-.269" neck diameter with a bullet seated and .469" right at the web of an unfired case. We've seen some of the Lapua brass has a bit of a flare right at the mouth which means that a .271" neck might be too tight. Setting the neck for .272" is a pretty safe bet for current lots of Lapua brass. Here is Lapua's current specification:
What Size are Lapua 6BR Flash-Holes and Should I Ream Them Larger?
When Lapua started making 6mm BR Norma brass ten years ago, Lapua adopted a 1.50mm (0.059") flash hole size. However, Lapua tells us that production tolerances run up to 1.60mm (.063"). OK, should you ream your flash-holes to fit a standard 1/16" (.0625") decapping rod? We suggest NOT reaming. First you have to buy special tools, and you may end up with flash-holes that are bigger than you want. If you use the K&M PPC flash hole deburrer to ream the hole (from the inside) it will end up about 0.068". If you use the Sinclair 07-3000 tool (which reams from the outside), shown below, the flash-hole will end up about 0.063". The later is probably OK, but when you start to approach 0.070" we think you may be losing some of the claimed accuracy advantage of the small PPC-style flash-hole.
If you want to leave your 6BR flash-holes at minimum diameter, turn down your 1/16" decapping pins or decap with a Redding or Harrell's die. The 6BR and 6PPC Redding and Harrell's dies normally ship with a .057" diameter decapping pin. (If yours is larger, ask Redding for the smaller version.) The .057" decapper will work with UN-REAMED 6BR brass. So, to make a long story short, flash holes anywhere from .059"-.063" are "normal" and a Redding die should work. But if you want to use a 1/16" (.0625") decapping pin (found on most "universal" decapping dies) you should ream with the Sinclair 07-3000 tool. UPDATE: Recent lots of Lapua 6mmBR brass have shown a little sliver of brass that can occlude the flash-hole. You will want to remove this excess brass so that the flash-hhole is clear. You can do this with an inexpensive "pin-vise" and #53 (.0595") drill bit.
What is the Correct OAL for the Case?
New Lapua brass measures 1.556-1.557". SAAMI spec for the 6mm BR Norma case is 1.560". By contrast the OAL spec for 6mm BR Remington is 1.520". The Lapua brass is headstamped 6mm BR Norma-Lapua. We trim all our cases to 1.555" when any one reaches 1.560" or longer.
What Barrel Twist Do I Need?
The most versatile barrel is a 1:8 twist, from 26" - 28". This will shoot everything from 65gr FB bullets to 107 VLDs with great accuracy. For shooting out to 600 yards, in calm conditions, you may get best accuracy with custom 80-90gr FB bullets. These work best in a 1:12 twist tube. So far, the 1:10 twist has been a "tweener" that hasn't been as popular as a 1:8 or 1:12. On paper, the 1:10 should do well with the new low-drag FB bullets, and most 90gr boat-tails. The 95gr Berger VLD requires at least a true 1:9. But right now, when most people buy their first 6mm BR barrel, they chose a 1:8.
Tight Neck or No-Turn Neck -- What's Best?
The collective wisdom is evolving on this issue. Originally, 6BR shooters emulated what works for the 6PPC--tight .262" necks with a .009" or so neck wall thickness. Now the trend is in the other direction. Many shooters have had great success with .268-.269" necks that allow full neck uniforming with a cut up into the shoulder to block the formation of doughnuts. That said, we are now seeing very accurate rifles being built with .271-.272" and even .274" chambers that allow Lapua 6mm BR brass to be loaded and shot with no neck-turning. The results have been encouraging to say the least. Richard Schatz recently set a 1000-yard world record with a .271"-necked 6mm Dasher. And there is evidence that the longer VLD bullets work best with the greater neck tension allowed by unturned or minimally-turned brass. One well-known shooter says he has seen no loss of accuracy since changing to no-turn necks, and that's how he will chamber all his future barrels. However, most top smiths still recommend turning necks, but not down to .262". A .269" chamber appears to be a good compromise, allowing a quick, easy one-pass turn without sacrificing beneficial neck tension. For a varmint or tactical rifle, the choice is clear, however--go with a no-turn neck so you can spend more time shooting and less time reloading. Both the Lapua and the Norma brass are good enough that you will give up very little accuracy.
What Is Recoil Like on a 6BR?
Recoil is mild. A 17-lb 6BR recoils less than a standard 9-lb AR15. Compared to a .308 rifle of equal weight, the 6BR has 55% less recoil, and the 6BR's movement is much less snappy. By the numbers, a 17-lb 6BR rifle shooting a 100gr bullet at 2950 fps recoils at 3.74 fps, with 3.7 ft/lbs of recoil force. By contrast, a 17-lb .308, shooting a 168gr SMK at 2700 fps, recoils at 5.59 fps, with 8.25 ft/lbs of recoil force.
Does Anybody Sell Factory-Loaded Ammo?
Yes, both Lapua and Norma sell extremely high-quality 6mm BR loaded ammunition. This is super-premium stuff, made for 300m competition. Lapua offers a 77gr HP round, plus 90gr and 105gr cartridges loaded with Scenar BTs, either moly or naked. Norma offers one product--the 6mm BR Diamond Line, loaded with a 105gr moly-coated Berger bullet. Full review.
Can I Buy a Production Rifle Chambered in 6mm BR?
Very few factory rifles are available in the United States chambered in 6mm BR, either the old 6mm Remington BR version, or the newer version we call 6mm Norma BR. This is because the shooters who want 6BRs are looking for a level of accuracy and quality that just can't be had with factory barrels and mass-production assembly techniques. Blaser does offer a single-shot version of its straight-pull target rifle in 6mm Norma BR, and Sig-Sauer offers 6mm Norma BR single-shots in their European-market target rifles. These are not currently being imported into the United States, however. Among limited-production American-made guns, the Cooper Arms Model 22, the Remington 40XB (Custom Shop), and the Tubb 2000 are all available in a 6mm BR chambering.
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