Reply with quote #1
I have been following your forum for some time and appreciate the knowledge of most of you guys. please enlighten me with a bit more. why is a 6br. case superior at long range paper shooting, 600 t0 1000 yds, than my .243 winchester. it has been mentioned that the 6br case is more efficient. what makes it so and really how big of a difference is there.
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Rich, Here are 2 differences that make alot of this happen:
- 6BR case capacity is around 37-gr of water
- .243 capacity is around 54-gr of water
- 6BR Shoulder Angle = 30-deg.
- .243 Shoulder Angle = 20-deg.
The 30-deg. shoulder provides a more ideal turbulence pattern for consistent powder ignition over the 20-deg. A 40-deg. shoulders that go with Improved .243's & 6BR's are better yet.
The less case capacity improves load density, and is a big factor. One of the biggest things is that the VLD/Match-King type bullets ballistic coefficients and areodynamics are so good now days, that they don't need to be horsepowered with alot of velocity. They just need to be above Mach 1.15 (supersonic) at 1000yds to stay stabalized. The Sg factor of these type bullets seem to stay good in the 2700 to 3100-fps (muzzle velocity) range.
I am going to be doing some 1320-yd(3/4-mi.) testing in the near future with Lapua 105's and a 6-Dasher. This distance will put the bullets in transonic range of speed with my pet loads.
This testing should give me some great data on Sg (stabality). If they perform at this distance, I will then go out in the subsonic area of 1-mile and test them more. When I get these testings complete, I will post here on 6BR.com my findings/data from these testings.
Being a big fan of the .243, my personal reasons for liking the 6BR family some what more besides the obviuous ones given above is:
- Barrel Life
- Less Powder (cheaper reloading expense)
But for hunting, I will take the .243 over the 6BR any day. Here I like the extra horsepower!!!!
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There's a thread running on this right now on Benchrest.com, in the "Hybrid Rifle" section. The most interesting post is from AlinWA who sometimes posts here as well. But to save you a couple of clicks, here's what AlinWA says:
"...6BR all the way, NO DOWNSIDE!!!!!
The BR will run within 100fps or even BEAT the .243 for velocity and flatout run rings around it ever'where else. (Except with 80-95gr bullets, here the .243 has a slight velocity edge). Short version, 10yrs ago I set out to prove that the .243 case would shoot with the best of them. I spent many thousands of dollars...
I ended up using the .243AI version: 4 trued 700's, 2 Time Precision, 2 Nesika--Full-Blown BR stuff. Myself and 2 friends have used 5 different .243AI reamers, 15 different barrels in all twists (Lilja, Shilen, Krieger, etc) I've had .243AI barrels built for proven 6PPC guns, in fact I've had 3 different setups that were purpose-built BR guns but for them I've fitted .243AI and 6BR barrels JUST to test them head to head against their 6PPC barrels.
I've 3 times cut down barrels from .243AI, and RECHAMBERED THE USED BARREL for 6BR, each time was same-same--6BR wins. One of these, a Shilen 14" twister had 2470 hotrodded .243AI rounds through it and I talked my local 'smith into scabbing a 6BR chamber into it--he didn't even want to stick his pilots into it, but I wanted a spare fireforming barrel for one of my 6BR chambers that didn't fit the others in my lineup. It now shoots better than it ever has, by FAR, in fact it shoots WELL!.
The secret to getting the performance out of the 6BR is in the loading dies. It works BECAUSE YOU RUN IT AT HIGHER PRESSURE than a .243 is capable of. A 6BR case will take more pressure than a .243 case. To utilize this feature you must FL size every loading but NOT with factory dies, dies must be custom-made to fit your chamber[.]"
Link: 243 vs. 6BR thread
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Giving some rebuttal to the post above. On the part that reads:
"The BR will run within 100fps or even BEAT the .243 for velocity"
One of my .243win Pet Loads moves VLD's in the 3400f/s area.
In my 6-Dasher, 3125f/s is the fastest velocity that I have ever gotten, and it showed pressure signs besides, and did not shoot good. 2975 to 3050f/s is where I get my best results with the Dasher.
In the .243win, 3300 to 3400f/s is where I got best results with the same VLD bullets with + 3400f/s capability.
So to my findings, there is + 300f/s difference.
-[ These are just my reloading findings! ]-
But I also find the 6-BR family to have better accuracey then the .243 family. And as said in my other post here: "for hunting, I will take the .243 over the 6BR any day. Here I like the extra horsepower!!"
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ok, i think i understand the fact that the 6br is more accurate for the afforementioned reasons, but how much more accurate. are we talking a difference of 10 inches in group size at 1000 yards or 2 inches. if its a windy day will the extra hp equalize the group size somewhat. up here in the geat white north we shoot for score not group size. thanks
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From my own guns here: 243win vs. 6-Dasher. At 1000yds, the 6Dasher would out group my 243's on a average of at least 6". Night and day difference.
My 6-Dasher is a new gun I had built this fall. I have
fired the fallowing groups and averages with it:
- 1000 Yards -
20 - 5-Shot Groups = 8.705" Average / .8705-MOA
3 - 10-Shot Groups = 10.025" Average / 1.002-MOA
[ 28" Shilen / 1:8 Twist / .271 Neck / .200" Free-Bore ]
[ Pet Load = 33.5gr N-140 / 105-Lapua / CCi-450 / 3050f/s ]