Range Report Is the 260 AI a logical choice over the 6.5x47 L?

[Alan Griffith]

I'm looking for some intelligent, no BS, answers.

Some of you may already know I run a 6.5x47 in a 26" Broughton 1:8 barrel and a Pierce action. With every ounce of my 37+ years of reloading experience I've found I can run Berger 140 VLD's to almost 3000 fps with zero pressure signs, only getting a hint of bolt lift just over 3000 fps.

My best friend has taken his 6.5x47 in a 25" Krieger 1:8 with 130 Berger VLD's to 3150 fps, again with zero pressures signs. We both used Rel 17 and CCI 450 primers.

When we talk about pressure signs, we're talking about chrono readings, primer condition, primer pocket condition/tightness, case head expansion, bolt lift, ejector marks, etc.

He is getting ready to have a lighter hunting rifle built on the same, Pierce, action I built my light weight rifle on.

Can anyone give some sane reasons he should go with a 260 Ackley Improved instead of staying with the 6.5x47?

Thanks for thoughtful replies!

Alan

 

[RobertB]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Thats impressive speeds for that bullet weight I would think. I would have also believe that the .260 should deff give more speed than the x47. I have a 6.5 Lapua and a 260 (non AI) and while I don't have a crony I don't believe I'm getting those speeds.

 

[BOLTRIPPER]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

a ackley improved will blowtorch them little boolits at very brisk speeds as it also blow-torches the barrel....read short barrel life.......bullets will pattern up close but come into there own out long.....

there are a lot of summer time tomato gardens that grow somewhat tall due to all the burnt up ackley improved barrels straightening them out

 

[Rich Emmons]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

buy another chronograph
edit to add; can't help you with intelligent answers but i am staying at a holiday inn, right now.

 

[FCS]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

No logical reason to go to a 260 AI over 6.5X47 for your friend.

I've got a long neck, 260 improved and you are getting pretty much same performance with the X47. However, you have to run a double base powder to do so and I'm running a single base powder. Double base is going to be more temp sensitive

 

[ChadTRG42]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<span style="font-style: italic">IF</span> you are getting these speeds, then stick with it. But, if those speeds are correct, you are running hot loads, no doubt. Those speeds are faster than a standard 260 by alomost 200 fps, and the x47L is a smaller case by about 4 grains of powder. The only way to get those speeds is with more pressure. Are these velocities confirmed with your drop at distance?

 

[Jedi]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

2950-3000fps very doable with longer barrel ie 30"
alot of guys on 6br run this combo myself included.
6.5x47 brass is super tuff n running RE17 you can get 6.5-284 match fps 2950 or so pert easy n match accuracy.
If ya must change go with 6.5GAP basically ack 6rem necked up, very nice concept.Or stay with the 6gap but 260/243/308 suffer from bad case design unless you change it via 6SLR or 6BRK n push shoulder back ... stick with what you have

 

[260shtr]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Lapua 260 brass coming out. It will no doubt hold more pressure.In a AI case you could get the same velocity with less pressure with a powder like H4350 or run blistering speeds with Re 17.

 

[psinclair]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Pretty good advice above from a few guys in "the know".

 

[FCS]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 260 shooter</div><div class="ubbcode-body">Lapua 260 brass coming out. It will no doubt hold more pressure.In a AI case you could get the same velocity with less pressure with a powder like H4350 or run blistering speeds with Re 17. </div></div>

I am running Lapua brass, 243 Win necked up and neck turned using fluted mandrel to cut out donut. I get ejector swipe about 2950 fps w/140 JLK. I might not have had quite enough clearance on necks, might have been getting high pressure signs due to that. Working on turning those necks for touch more clearance, will see how much difference it makes.

Downside of Re 17 is it being a double base and more temp sensitive. Know of a top F-open shooter who went back to H4350 for that reason.

 

[Rootshot]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

No! I can't get those velocities out of my 6.5-08AI(260AI) with bullets in the 140gr range with a 26" barrel. Stick with the 6.5x47.

