6mm vs 6.5mm

[savagedasher]

Ok, if you run the 243 at lower pressures. But if you run them at same pressure the 243 will be faster.

Why would someone want to under press a case . If you run the same pressure it should be the same speed. Why would someone want to burn 5 gr more powder and end up with less speed. Larry

 

[Nomad47]

Larry, I think you are putting too much faith in QL. I don't think anything based on the 6BR case can run with the .243.
My 6SLR, which is a .243 case (shoulder changed) with the same capacity, can push a 105 grain bullet at 3200 fps out of a 28" barrel - no pressure signs. Can a Dasher do that?

 

[savagedasher]

Larry, I think you are putting too much faith in QL. I don't think anything based on the 6BR case can run with the .243.
My 6SLR, which is a .243 case (shoulder changed) with the same capacity, can push a 105 grain bullet at 3200 fps out of a 28" barrel - no pressure signs. Can a Dasher do that?

No 3130 and still be under max pressure. The only way to increase speed is from more pressure. I'm not saying you don't have that much speed but your above max pressure. The ppc guys over press their case without having problems, no reason you can't. Larry
Larry

 

[Hoier]

Well I'm running a factory Remmy 243 varmint with 44.1 grs of powder it runs 2850. My 6br with a 28in Bartlein with 30.7 gr of Varget runs 2860. My old Dasher barrel ran at 3080. So I'd run a br family case. Why burn 14ish more grains for the same performance?

 

[savagedasher]

Well I'm running a factory Remmy 243 varmint with 44.1 grs of powder it runs 2850. My 6br with a 28in Bartlein with 30.7 gr of Varget runs 2860. My old Dasher barrel ran at 3080. So I'd run a br family case. Why burn 14ish more grains for the same performance?

My 6 dasher with a 29.5" barrel shoots 3105 with 105 . I have reloaded the cases 18 or more times with no loose primers. My pressures is 62700 on a 65000 psi case. Q L said I should
3108. Most of the time Q L is within 15 FPS. With Varget with in 30 FPS. but we all know that is common from lot to lot. Larry

 

[Hoier]

I was highly disappointed in the 243.

If you want pure accuracy the br family is the only way to.

Edit to add: I guess I shouldn't say that. I have a 6.5x47 that I just started shooting( like 20 rounds) but I also know if it was so much better more big name br shooters would be shooting them.

 

[savagedasher]

I was highly disappointed in the 243.

If you want pure accuracy the br family is the only way to.

I made a 6mm rem Ackley 6+47 hot. None of them shot any faster then the Dasher. And not nearly as accurate. The 6+ 47 hot shot so bad I figured the barrel was junk. Cut the chamber off and made it a dasher. It wasn't the barrel. Larry

 

[Erik Cortina]

This is so stupid it's laughable!

Any of you saying the Dasher will run faster than a .243 must be smoking some illegal substances.

 

[Hoier]

I'm telling you my 243 runs 2850 and from the cartridge page it's a little slow but not crazy. My straight 6br runs on the same level.

 

[Nomad47]

This is so stupid it's laughable!

Any of you saying the Dasher will run faster than a .243 must be smoking some illegal substances.

My sentiments exactly, Erik. Or maybe they live in Colorado - I think it will be legal there tomorrow.
Poor Colorado - used to be a great state. Now it looks like the Libs have over run it.

And Larry, I don't appreciate being called a liar. I said I had no pressure signs.

One more thing, Larry. Do you really think a 243 case will show the same pressure signs at 60,000 PSI that a Dasher case shows at 65,000 PSI?

 

[Nomad47]

I'm telling you my 243 runs 2850 and from the cartridge page it's a little slow but not crazy. My straight 6br runs on the same level.

Just because yours are the same does not mean everybody else's is the same. Identical barrels? Identical bullets? And powder?

 

[savagedasher]

This is so stupid it's laughable!

Any of you saying the Dasher will run faster than a .243 must be smoking some illegal substances.

