6.5 or 7

This might be worth a read for 6mm/1000 nay sayers... and with iron sights too!

http://[B]REMOVE[/B]accurateshooter.wordpress.com/2008/02/14/salazar-captures-az-1000-yard-title-with-6xc/



bingo1010 said:
am just getting into this long range thing and aml ookingfor opinions on what caliber first and secondly what cartridge. the 6.5 has obvious advantages for bc but so does the 7mm. i am not recoil sensitive so that isn't a concern for me. if you can call it that i have narrowed it down to 260, 6.5 x 284, 7-08, 284, 7 rem mag, and i will throw in the 300 win. i shoot 5 -600 yards regularly am now want to move out to 1000,...and possibly beyond.
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peter, thanks for the info.

I don't see the US manf changing their web designs or alloy anytime soon. Why bother?

The brass only has to survive at whatever the required SAAMI levels are - proof load levels, maybe a bit more????. That is for one, maybe two firings. ALL brass does this just fine, even Norma.

We just beat ours mercilessly for many many more firings :)

But as said by mpwolf, the benefits of the Lapua brass only come into play in an action/chamber combo that doesn't allow the brass to flow. Sloppy action/chambers will help any brass wear fast.

With tight set up and proper sizing, some brands like Win survive just fine.

Next concern is when will there be formal testing to ensure that these elevated pressures do not cause accelerated wear leading to action failure. I am sure that proof load pressure levels were never meant as operating pressures on any action.

Traditionally, there is enough slop in an action that brass gets fat and causes stiff bolt operation. Pretty clear signal to the reloader.

Now that we have super tight actions with super tough brass which cause zero brass growth even under proof load levels, where will the 'pop off valve' be?

Jerry

PS I have had the pleasure of shooting some Fed GM brass that was also extremely tough. Pity they made some bad lots and now gone byebye.
 
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i don't doubt the 6 mm is a contender but for an out of the box rifle they are not available with a fast enough twist barrel to work with the vld bullets, like it say in the link i think german had a 7.5 twist. when you drop down to a 100 - 105 bullet you sacrifice a lot ..no?where as the the factory offerings in 6.5, 7 and 30 have a twist to handle the longer bullets, at least that is what i see when pouring over all the info.
 
Not many people that shoot 1000 yards/meters seriously use factory barrels (for long anyway) because at that range, the shortcomings are far more than just twist rates; your point about factory twists rates however is quite valid.

You raise an interesting question about performance though..the difference in BC between a 115 Berger (.595)and a 105 Berger (.556) is actually very small. I have played with 105 Bergers all the way out to a mile and had amazing results. I have built a 6X47 Lapua (Ballistically so close to the XC it isn't funny) but I opted for a 1:8 to use 105's and 108's. I think the edge in speed will offset the difference in weight (I hope;))
 
Now that we have super tight actions with super tough brass which cause zero brass growth even under proof load levels, where will the 'pop off valve' be?

Hi Jerry
The primer is the only weak link remaining. You will have to watch them VERY closely and only much experience with a particular primer will tell you what is happening. Caution my friend.
 
Primers are no longer a reliable indicator of pressure. BR actions have the firing pin opening bushed and the bolt face is right on the primer so there is little room for the normal flattening and cratering.

As an excercise is superb machining and engineering, these actions are really at the top of the food chain. However, all the normal pressures signs are hidden or distorted. BR shooters routinely go WAY over magnum pressures.

How far over? Well, no one has bothered putting strain guage on to find out.

We know that historical wildcatters had loads that tickled 100,000psi. Yes, that is about DOUBLE the standard pressures in cases like the 30-06, 308 and 223.

No these loads were shot 'safely' with no serious pressure signs.

I have even seen some experimental handgun magnum loads that were approaching 120,000psi without locking up the revolver cylinders. That is pretty fancy engineering but way over safety limits.

The only way to measure pressure is with pressure monitoring equipment.

If you look up listed 6PPC 70gr loads in reloading manuals, you will find that velocities are much lower then what BR shooters routinely use.

There is only one way to get more speed in this case...one reason it is quite finicky to keep in tune.
Jerry
 
Jerry;

I agree with most of the above however the primers will flatten on high pressure loads and if you look closely there is some very slight cratering. As I mentioned you have to have much experience with a particular primer to read the cratering signs. Different primers indicate pressures differently, however the indicators are not as easily readable as they once were. I check the primer on every shot I fire.
 
Back to the original thread...

bingo1010, you refer to German S., so that rules out the 300 win mag, and LR hunting. The Aussies and the S. Africans like the 284, and the Americans like the 6.5x284. Both are very good, both can be argued about all day long. You pick.
 
is there any merit with the thinking of starting with the 7 08 then when the throat wears i can get it cut it to a 284? i guess i could do the same with the 260 then move up to a 6.5 284. while we are on the topic does anyone know where i can pick up a barrel for this build on short notice to be able to have it ready for spring. i already have a smith lined up but he has no barrels, and they are 6-8 weeks away. by the way i own a couple 300 mags and love em, just that for the long rangs thing i am told that recoil plays a huge factor in accuracy so that is why i have kind of shyed away from it, no matter what i build i want to put a brake on it similar to the holland quick discharge one that brownells sells. i like the look of the 3 chamber design, plus there is no dirt and crap being kicked up like a traditional design. if i could find a scaled down version of a 50 bmg brake i would go for that.
 
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You might be further ahead to just cut an inch or so off the barrel and have it rechambered the same caliber. A new 6.5-.284 barrel will stay competitive to 1500 rounds if you are lucky. I don't think you will get another 1500 out of it if you switched calibers.
I would also check the rules for muzzle brakes for the type of shooting you want to do. Brakes are not allowed in some competitions.
 
Is a 6.5x284 truly a SA round? If you were wanting to use the magazine of a SA Remington, you'd be limited to about 2.80" cartrideg OAL.
 
i have been told the 6.5 x 284 should be built on a long action. it will fit in the box of a sa, but the only thing being that you cannot extract a loaded cartridge without pulling the bolt. i have decieded to go with 7 mm and found a barrel... thanks Ian for the krieger.....next is the chamber. i am leaning to 7 -08, but also considering a "normal" 284. if i do build a 7-08 is there any reason that i can't put it in a long action? being a remington action it should feed correctly..no?, is there any reason why a guy shouldn't use a long action for a short action cartridge?
 
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