6mm BR (Bench Rest)Remington and Norma
There is a lot of hoped for or imagined history related to the 22 BR and 6 BR cartridges. The short reality is somewhat different. At the time of the 22 PPC and 6mm PPC being developed by Ferris Pindell and Dr. Louis Palmisano (thus the PP), the bench rest winners were often the 222 Remington and the 6x47 Remington (the latter being a necked-up 222 Remington Magnum). The PPC team was made from reformed 220 Russian cases. The PPCs quickly replaced most any other rounds being used in bench rest competition.
Remington's Custom Shop was then being run by Mike Walker and Jim Stekl. I was in communication with them at the time, and still have a very early Light Varmint version of the 40XB-BR in 22 BR that they sent out with a factory test target that shows an average of 0.17 inches. Wooden stock and all. It's in my safe some 20 feet from where I write this.
Here's the deal... Remington was already manufacturing rifles for cartridges with three basic case head sizes; 223, 308, and belted magnum. In actual diameters, we're talking 0.378, 0.473, and 0.532 inches, respectively. The PPCs share a case head (essentially, extraction rim) diameter of 0.445 inches. Remington wasn't about to tool up for a new diameter of very limited sales potential. Therefore, in their development of short cartridges that would perform with the stability of the PPCs, Remington would simply have to use the standard 0.473-inch case head diameter. The development of short cartridges began with some special, small-primer-pocket 308 Winchester cases made by Remington just for this purpose. Shortened to about an inch and a half in length, and properly annealed, the boys went to work. The 308 case head, incidentally, is the same as the 22-250 on the small end and 35 Whelen on the fat end, with very many popular cartridges in between.
Remington began producing very nice small rifle primer 6 BR cases, and Jim Stekl went around showing a lot of people how to shoot consistent little match-winning groups. The cartridge, along with its companion 22 BR (formed from 6 BR cases), became very well accepted. In some camps, it was thought that the BRs might have a practical advantage over the PPCs in most outdoor matches because of their higher velocity, which helps when wind is a notable factor. I agree with this point. Especially at 200 and 300 yards, the flight time of the 6 BR over the 6 PPC is enough shorter to appreciably reduce the exposure time of the bullet to whatever breezes are present. It becomes increasing difficult to "dope" the wind as the distance increases; at least for me.
Not only was the 6 BR case neck reduced to 22 caliber, it was also opened up to 6.5mm and 7mm, primarily for silhouette competition. The latter eventually became a factory-supplied cartridge case, and with these cases available it was just a matter of time for it to be opened up to 30 caliber. The 30 BR, as it is called, is not as effective as the 7 BR for silhouettes because of the limitations of 30 caliber bullets being driven at rather modest velocities. Said differently, the 7mm bullets of similar weight cover the distance more efficiently and smack harder when they arrive.
Getting back on track with the 6 BR, keep in mind that the known development work came out of the Remington Custom Shop, inspired by the success of the PPC cartridges. Some accounts of its development may differ from this, so I welcome any documentable evidence that clearly shows otherwise. Here's where today's confusion starts to occur... Stekl at Remington saw the potential as a bench rest cartridge, which usually meant 100 to 300 yards. A 14-inch rifling twist would be about right for handling bullets suitable for those ranges, from as light as 55 grains to as heavy as 65 or so. To seat bullets averaging about 62 grains in weight, the throat of the chamber needs to be short enough for the seated bullet in a loaded case to contact or be just off of the rifling lands. That's where most bench rest shooters find their best success for match shooting with small-capacity cartridges. That process is not necessarily recommended for large-capacity cases or for some types of bullets, so readers must be cautious and understand that when a seated bullet is in contact with the rifling, a sharp increase in chamber pressure occurs during firing. Here's an example of being uninformed: I was at a public range, at a bench next to what I would describe as a hunting hotrodder, as he was blasting away with a Remington 700 BDL in 270 Winchester. A glance at his target through my spotting scope revealed a splattering of two-to-three-inch groups at 100 yards. These rifles are capable of excellent performance, so I thought I'd offer to take a look at his equipment. His frustration beat me to it, as he said, "I don't know what's the matter with this dang thing. It shot better with factory loads." Now that was a clue. In looking at his hand loads, I couldn't help but notice how far the bullet was seated out. And the fired rounds had mighty flat primers. When mentioning the obvious, he responded with, "A friend of mine that shoots competition told me to seat the bullet into the glands so the rifling marks would show up." Huh? What's that? The glands? This is the kind of thing that can happen when one shooter passes along some of their experience to another, without more information being laid on the table from both parties. Fast forward: I explained the process in greater detail, left him my phone number, and later that day received a call that the same loads seated to the recommendation of the loading manual were now shooting three shots in 1 1/4 to 1 1/2 inches. Some later tuning of the bedding, and getting the scope mounted dead plumb, reduced the group size average to right around an inch.
Well, it's this whole matter of rifle purpose and seating depth that now has us with two 6mm BRs to sort out. Norma apparently saw the round as having long-range potential, and gave its chamber a longer throat. Try to seat a long bullet into a Remington 6 BR chamber, and you'll run into rifling way before that "just contacting" point. Fact is, it won't chamber. Take a 6 BR cartridge loaded with a 60-grain flat-based bench rest bullet, and it will fall quite short of being able to contact the lands of a 6mm BR Norma chamber. It's this simple, or complicated... The 6mm BR is very flexible in that a great variety of bullet weights can be used with exceptional accuracy, from about 55 grains up to about 107 grains. Since the cartridge is almost exclusively used for competition from 100 through 1000 yards, bullets of that entire spectrum are used. The length of the throat is what allows the seating of the chosen range of bullet in a given rifle. If the rifle has a 12- or 14-inch twist, you're sure not going to be using long bullets even approaching the 100-grain or beyond range. They simply won't stabilize. And if your rifle is equipped with an 8-inch twist barrel, it better have a long enough throat to handle the long bullets, such as Sierra's wonderful 107-grain MatchKing. (Moly coated for me, thank you.) Using lighter bullets in a fast-twist, long-throated 6 BR means they are going to be spinning mighty fast (which tends to expose even the tiniest flaws), and will be taking a bit of a jump to contact the rifling.
What's best? It gets into that matter of choice. I like to send bullets on their way to targets in 1000-yard territory with greater velocity than can be had from the 6 BR, such as cartridges as speed-capable as the 6mm Remington Ackley Improved (6mm Rem AI), or David Tubb's relatively new and upcoming 6XC, which has already been proven superior to the 6 BR at long range. Also, I am not a fan of bench rest competition, as I don't enjoy the pace or the irritating noise coming from the firing line all day (worked in very noisy industry too long). So, for me, the 6 BR is an informal target round, great for introducing newcomers to shooting (they can shoot a 5-shot group through a penny postage stamp on their first try), and an excellent varmint round. I've had a variety of rifles chambered for it over the years, including three with 8-twist barrels. It's a fun long-range cartridge, being quite mild and all; but dead-still weather is important to its success, and that's hard to find in a lot of the country. I have retained three rifles in 6 BR; two 14-twist Remington 40-XBs, and an Ed Brown Compact Varmint single shot with a Shilen No. 8 barrel in 10 twist. The Remingtons are amazing out to 300 yards with light bullets, while a variety of Berger Bullets in the 80- to 90-grain range are spectacular in the Ed Brown.
So, then... If I was going to compete one more time in a bench rest shoot, what would I use? Heck, that's easy... I'm a dinosaur. It would be a 6x47 in a 14-twist 40-XB with a wood stock. Yeah, I already have it.