i read one article on it and it seemed to be a 6br grafted onto a 243 win case. It looked a lot like a 6slr. The article said its owner used unmodified 6br NECK die and seat. It did not mention resize die though. Any one have any experience loading for a br-k? Very interested in if you can resize it in br dies , well resize most of it anyway. Lol
6mm br-k any info?
- Thread starter Shawnba67
- Start date
swd
Silver $$ Contributor
Just think 6mm Competition Match with a 30deg shoulder instead of 32 or a super long 6 BRX.
I did a similar wildcat years ago but blew the shoulder forward a little. I use Forster shoulder bump BR dies and seater. It is very accurate and the BR dies held off work great. DTAC's at 3150 with N165. It would probably go a bit faster with H1000. It was back when I had to do my own wildcat...
Im going to do another one for a friend but Ackley style and have a slight crush at the neck shoulder junction. Pretty much what the BRK is, just my own specific dimensions.
I did a similar wildcat years ago but blew the shoulder forward a little. I use Forster shoulder bump BR dies and seater. It is very accurate and the BR dies held off work great. DTAC's at 3150 with N165. It would probably go a bit faster with H1000. It was back when I had to do my own wildcat...
Im going to do another one for a friend but Ackley style and have a slight crush at the neck shoulder junction. Pretty much what the BRK is, just my own specific dimensions.
SongdogHunter
Gold $$ Contributor
I have one and use a custom Hornady FL die
Larry Koch
Silver $$ Contributor
November 16th, 2007
Compared to a .243 Winchester, the 243 BR-K’s body length is about .006″ longer, and the shoulder is about .0055″ wider. The main difference is the shoulder angle (30° vs. 20°), and the location of the neck-shoulder junction (“NSJ”). Based on reamer prints, the base to NSJ dimension is 1.718″ on the 6BR Long, compared to 1.804″ for the .243 Winchester. Neck length is a bit shorter because “the neck shrinks a little when the shoulder blows out” according to Sosenko. We’ve provided a mock-up diagram of the 243 BR-K, but you should check with Dave Kiff of Pacific Tool & Gauge for exact dimensions. Dave created the reamers for both the 6mm and 22-caliber versions of this wildcat. Ask for the “22 BR-K” or “243 BR-K” reamer designs.
Wicked Velocity with Stable Brass
The main advantage of the 243 BR-K is serious velocity in a case that is very stable. Mike’s favorite load is the 95gr Berger VLD pushed by Reloader 22. With a stout load of RL22 and Federal 210m Primers, Sosenko is getting 3450 fps with the 95-grainer, with no bullet blow-ups. This is with a 1:8.5″ twist Broughton 5R barrel finished at 28.5″. The cases are holding up very well. Mike has a half-dozen loads on his brass and he hasn’t had to full-length size yet. Mike runs a .262″ tight neck, but there is also a no-turn version of the case (see illustration). Accuracy is excellent. Mike says the round delivers repeatable 1/4 MOA groups at 100 yards in testing. He has also experimented with N160, but, thus far, Reloader 22 has delivered smaller groups with better ES and SD.
VIEW 243 BR-K REAMER PRINT (No-Turn Neck)
John Adams shoots a no-turn (.274″) neck 243 BR-K with 105gr Berger VLDs. He’s getting about 3230 fps using Reloader 22. John says he can push the 105s faster, but 3220-3240 fps “seems to be the sweet spot.” John notes that “after about 5 reloadings on a case, it gets a little tight”. John then full-length sizes with a custom Hornady FL bushing die. “The Hornady custom shop dies work great” according to John. Adams also shoots a version of this wildcat necked down to 22-caliber. It has demonstrated outstanding velocity and good accuracy in initial testing with a 9-twist barrel. Using the 80gr Amax bullets, John is getting 3570+ fps speeds. John feels that his 22 BR-K needs some more development work. “The 243 BR-K is proven. We know what works. With the 22 I want to try different seating depths, experiment with a few different bullets, and fine-tune the velocity.”
