260 Remington AI vs 6.5 x 47 Lapua

[thomasholbrook43]

I agree with shootsdots. I just built a 6.5x284 and i have a 260AI hunting rig. My 260 AI will shoot circles around the 6.5x284. An with the right powder you can run the same speeds with no problem. The 260AI is very close to dasher accuracy.

 

[savagedasher]

I agree with shootsdots. I just built a 6.5x284 and i have a 260AI hunting rig. My 260 AI will shoot circles around the 6.5x284. An with the right powder you can run the same speeds with no problem. The 260AI is very close to dasher accuracy.

Plus 1 on that. Its the best 6.5MM you can shoot. Larry

 

[280nosler]

Anything comes with a trade off.
The 6.5x47 has great brass life, but maxes out 200 Fps shy of the 260 AI.

The 260 AI has terrible brass life (4-6) loadings depending on the speed of the 140 bullet, and you will have a higher likelihood of a pierced primer or the brass not holding a primer.

Again, everything is a trade off.

If you want extra velocity, consider the 6.5x47 with a 29" barrel, or reform 308 palma brass down to 260, then fire form up to 260AI. Only way to get the best of both worlds.

 

[flatlander]

I shot a couple of 6.5x47s in XC & 1000yd LR any/any prone matches for several years, and never felt under-gunned, even though I ran mostly 130VLDs at just over 2900fps instead of 140s.

Built myself a 260 Imp 30* a couple of years ago for use in practical/tactical steel matches, and have been very pleased with its accuracy. Have never come close to the velocities some here are claiming for their 260AIs, settling instead for 2840fps with various 140s out of my rifle's 26" bbl.

Now I've got a 26" 6.5x47 bbl on one of my comp rifles, and have found it possible to get just a hair over 2800fps with 140s using IMR 4451. This rifle weighs within an ounce or two of the 260 Imp, so recoil is very similar. Point I'm trying to make is that either cartridge can be excellent for MR & LR use. When it comes to the velocities some of the guys here are running, all I can say is that brass is still too scarce & expensive for me to feel 'right' about pushing the 260 Imp that hard. To each his own...

 

[alphapygmy]

I run a 260AI in my local club 600 league and have had excellent brass life. I'm currently on 9 firings and the pockets are still good running 140's at 2900-2925. Not tight like new but I still expect to get a several more firings out of them. I think if you're having poor brass life with an AI you're probably running them too hot and not seeing pressure signs. They seem to hide pressure signs better than non improved cases so you can over pressure them and you don't see it until your pockets get loose. Having said that I alternate between large primed brass and Palma small primer brass just for an experiment. The Palma brass stays tighter longer but I see a little more vertical, I'm guessing the case capacity is right on the border of what a small primer can consistently ignite.

 

[M14AMU]

Here's the 'mall ninja' at work from 1000 yds.

6.5x47Lapua 15 rounds

6.51000 by Rick Mulhern, on Flickr

 

[mikecr]

It all begins with a bullet. You build capacity around that.
The 260AI is perfect capacity for 140gr bullets, and it's a well improved design. Far better for 140gr bullets than either a 260 or 6.5x284. Eventually it'll catch fire in 1kyd.
The 6.5x47L is a great capacity for 130gr bullets, which in my view, makes it a perfect mid-range cartridge. If it hasn't already proven that, it will.

 

[Changeling]

For those running the 308 AI Palma brass and getting high 2900's to 3100 fps out of your rifles (30" barrels ?), do you actually know what pressures you are running at or, are you just estimating that it is OK because you are not seeing pressure signs (Custom actions ?) ?

 

[M14AMU]

For those running the 308 AI Palma brass and getting high 2900's to 3100 fps out of your rifles (30" barrels ?), do you actually know what pressures you are running at or, are you just estimating that it is OK because you are not seeing pressure signs (Custom actions ?) ?

We were pushing to that velocity a long time ago.....and several individuals that worked with the US Palma Team found no pressure signs!

 

[dennisinaz]

I have both and a 260AI run to the same velocity as the 6.5-284 is at least 10KSI higher in pressure. Custom actions, tight chambers etc will hide that pressure pretty good- doesn't mean is OK.