--Rootshot

 

[psinclair]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FCS</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 260 shooter</div><div class="ubbcode-body">Lapua 260 brass coming out. It will no doubt hold more pressure.In a AI case you could get the same velocity with less pressure with a powder like H4350 or run blistering speeds with Re 17. </div></div>

I am running Lapua brass, 243 Win necked up and neck turned using fluted mandrel to cut out donut. I get ejector swipe about 2950 fps w/140 JLK. I might not have had quite enough clearance on necks, might have been getting high pressure signs due to that. Working on turning those necks for touch more clearance, will see how much difference it makes.

Downside of Re 17 is it being a double base and more temp sensitive. Know of a top F-open shooter who went back to H4350 for that reason.

</div></div>

.243 Lapua necked up....agreed. Remove the donut and GTG.

Totally +1 on Re17. I found that out the hard way hunting in sub zero temps a few years ago. H4350 occupies my shelf space now.

 

[Alan Griffith]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 260 shooter</div><div class="ubbcode-body">Lapua 260 brass coming out. It will no doubt hold more pressure.In a AI case you could get the same velocity with less pressure with a powder like H4350 or run blistering speeds with Re 17. </div></div>

Why would you say the Lapua 260 brass will hold more pressure? I'm sure it will be of best quality but it will be spec'd just about like any other 260 brass.

Alan

 

[FCS]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

260 has been hamstrung by lack of brass that will take higher pressure loads. RP has a long and well documented history of losing pockets if running warm to hot loads in their 260 brass.

I've run same load in RP brass and Lapua brass in my 6.5 MIC (long neck 260, 40 degree shoulder) and have yet to lose a Lapua primer pocket. RP is maybe 2 loadings before pocket is really loose.
Winchester is a little better but not enough better for me to form up 6.5 MIC.
Lapua 243 necked up, turned to remove donut was hands down best brass available for 260 prior to Lapua coming out with factory 260 brass.

260shooter is stating the obvious, Lapua handles pressure better than pretty much any other brass available.

Why do you think you are able to get the velocities you are with the 6.5X47? Because Lapua brass takes the pressure. Form up some Win brass into 6.5X47 and see what you can get before you have pressure signs/loose pockets on second firing.

 

[ranger1183]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GSSP</div><div class="ubbcode-body">Can anyone give some sane reasons he should go with a 260 Ackley Improved instead of staying with the 6.5x47?</div></div>
I have owned two different 260 Remingtons and now own a 260AI and I run it pretty hot. I use a variety of brass, mostly Nosler 260, Winchester 7mm-08 and some Remington brand 260 brass. Here's my take. If you can get near 3000 fps with a 6.5x47 Lapua firing a 140 grain projectile, you are getting just as much as you can reasonablely get by blowing the shoulder forward on 260 brass to make it 260AI. Can you pack more powder into the 260AI case and make it go faster? Sure. But it's a waste of serious money. You have to buy the brass, the reloading dies and then LOTS MORE brass as you will be blowing primers after a very few reloads. That money could be much better spent on new barrels, new optics or a better hunting rifle. Just my experience with the 260 and the 260AI.

 

[Casey Simpson]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Is the 260 AI a logical choice over the 6.5x47 L?

No. In other words, what do you mean? A 7 STW is a logical choice over a 6.5x47L, so is a 7RSAUM, 6.5x284win, 6XC, even 243Win. But x47 does what it does well. I shot one about 2000 times.

At the point where ballistics are as close as 260, 65cr, x47, xc, 243, 6mmRem,, the ballistics do not separate the performance / outcome at the match. Settle for the round your instincts tell you to.

As for 260ai, seemingly short, fatter cases are more efficient, i.e.; br, ppc, wsm.
260ai versus 47? Which one is more interesting to you, or gives you a better feeling even ever so slightly? Choose that one.
Hope this helps. This is what I know I should do when debating a selection.

 

[Alan Griffith]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FCS</div><div class="ubbcode-body">
260shooter is stating the obvious, Lapua handles pressure better than pretty much any other brass available.