243 BR-K in Competition
John Adams and Mike Sosenko developed the 243 BR-K Wildcat for use in monthly varmint silhouette matches at the Pala range in Southern California. Shooting prone with front rest (as in F-Class), participants engage metal targets at multiple distances out to 600 yards. It can get very windy at Pala, so you need a cartridge with great inherent accuracy, plus good wind-bucking ability. With its capacity to drive the .514 BC Berger 95s at 3450 fps, the 243 BR-K has what it takes to win at Pala. Shooting his 243 BR-K wildcat, Mike Sosenko has won many relays at Pala, and he is the only shooter to have shot a perfect 50 score, knocking down every target. Interestingly though, John tells us that “Mike’s five best scores this year, including his perfect 50, were shot using my guns with no-turn necks.”
How good are the ballistics for the 243 BR-K? Consider this… launched at 3450 fps, the 95 Bergers drift just 18.57″ in a 10 mph crosswind at 600 yards. By contrast, a 105gr Scenar shot from a standard 6BR at 2900 fps will drift 22.95″ at the same distance. The 243 BR-K exhibits nearly 20% LESS DRIFT at 600 yards–clearly enough to make the difference between a hit and a miss. (Ballistics calculated with Point Blank software for 70° temp, 1000 feet elevation, using manufacturers’ BCs.)
"243 BR-K" (6BR Long) Wildcat Delivers 3450 fps with 95gr VLDs
Gunsmith Mike Sosenko and long-time 6mmBR.com supporter John Adams have been using a modified .243 Winchester case with great success in California Varmint Silhouette matches. Officially called the “243 BR-K” (and informally dubbed the “6BR Long”), the wildcat is basically a .243 Winchester with less body taper and a 30-degree shoulder. The design essentially grafts a 6mmBR Norma “top end” to the .243 Winchester case. After fire-forming, Mike and John can reload this case using normal, unmodified 6BR neck-sizing and seater dies.Compared to a .243 Winchester, the 243 BR-K’s body length is about .006″ longer, and the shoulder is about .0055″ wider. The main difference is the shoulder angle (30° vs. 20°), and the location of the neck-shoulder junction (“NSJ”). Based on reamer prints, the base to NSJ dimension is 1.718″ on the 6BR Long, compared to 1.804″ for the .243 Winchester. Neck length is a bit shorter because “the neck shrinks a little when the shoulder blows out” according to Sosenko. We’ve provided a mock-up diagram of the 243 BR-K, but you should check with Dave Kiff of Pacific Tool & Gauge for exact dimensions. Dave created the reamers for both the 6mm and 22-caliber versions of this wildcat. Ask for the “22 BR-K” or “243 BR-K” reamer designs.
Wicked Velocity with Stable Brass
The main advantage of the 243 BR-K is serious velocity in a case that is very stable. Mike’s favorite load is the 95gr Berger VLD pushed by Reloader 22. With a stout load of RL22 and Federal 210m Primers, Sosenko is getting 3450 fps with the 95-grainer, with no bullet blow-ups. This is with a 1:8.5″ twist Broughton 5R barrel finished at 28.5″. The cases are holding up very well. Mike has a half-dozen loads on his brass and he hasn’t had to full-length size yet. Mike runs a .262″ tight neck, but there is also a no-turn version of the case (see illustration). Accuracy is excellent. Mike says the round delivers repeatable 1/4 MOA groups at 100 yards in testing. He has also experimented with N160, but, thus far, Reloader 22 has delivered smaller groups with better ES and SD.
VIEW 243 BR-K REAMER PRINT (No-Turn Neck)
John Adams shoots a no-turn (.274″) neck 243 BR-K with 105gr Berger VLDs. He’s getting about 3230 fps using Reloader 22. John says he can push the 105s faster, but 3220-3240 fps “seems to be the sweet spot.” John notes that “after about 5 reloadings on a case, it gets a little tight”. John then full-length sizes with a custom Hornady FL bushing die. “The Hornady custom shop dies work great” according to John. Adams also shoots a version of this wildcat necked down to 22-caliber. It has demonstrated outstanding velocity and good accuracy in initial testing with a 9-twist barrel. Using the 80gr Amax bullets, John is getting 3570+ fps speeds. John feels that his 22 BR-K needs some more development work. “The 243 BR-K is proven. We know what works. With the 22 I want to try different seating depths, experiment with a few different bullets, and fine-tune the velocity.”