I started out with a 260 rem. By the third barrel I decided it was just never going to shoot like I wanted. I bought a 260AI reamer and opened it up. I cut group sizes in half and gained 150 fps. The 260AI is an awesome round. It was noticeably more accurate than the parent chambering.

I am running shorter barrels- 22-25" so my velocities are not anywhere near the F-class 30" length velocities but with the right loads I can safely push 140s to 3080 in the 6.5-284 and about 2900 in the 260AI.

I am going to put together a new rifle in 6x47L to take advantage of the small primer pocket whereas I could have opted for the 6mm Super LR and been stuck with large.

 

[alphapygmy]

I'm running a 260AI right now in my club level 600 yard league. I'm ready to order a barrel for next year's rifle and I can't decide if I want to stay with 260AI or try the 6.5x47. It will only be used out to 600 so I'm leaning towards the 6.5x47 but I've been real happy with how the 260AI has done for me. I've been watching this thread to help make up my mind and I still can't decide. Guess I need one of each!

 

[Fireformed]

I shoot 3 different boring ole 260s. 2 custom built and one savage out of the box. 2 are on their second barrel and the savage I'm cutting and crowning this week.

I'd go with a 260AI next for sure. I've not necked down brass for my 260s I've neck up 243 when I needed. Greatest success and smallest groups have come with lapua but the primer pockets have not held up passed 5 loads.
With the Palma 308 lapua brass necked down what velocity increase would I get? I'm accurately at around 2880+ with 140 smk. Would I get a few more loading out of the brass?

Interesting topic for sure.

 

[P72]

Cost aspects for converting a small rifle rim diameter, .378 inch bolt face/bolt to standard large rifle diameter .473 inch? Also consider feed aspects such as magazines.

Is there some magic about Ackley improved cartridges that would enable the smaller .260 AI to get higher velocities than the larger 6.5-.284, assuming same other stuff?

Now would be the time to present factual data to address that not just anecdotal impressions.

Load some cartridge to close to 65 thousand psi and naturally primer pockets will expand. Anybody out there actually performed pressure measurements on their .260 AI ?

 

[mikecr]

Cost aspects for converting a small rifle rim diameter, .378 inch bolt face/bolt to standard large rifle diameter .473 inch?

What cartridge are you referring to with a 378 case head? Unless I missed a detour subject cartridges are all 473.

Is there some magic about Ackley improved cartridges that would enable the smaller .260 AI to get higher velocities than the larger 6.5-.284, assuming same other stuff?

No magic. Cartridges have been improved over many years, which is why we have so many choices today..
Velocity/pressure-wise the 260AI more viably provides 140gr bullets at 3000+fps than a 6.5x284, because it has the correct capacity to do so in a smaller/better chamber area.
Where you can get it done like this, brass and barrel life improve(at given pressure). Longer stretches with same components, means consistent system performance over longer periods.

Now step back to 123-130gr bullets, and the 260AI is no longer best capacity, (forget a 6.5x284). Best here could be a slightly improved 6.5x47L. Here, there is 1gr capacity gain with a 40deg shoulder, slightly less body taper. The brass wouldn't have to be pushed so hard with this, but it could better handle it if chosen.

A person can also use improvements to run at decided velocities -with a bit lower pressures.

 

[P72]

I am lead to believe that the rifle to be converted is a Rem 700 .204 Ruger (re-barreling M700 .204 Ruger) and that has a .378 inch diameter rim size and all the rest of the cartridges to be considered have .473 rim diameters. This difference will require a new bolt or extensive machining to open up the bolt face. In addition the ejector location in the much smaller .204 Ruger with its much smaller rim size of .378 will be located closer to the center of the bolt face than a Remington 700 rifle intended for a .473 rimmed cartridge. More work will be needed, like installing a new magazine. Not being a Remington fan, because of my dislike for Remington 700 extractors, there also may be issues in the size of the opening cut in the bottom of the tubular receiver to accept a magazine box for a small rifle cartridge like a Ruger .204 with its .378 rim diameter.

The benefits of the 40 degree shoulder Ackley cartridges are marginal to moderate. The moderate ones being the .22-.250 and 6mm or .244 Remington both of which have pronounced body tapers allowing some 10 percent volume increase upon being subjected to the Ackley improvement.