Why do you think you are able to get the velocities you are with the 6.5X47? Because Lapua brass takes the pressure. Form up some Win brass into 6.5X47 and see what you can get before you have pressure signs/loose pockets on second firing. </div></div>

FCS,

My train of thinking may be all wrong and if so, then so be it as I have zero experience with converting any brass to 260 Rem. I used Rem and Nosler in my 260's. So, if Lapua 243 brass converted to 260 Rem is stronger than others then my thinking is to "handle pressure better" it must be thicker in the web area than other 260 brass. If it's thicker, then it's heavier, both of which contribute to less volume and I'm pretty sure leads to less velocity. Unless Lapua uses some proprietary formula for their brass which is stronger than other brands.

Now, if someone has compared water volume of converted 243 Lapua cases to Win/Rem/Nosler cases and is basically equivalent then I'll concede and go right along accept that Lapua is inherently stronger.

As for the 6.5x47 handling higher pressures, IMHO, it is, in deed, due to the stronger/thicker web areas since it uses a small rifle primer. I've actually run into "knowledgable" shooters/reloader's who did not realize the 6.5x47 uses a small rifle primer and were convinced I was destroying my brass with my loads. I still run my original 6.5x47 brass that I did load workup with that have numerous ejector marks and bolt face smears that still have tight primer pockets after 7+ firings.

Alan

 

[260shtr]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

My experience is with necked up 243 Lapua brass in a 260. I used Win 7-08 brass(good brass but 4 Loads and loose pockets). When I switched to Lapua and changed nothing else, I gained 50 fps with no pressure signs. I believe I could run it a LOT hotter than the 2940 fps W/123 Lapua but the accuracy is quite good so I don't fell the need to go faster.

My Dad has a 260AI and is getting 2940 fps with a 139 Lapua and Rem brass with a mild load of H-4350. My theory is if he could gain 50 fps by switching to Lapua brass and put another 1-1.5 gr of powder it would exceed the 3000 fps. But this is just a theory for now. Is it worth it to change everything up and fireform brass to maybe gain 50-100 fps is the question.

Give me some time for the weather to get better and I will run the test with 5 Lapua cases out of the 260AI and I will report back.

 

[raptor99]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Not being a wise ass or anything but I think you need to check your cronograph. I was getting some pretty good numbers on my 260 until I shot it across two new cronographs and lost about 100fps. over my readings.

I also would like to know how your figures compute to real world ballistics. I have a good friend who shoots with me and has a 6.5x47 and he can not shoot as flat as my 260 does using the same bullets. He is at the point of flattening primers and getting loose primer pockets with his if he goes any hotter. I am around a MOA flatter shooting than his and I have an inch shorter barrel.

I am not into the one is better than the other because as stated above all three of the 6.5s are really nice rounds and all will shoot great. I just think that a lot of the guys touting the 6.5x47 velocities need to get some different cronographs.

Out of all three of the 6.5s the 6.5x47s is the smallest case and the 260 is the largest.

 

[Adam B]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

from me experience the minimal gain you get from the 260AI vs the 260 isnt worth the work it takes to prep the brass. Now that Lapua is bringing out 260 brass I would stick with a standard 260 and never look back

 

[FCS]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Alan,

I'm not case capacity limited with the Lapua 243 necked up to 260. I am getting pressure signs.

I have not done water capacity between RP 260 formed into 6.5 MIC and Lapua 243 formed into 6.5 MIC, I do know there is about a 0.5 gr difference in powder charge to get same velocity. RP needs more powder to get same velocity as it has slightly more case capacity than Lapua. Only if you are capacity limited does your argument of less capacity come into play. If you have a case with "excessive" case capacity it works against you as you'll need more powder to get same velocity

Every brass mfg'er has their own alloy, heat treat process, etc. I fully admit I've not hardness tested every brand of brass, I have ran pretty much every brand of brass in my 6.5 MIC and clearly the Lapua holds up better. I've yet to lose a primer pocket w/Lapua brass. RP loses pocket on second firing, maybe 3rd on some pieces of brass. Win is maybe 3rd to 4th firing. I've got Lapua brass with 10+ firings that is used in my F-open rifle.