Why don't you tell all of us how 243 with a max chamber pressure of ( 60190 ) psi will shoot faster the a dasher with (65000 ) psi. We need a good Laugh for 2014.
Happy New Year Larry

 

[Steve Blair]

Why don't you tell all of us how 243 with a max chamber pressure of ( 60190 ) psi will shoot faster the a dasher with (65000 ) psi. We need a good Laugh for 2014.
Happy New Year Larry

[br]
Because it is not just pressure. Cases with more capacity can use a greater volume of more progressive (slower) powders, causing more acceleration within the barrel. A lower pressure, sustained over a greater time period, can produce higher velocity. The 6BR variants run out of boiler room and that limits their ability to use more progressive powders.

 

[Hoier]

I do live in Colorado and know a little about shooting. So even if I do gain 200 fps with a 243(over my numbers), A Dasher is still a smarter choice. That is unless you like buying powder and barrels.

 

[Hoier]

And I think Larry runs 4350 in his Dasher.

 

[Nomad47]

I do live in Colorado and know a little about shooting. So even if I do gain 200 fps with a 243(over my numbers), A Dasher is still a smarter choice. That is unless you like buying powder and barrels.

I never said a Dasher wasn't a smarter choice. And it looks like you are now agreeing the 243 is faster than a Dasher.
BTW, I don't shoot a 243 - at least not a straight 243.

 

[Hoier]

Even if my 243 was 200fps faster than my current barrel it would still be slower than my Dasher. My 243 with a stout load of 4831 is only running 2850.

 

[Steve Blair]

And I think Larry runs 4350 in his Dasher.

[br]
A 30" barrel Dasher can certainly hit 3100 fps with H4350 and likely achieve full pressure, too. I hit 3400 fps with my 32" 6mm Remington using 105 Hybrids and IMR 7828 SSC, at full pressure. A greater volume of slower powder, if full pressure is achievable, will produce higher velocity. The only calculus is whether the gain is worth the cost in recoil, barrel life, greater powder cost, accuracy, etc. In many cases, it will not be worth it. In some, it might be what is needed. Everyone should do that kind of trade study and determine what is best for their application. Anything else is guessing.

 

[MarkS]

Matt asked what round to use for long range. My 6BRX will run as fast as a 243 with accurate loads, and past the speed with hot loads. I have DONE THAT and BEEN THERE, I had the hot 6mm, 243AI and 6AI, they will run higher speeds, BUT they will not come close the the accuracy of a 6BR IMP.

Matt asked for the best round for long range, he did not ask for the fastest. I am showing what works for me. You don't need the hot rods barrel burner to do it. And the VLD's do not like the go fast, I have tried it, they shoot best 3000f/s or less.

The 6br and 6BR IMP's will get the speeds because the case is MORE Efficient, the cases are full to the neck. The key to these rounds is the Lapua Brass, the 6br and 220 rus is the best brass made, not all Lapua brass is as good as the 6br. They like to run with hot loads, were most round don't. The 6BR IMP's owns 600yds benchrest and are kicking butt in 1000yds benchrest. Why is that?

Mark Schronce

 

[mikecr]

Improved cases are just that, a better design.
An Improved 6br, allows higher pressure powder burns as a work-around for many weaknesses in reloading.
It also has the right capacity(area) to springback from chamber, given sufficient barrel steel around it, and you can burn up faster powders -inside a bore of moderate(stiffer) length.
With this, it's easier to make shoot well, and for more stable reload cycles.

Running a non-improved cartridge of 243 volume at high pressures is heading for immediate limitations. You'll be beating the bolt open with a shoe..
To get case fill means means slower powders, at lower pressure burns. Then you get into barrel life, higher ES, and higher muzzle pressures at a given length of barrel.
If you measured H20 capacity variance between 6x reloaded 6Dasher -vs- 243Win, you would see what improving cartridges is really all about.
And with review of sustained distant shooting results, 6Dasher-vs- 243Win, you can see that capacity for accuracy(where desired) holds advantage over capacity for velocity.

Based on powders available, slightly underbore is easier to make shoot well than overbore.
A 6Dasher is perfect for ~105gr bullets.
A 6.5x47L is a great example of this for ~130gr bullets.
A 260AI, with more barrel steel around the chamber than common for the cartridge, could be underbore for ~140gr bullets.
I don't see 28cal and larger reaching this edge for 1kyd. They're just too big to run at very high pressure burns.