As far as the size vs. shape business Rifle and Handloader magazines ran tests on the old .300 H&H Magnum and the vastly improved, modern, short powder column beltless .300 WSM (Winchester Short Magnum) the findings were that volume or case capacity was almost equal (variations expected due to brass manufacture and lots), velocities and variations of which were essentially equal.

Cartridges have been improved over the years but some have been abject failures such as the .225 Winchester and .300 RSAUM and I would expect the Ruger short magnums will follow - no brass, no reform, no shoot. Apparently there is some motivation to make new stuff for some perceived need only to have it fail because shooter rejection. A 1 grain powder increase realized by improving the already "improved" 6.5X47 Lapua (probably designed for 300 M with long barrel life and also competitive to 1000 yards) might increase the velocity by 15 fps, possibly Lapua engineers/designers should be advised and be encouraged to start working on this improvement.

I take it that, "more viably provides 140 gr bullets at 3000+fps than a 6.5X.284" means the much smaller .260 AI with a capacity of 56.96 can produce more advantageous velocities than the larger 06 sized 6.5-.284 under some "viability" constraint. To support a claim like this data must be presented showing velocities and velocity variations for both cartridges and pressure measurements.

As present, you have failed to present such data but have only made claims such as "smaller/better chamber area" which I suspect is largely subjective.

As expected and logically the smaller 6.5X47 Lapua will not shoot a 140 as fast as the .260 AI but a .260 AI will shoot a 123 faster than a 6.5X47 Lapua with slightly less wind drift at ranges like 600 and 1000 yards. This would, to me make the term, "viable", non-operable (forget it).

 

[mikecr]

You're over focusing on velocity.
Take velocity off the table for moment and consider other advantages to improved cartridges, and then add these up.
Consider bullets first, then capacity for them given available powders, then component stability over a long run.

The 6.5x47L is a great example of improvement over the old 260.
It doesn't provide higher MV than a 260, but it's a better cartridge in every respect otherwise.
My contention with improving a 6.5x47L slightly was not for velocity at all. It was for sparing expensive brass life.
Now you can argue that improving cases is insignificant.
You can also review the last years worth of IBS equipment lists and you'll see 6.5x47Ls doing well here & there.
Then consider the 260s showing..

Shooting 123gr bullets faster, is not going to make them more accurate. I'll predict right up front that a 123gr bullet will never be more accurate in the long run(what matters) from a wrong capacity cartridge(6.5CM,260,260AI,6.5x284) -vs- the right capacity(6.5x47L).
And it's my contention that the 260AI represents the perfect capacity for 140gr bullets. That nothing existing will shoot 140gr bullets better(which is more than MV) in the long run, than 260AI capacity.

In summary, in 26cal, I think the 6.5x47L will be king at mid ranges, and same for the 260AI at 1kyd. They'll do it with the same barrels, same MVs(different bullets), both in Lapua brass, and leaving every other 26cal cartridge in fading history.
I can't prove it, it's just my opinion.

 

[jpretle]

And it's my contention that the 260AI represents the perfect capacity for 140gr bullets. That nothing existing will shoot 140gr bullets better(which is more than MV) in the long run, than 260AI capacity.

mikecr, have you considered the 6X55AI in the above context???

 

[Changeling]

HUH : > ???, OH well whatever! 8)

 

[mikecr]

mikecr, have you considered the 6X55AI in the above context???

Yes, and I realize the standard 6.5x55 swede is very popular.
It's capacity(~57gr) exactly matches the 260AI, so this doesn't surprise me a bit.
But it's not improved.

The 6.5x55AI holds 5gr more H20 capacity than the 260AI, and it's improved.
But it won't viably reach and shoot well at the next nodes above the ~2950-3050fps nodes.
That makes the extra 5gr capacity, 5gr in excess(potentially).

It's close, but the 260AI has minimum capacity to reach what I call the mid-nodes with 140gr bullets with excellent load density in 4350 powders. And being improved we can run competitive pressures in doing so(good for accuracy). I believe accurate barrel life would be a little higher(not much) than with the 6.5x55AI at good load densities.
There may be issues with some over the case head and length differences. I don't get it there.
It's close.

 

[Changeling]

This thread might be of interest to 260 users:

http://www.6mmar.com/260_Imp_30_.php