If we go back to the original question, is 260AI a logical choice over 6.5X47 I still say it is not a logical choice even with factory Lapua 260 brass. 260AI requires fire forming, more expensive die set, notching of feed ramp on R700, different mag box, etc so you can get out to 2.950" or so OAL to really take advantage of the extra case capacity. When all said n done, the 260AI is going to gain you a larger powder charge w/negligable gain in velocity or worse yet the same velocity you can get with X47.

If you friend wants a 260AI to satisfy an itch, well that is a different story. Running a Rem 700 SA footprint, the 6.5X47 is dang hard to beat. If I had not made up the 6.5MIC prior to Lapua coming out with the 6.5X47, I'd be running the X47. Custom die set from WTC, formed up nearly 2K pieces of 6.5 MIC brass, etc I'm just a bit too invested in the 6.5 MIC to justify moving over to the 6.5X47. Once I've wore out all the MIC brass, might just move over to the X47 for ease of getting new brass, small primer pockets, and increase in barrel life.

 

[mtn grizzly]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Some great responses - but many are still questioning the velocity numbers on the little 6.5 X 47L. I am running a CED M2 Chronograph and here are the actual numbers that I got just last week out of a 25" Kreiger with an 8.5 twist

130 Berger VLD over 44 Grains of R17 / CCI 450 Velocity 3148 FPS

My Lapua cases had 7 firings on them and I noted (0) increased bolt lift. I measured case head expansion @ .0003. I immediately went home and sized and primed the cases that I thought that I had abused and the primers seated like they were new cases!

I am beginning to think that we are all looking at the size and volume of this little case and missing something very important! My 30 years of reloading experience tell me that I pushed the pressures too high during my test BUT the 47L case is not validating my concerns.
I dont see anybody claiming higher performance out of their 260 or 260 AI.

Whats going on here? Did Lapua do something magical with the 47L?

 

[notquiteright]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Grizzly-
When the 6.5x47 first started making an appearance in F-Class a handful of years ago many questioned its capablities vs the 260.

I was one of them.

In the years since I have to say there must be something magical in them!

I dont own one, may never own one, but sure admire them!

If I was to abandon the 308, I believe the 6.5x47 would be sweet, lack of recoil even compared to the mild 260, coupled with excellent ballistics works for me.

 

[Alan Griffith]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Mtn Grizzly and I appreciate the "well thought out" answers provided by the members here. Ultimately it's his decision. I think he's still sittin on the fence. My issue with the 260 is the short mag length, OAL of seated 140 gr VLD type bullets and chasing the lands. Thus far my 6.5x47 has grown about 80 thou on the throat bringing my OAL to 2.788 after about 700+ rounds. It's got 900+ now and it's due for a re-measure. Maybe not; I shot a .49" 10-shot group last week with it. When I run out of mag room I'll just have the barrel set back a bit.

As far as chronograph issues, I did compare velocities between my everyday 130 Berger VLD/H4350 load that is shot in my Surgeon on both my CED M2 and new Oeher 35P; within 1 fps for a 10-shot string. With that said, I trust my 35P to tell me the true velocities of the 140 gr/Rel 17 speeds.

I also realize I'm shooting in safe territory because Erik Cortina of Houston, TX, a world class F-class shooter is doing the same thing with 139 Scenars which are known for being about .0005 fattter in diameter and sometimes lead to higher pressures. He, too, topped 3000+ fps before seeing the slightest pressure issues.

Alan

 

[mtn grizzly]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Just took a water capacity measurement

6.5 X 47L 47.39 Grains of Water

260 AI 57.43 Grains of Water

A difference of 21%

 

[Hondo64d]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body"><span style="font-style: italic">IF</span> you are getting these speeds, then stick with it. But, if those speeds are correct, you are running hot loads, no doubt. Those speeds are faster than a standard 260 by alomost 200 fps, and the x47L is a smaller case by about 4 grains of powder. The only way to get those speeds is with more pressure. Are these velocities confirmed with your drop at distance? </div></div>

No doubt higher pressures in the 6.5x47, but don't you think the small primer pocket allows the case to handle the higher pressure better?

