260 improved brass choices

[10X]

just chucked out all the junk(case head too soft) hornady brass I was using and now its time to move up to lapua
There is .260 lapua brass available why make .260 imp from .243 brass?
It seems that most of the articles I can find online the shooter made the cases from fire forming 243 brass or 7-08 brass.I have not found 1 article where they started out with a .260 case.
So before I order 100 cases I ask what is the best way to get nice lapua 260 imp cases
.243?
.260?
7-08?

thanks

 

[Santiam338]

Go with the 260 Lapua brass and don't look back..I run my 260 Ack 2950 with 140 Bergers..A fairly hot load and am on 7 firings with no signs of wearing out.. The smith that built my gun thought I would probably have to rebarrel before I wore my 100 brass out..We shall see..LOL

Good luck

 

[Mikecr]

You'll find a lot of off-cal forming history with 260AI because until recently there was not good 260 brass. Truly the 260AI had been dismissed long ago because of this.
I expected a mass shift back to 260AI when Lapua offered 260 brass, but trends move faster towards new than old.
Anyway, it would make no sense to use anything but lapua 260 brass for this today.

 

[scottishkat]

Midway has Lapua 260 rem brass on sale now.

 

[stomp442]

The reason you have seen so many articles using other cases to form the Ackley case is because at the time of writing the Lapua stuff didn't exist yet. Personally, I think the .260 Ackley is worth the work even if you had to use different brass to start with. I am also getting great velocity and case life out of my Lapua cases, 2940 fps and at least 7-8 reloads on them now.

 

[ramrod79]

You guys that are running the 260 Improved are they in short or LA rifles. I am looking at switching up from my 6.5 284 but want a short action and the 260 AI looks to keep up with the 6.5 284 with out eating barrels .

 

[Mikecr]

I'll suggest a long -magnum diameter action.
The reason is bullet lengths from the best in 26cal leads to relatively long COAL. And to run beneficially higher pressures(faster powder), you'll need more barrel steel around the chamber than a standard SA allows. Go tighter clearances than SAAMI.
The 260AI will better anything of value from a 6.5x284, and best it in every reloading category. It's a better cartridge as it's the perfect capacity for ~140gr bullets. Not excess, not deficient, perfect. It is also greatly improved over the 284 case design.
Better barrel life, longer lasting brass, and if you believe faster powder higher peak pressure for given MV usually equals better accuracy, you're right, it usually does.

 

[stomp442]

Big plus one to that. Mine is built on a Savage long action simply so I can change to a long action caliber in the future if I so choose.

 

[Nomosendero]

I'll suggest a long -magnum diameter action.
The reason is bullet lengths from the best in 26cal leads to relatively long COAL. And to run beneficially higher pressures(faster powder), you'll need more barrel steel around the chamber than a standard SA allows. Go tighter clearances than SAAMI.
The 260AI will better anything of value from a 6.5x284, and best it in every reloading category. It's a better cartridge as it's the perfect capacity for ~140gr bullets. Not excess, not deficient, perfect. It is also greatly improved over the 284 case design.
Better barrel life, longer lasting brass, and if you believe faster powder higher peak pressure for given MV usually equals better accuracy, you're right, it usually does.

"the 260AI will better anything of value" Are you in reference to efficiency? If both are built on a long action and with 140's, looks like maybe 100fps difference at equal pressures, is that correct or is it less?

 

[Mikecr]

"the 260AI will better anything of value" Are you in reference to efficiency? If both are built on a long action and with 140's, looks like maybe 100fps difference at equal pressures, is that correct or is it less?

Action length -vs- cartridge length merely leads to your ability to load and eject loaded rounds.

The big differences in potential are seen with the best capacity for intended bullets in the lowest chamber area possible. Best capacity is of course tied to fastest viable powders available suiting intended bullet weight, and historical evidence of accurate muzzle velocity range -over a barrel length range.
Magnum diameter barrel tenons provide more barrel steel around a chamber area than smaller diameter tenons. Combine this with tighter lower body clearances, and a case expands less on firing, ideally below yielding to difficult extraction.

With this, you can run higher pressure, which is a work-around for internal ballistic variances.
Once peak pressures delve into diminished returns(mv-wise), all the smaller factors affecting barrel time become way smaller.
This is the foundation of the most accurate cartridge designs today, each beginning with a bullet and giving/taking within real limitations.

A good example is the 6.5x47L and ~130gr bullets for 600yd shooting.
It's smaller than either 260AI or 6.5x284, and cannot push ~140gr bullets anywhere near. However, this is not a problem to 600yds, and the 6.5x47L can push ~130gr bullets to as much in accuracy potential as the bigger cartridges -more consistently, and with many other advantages over the bigger cartridges.
The 260AI and ~140gr bullets for 1kyd shooting extends similar advantage over the larger 6.5x284, AND the smaller 6.5x47L (overall).

 

[Nomosendero]

Action length -vs- cartridge length merely leads to your ability to load and eject loaded rounds.

The big differences in potential are seen with the best capacity for intended bullets in the lowest chamber area possible. Best capacity is of course tied to fastest viable powders available suiting intended bullet weight, and historical evidence of accurate muzzle velocity range -over a barrel length range.
Magnum diameter barrel tenons provide more barrel steel around a chamber area than smaller diameter tenons. Combine this with tighter lower body clearances, and a case expands less on firing, ideally below yielding to difficult extraction.

With this, you can run higher pressure, which is a work-around for internal ballistic variances.
Once peak pressures delve into diminished returns(mv-wise), all the smaller factors affecting barrel time become way smaller.
This is the foundation of the most accurate cartridge designs today, each beginning with a bullet and giving/taking within real limitations.

A good example is the 6.5x47L and ~130gr bullets for 600yd shooting.
It's smaller than either 260AI or 6.5x284, and cannot push ~140gr bullets anywhere near. However, this is not a problem to 600yds, and the 6.5x47L can push ~130gr bullets to as much in accuracy potential as the bigger cartridges -more consistently, and with many other advantages over the bigger cartridges.
The 260AI and ~140gr bullets for 1kyd shooting extends similar advantage over the larger 6.5x284, AND the smaller 6.5x47L (overall).

That makes sense, at least the parts I understand, esp. the later part.
To put it simply, with both loaded in the optimum fashion, what is the estimated diff in barrel life & velocity with 140 grain bullets and let's say 26" tube each?

 

[Mikecr]

26" is a bit short for the 6.5x284. It has to burn more slower powder than the 260AI.
Barrel life is another thread. But accurate barrel life of a 6.5x284 is well established at ~1200rnds.
A 260AI loaded to ~3025fps/140gr bullets can better this by 500rnds.
The difference is 8gr excess in powder with the 6.5x284, to get that same MV.