243 BR-K in Competition
John Adams and Mike Sosenko developed the 243 BR-K Wildcat for use in monthly varmint silhouette matches at the Pala range in Southern California. Shooting prone with front rest (as in F-Class), participants engage metal targets at multiple distances out to 600 yards. It can get very windy at Pala, so you need a cartridge with great inherent accuracy, plus good wind-bucking ability. With its capacity to drive the .514 BC Berger 95s at 3450 fps, the 243 BR-K has what it takes to win at Pala. Shooting his 243 BR-K wildcat, Mike Sosenko has won many relays at Pala, and he is the only shooter to have shot a perfect 50 score, knocking down every target. Interestingly though, John tells us that “Mike’s five best scores this year, including his perfect 50, were shot using my guns with no-turn necks.”
How good are the ballistics for the 243 BR-K? Consider this… launched at 3450 fps, the 95 Bergers drift just 18.57″ in a 10 mph crosswind at 600 yards. By contrast, a 105gr Scenar shot from a standard 6BR at 2900 fps will drift 22.95″ at the same distance. The 243 BR-K exhibits nearly 20% LESS DRIFT at 600 yards–clearly enough to make the difference between a hit and a miss. (Ballistics calculated with Point Blank software for 70° temp, 1000 feet elevation, using manufacturers’ BCs.)
Larry Koch
Silver $$ Contributor
Just helping someone research.
I understand and good information . I just don't understand how some guys think I guess. Cartridges that stick around and win do so for a reason but some seem to like the unknown I suppose.
Larry Koch
Silver $$ Contributor
a little Fatter and shorter seems to be the direction of most mid to short range competition cartridges.
And the smokeless rifle powder improvements have much to do with it.
VA_XTC_Shooter
Silver $$ Contributor
Curious about barrel life comparison.
243 vs 243BRK
6BRX/6BRA vs 243BRK
Generally, one would expect more powder behind same bullet, increases velocity and decreases barrel life.
243 vs 243BRK
6BRX/6BRA vs 243BRK
Generally, one would expect more powder behind same bullet, increases velocity and decreases barrel life.
wildcatter
Silver $$ Contributor
The longer case neck should actually offset the more powder being burnt by reflecting the flame before blasting the throat. One nice feature of longer neck steep shouldered cases.
VA_XTC_Shooter
Silver $$ Contributor
That is my understanding as well, but we had a pretty thorough discussion not too long ago that there wasn't evidence to support that.
There is no way a BRX case will match a "243" case for speed with heavy bullets. With the same 105gr bullet that "243" case will have 200-250fps on the 6BRX case, in the real word that is a practical advantage especially when shooting steel
wildcatter
Silver $$ Contributor
One thing experience has shown me is much easier to control concentrisity in the longer throat. Especially when you run less freebore, we know that advantage.
Just some reasons I will always prefer a cartridge with a little longer neck. For me this would seem to be the benefit of this cartridge over some others.
As well as being able to load bullets with more neck support, and less freebore, without running out of enough powder capacity to make that 3050 to 3100 fps window we all know the 105 class bullets to perform their magic at. That does translate to longer barrel life, over those doing the same thing with shorter necks.
I will always believe in staying away from short necks for extended barrel life, for cases with equal performance.
That might be your experience but there is a reason some of us build big cased 6mms to shoot 105-115gr bullets allot faster then that. Not everyone in the world just sits and shoots BR
Pretty hard beating a .243 or .244 in the AI versions of you want more speed and very good accuracy. Good luck in your quest. The BR based cartridges have set lots of records for quite while with decent barrel life. I don't understand but then I am old and according to my wife , stubborn. It would be great if instead of an avatar or in addition too, your main shooting focus was shown. Long range, short range, ELR, Varmint Hunting, Big Game huntinting, Fclass , etc.
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