John

 

[Alan Griffith]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hondo64d</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body"><span style="font-style: italic">IF</span> you are getting these speeds, then stick with it. But, if those speeds are correct, you are running hot loads, no doubt. Those speeds are faster than a standard 260 by alomost 200 fps, and the x47L is a smaller case by about 4 grains of powder. The only way to get those speeds is with more pressure. Are these velocities confirmed with your drop at distance? </div></div>

No doubt higher pressures in the 6.5x47, but don't you think the small primer pocket allows the case to handle the higher pressure better?

John </div></div>

John,

Absolutely, frickin, on the nose! And, a few are running with the idea that Lapua brass has a higher tolerance for higher pressures. I'm warming up to that theory.

Alan

 

[ChadTRG42]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hondo64d</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body"><span style="font-style: italic">IF</span> you are getting these speeds, then stick with it. But, if those speeds are correct, you are running hot loads, no doubt. Those speeds are faster than a standard 260 by alomost 200 fps, and the x47L is a smaller case by about 4 grains of powder. The only way to get those speeds is with more pressure. Are these velocities confirmed with your drop at distance? </div></div>

No doubt higher pressures in the 6.5x47, but don't you think the small primer pocket allows the case to handle the higher pressure better?

John </div></div>
Yes. It has been engineered to handle higher pressures. From a design stand point, the 6.5x47L is about as perfect of a case as you can get. The shoulder angle, the small primer pocket, the good brass. It has me baffled at the overall performance I've seen with it. I had a 2 fps extreme spread shooting the 140 VLD's well under 1/4 moa accuracy at 300 yards. The accuracy and consistancy of the caliber is awesome. I wouldn't hesitate to run this caliber, but I loose too much brass, and the x47L brass is much more expensive than Rem 260 brass is.

But, I still don't see how you can get the 200+ fps increase over a 260 Rem with a smaller case, and not have an overly high pressure load. If guys are getting these speeds with no "pressure signs", then that's impressive. But the only way to get these speeds is with more pressure. I wouldn't risk running these speeds for my everyday tactical/match round. I've seen many times guys run hot loads, and during a match they have to stop shooting because of blown primers, and other hot ammo problems. Just give me a good, accurate round pushed at decent speeds, and let me go shoot it. I'm not trying to break any speed records with a caliber.

 

[BobinNC]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

I don't have a dog in this fight, preferring 7mm sized bullets to 6.5mm sized one's.

Before everyone gets all giddy over the relative strength of 6.5x47 and it's higher tolerance for higher pressures should consider the following:

MAX SAMMI Pressure 260 Remington 60,000 PSI

As comparison the MAX SAMMI/CIP pressure for the 308 Winchester is 62,000 PSI. Since the 308 is the parent case of the 260 Rem, for all intents and purposes a reloader could feel free to run the 260 Rem up to 62K PSI or so.

Hodgdon Lists MAX velocities for the 260 REM in the 2750 FPS range @ 58,000 PSI for 139-142 grain bullets.

If you run the 260 up to 62-63K PSI, your realizing velocities in the 2825-2850 FPS range, which is plenty of velocity for most tactical shooting, and still have reasonable brass life.

Now looking at the 6.5x47

MAX CIP Pressure for the 6.5x47MM as set by Lapua 63,090 PSI

Factory 6.5x47 Lapua ammo is rated as:

108-grain Scenar at 2950 fps
123-grain Scenar at 2790 fps
139-grain Scenar at 2690 fps

Now I'm pretty sure that Lapua factory ammo is not running anywhere near 63K PSI with those loads. Just guessing I would venture to say the average pressure of those loads is in the 58-60K PSI range. Or about the same as Hodgdon lists as MAX average pressure loads for the 260 REM.

In other words the difference in velocity 2690 vs 2750 FPS with a 139-142 grain bullet is about what one would expect from the 4 grains difference in case capacity, and not brass strength.

So now the question becomes, can a reloader juice a 6.5x47mm to produce nearly 3000 FPS with a 139 gr Bullet and 3150 FPS with a 130 grain and no apparent pressure signs?

The original OP, GSSP can and does achieve those velocities, apparently without pressure signs. But what pressure is he really running? 70k PSI or more?

Keep in mind that CIP proof loads are rated as 25% over nominal rating, so that 6.5x47mm Proof loads run about 79 K PSI.

The good news is the 6.5x47mm case can take those kind of pressures without complaint. The bad news is: why would you want to run 70 K PSI+ loads in the first place?

What can you do with a 139 gr bullet @ 2950 FPS + running 70 K PSI or better, that you cannot do with the same bullet @ 2850 FPS and 5K PSI or more less pressure?

If the answer is "because you can", is insufficient to be running near proof loads every time one pulls the trigger on a 6.5x47mm round, just to realize an extra 200-300 FPS.

Think about it a bit,

Bob

 

[Jayman_10X]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Given the recent development of Lapua introducing the 260 Rem brass this spring, I don't see the need for using a 260 AI when you already have a 6.5x47L. What are you really going to gain? It generally established that the ratio for increased grain capacity to velocity gain is only 1:0.25. John Barsness reported this phenomena whilst comparing the case capacity difference between the 300 H&H and 300 Weatherby. For my money I'm going to use a 260 Rem stoked with Lapua brass and be thankful.

I don't know about you guys but I'd rather purchase that good Lapua brass and concentrate my time shooting than waste time and money performing the menial and redundant tasks of brass prep for a 260 AI only to achieve practically nothing.

 

[Alan Griffith]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">I don't have a dog in this fight, preferring 7mm sized bullets to 6.5mm sized one's.

Before everyone gets all giddy over the relative strength of 6.5x47 and it's higher tolerance for higher pressures should consider the following:

MAX SAMMI Pressure 260 Remington 60,000 PSI

As comparison the MAX SAMMI/CIP pressure for the 308 Winchester is 62,000 PSI. Since the 308 is the parent case of the 260 Rem, for all intents and purposes a reloader could feel free to run the 260 Rem up to 62K PSI or so.

Hodgdon Lists MAX velocities for the 260 REM in the 2750 FPS range @ 58,000 PSI for 139-142 grain bullets.

If you run the 260 up to 62-63K PSI, your realizing velocities in the 2825-2850 FPS range, which is plenty of velocity for most tactical shooting, and still have reasonable brass life.

Now looking at the 6.5x47

MAX CIP Pressure for the 6.5x47MM as set by Lapua 63,090 PSI

Factory 6.5x47 Lapua ammo is rated as:

108-grain Scenar at 2950 fps
123-grain Scenar at 2790 fps
139-grain Scenar at 2690 fps

Now I'm pretty sure that Lapua factory ammo is not running anywhere near 63K PSI with those loads. Just guessing I would venture to say the average pressure of those loads is in the 58-60K PSI range. Or about the same as Hodgdon lists as MAX average pressure loads for the 260 REM.

In other words the difference in velocity 2690 vs 2750 FPS with a 139-142 grain bullet is about what one would expect from the 4 grains difference in case capacity, and not brass strength.

So now the question becomes, can a reloader juice a 6.5x47mm to produce nearly 3000 FPS with a 139 gr Bullet and 3150 FPS with a 130 grain and no apparent pressure signs?

The original OP, GSSP can and does achieve those velocities, apparently without pressure signs. But what pressure is he really running? 70k PSI or more?

Keep in mind that CIP proof loads are rated as 25% over nominal rating, so that 6.5x47mm Proof loads run about 79 K PSI.

The good news is the 6.5x47mm case can take those kind of pressures without complaint. The bad news is: why would you want to run 70 K PSI+ loads in the first place?

What can you do with a 139 gr bullet @ 2950 FPS + running 70 K PSI or better, that you cannot do with the same bullet @ 2850 FPS and 5K PSI or more less pressure?

If the answer is "because you can", is insufficient to be running near proof loads every time one pulls the trigger on a 6.5x47mm round, just to realize an extra 200-300 FPS.

Think about it a bit,

Bob
</div></div>

+1 for Bob's post.

And the hunting load I settled on in my little Pierce runs the 140 Partitions @ 2850 fps but it sure was nice to be able to run it faster if I needed to. That's just where my accuracy node happen to be. Many times we find the accuracy node somewhere around the pressure ceiling of our individual rifles.

Oh, and Bob. We won't hold it against you that you're dog is a 7mm

At least it's a metric

Alan

 

[BobinNC]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Alan,

My 7mm-08 says Woof Woof.....

Bob

 

[Casey Simpson]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

This thread reminds me that when a guy asks what you think it really means he's already made up his mind but he want to see if someone else will sign off on what he wants to do.

Rats! He trolled and I took the bait.

 

[sandwarrior]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Jeez,

I don't know why we argue this and argue this. Get a 6.5 barrel, cut a 6.5x55 AI chamber, run LOW pressures (saves barrel) and gets better velocity than 6.5x47.

Oh yeah, the kicker here is use <span style="text-decoration: underline">Lapua 6.5x55 Swede</span> brass. It's durable like no other.

And the main point of using an Ackley case is to lengthen case life. Not, as Ackley himself mentioned, to take the bullet to the extreme of velocity.

FIND THE EXTREME OF ACCURACY AND STICK WITH IT~!

 

[Alan Griffith]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sandwarrior</div><div class="ubbcode-body">Jeez,

I don't know why we argue this and argue this. Get a 6.5 barrel, cut a 6.5x55 AI chamber, run LOW pressures (saves barrel) and gets better velocity than 6.5x47.

Oh yeah, the kicker here is use <span style="text-decoration: underline">Lapua 6.5x55 Swede</span> brass. It's durable like no other.

And the main point of using an Ackley case is to lengthen case life. Not, as Ackley himself mentioned, to take the bullet to the extreme of velocity.

FIND THE EXTREME OF ACCURACY AND STICK WITH IT~! </div></div>

Well, hell Sandwarrior, with that attitude, we should all shoot the 338 Lapua ooorrrrr maybe we should get Lapua to start making 50 BMG or 20 Mic Mic. Jeez!

Alan

 

[sandwarrior]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GSSP</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sandwarrior</div><div class="ubbcode-body">Jeez,

I don't know why we argue this and argue this. Get a 6.5 barrel, cut a 6.5x55 AI chamber, run LOW pressures (saves barrel) and gets better velocity than 6.5x47.

Oh yeah, the kicker here is use <span style="text-decoration: underline">Lapua 6.5x55 Swede</span> brass. It's durable like no other.

And the main point of using an Ackley case is to lengthen case life. Not, as Ackley himself mentioned, to take the bullet to the extreme of velocity.

FIND THE EXTREME OF ACCURACY AND STICK WITH IT~! </div></div>

Well, hell Sandwarrior, with that attitude, we should all shoot the 338 Lapua ooorrrrr maybe we should get Lapua to start making 50 BMG or 20 Mic Mic. Jeez!

Alan</div></div>

Let me get my padding strapped on and we'll go do it eh?

I know what you're saying. To each their own. But, I do get to the point where I've just showed someone seven times what a 7mm-08 will do over a .260. But, the .264/6.5mm shooters do have a good point. They get more velocity than the 7mm's out to 1k so it makes sense. When you go beyond that is where the 7mm's take over. But, the 6.5's are always right up there in projected numbers and actual numbers.

So, it's a one-eachy deal. Either one can win. Neither one can win for you if you don't call the wind right. And, of course load right. Inconsistency in loading kills you big time.

My thing is you can get the same velocity from a case size somewhere in the middle of the 6.5x47 and a 6.5-06. As long as the case/bullet combo isn't burning barrels, then go with it. You may get a touch more velocity out of a .260 or another 6.5 wildcat. But, go too far with them and you won't have consistency.

Find what's consistent and stick with it!

 

[Casey Simpson]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Litz's opinion, I believe, is that the superior performer is a Berger .284 caliber, 185 VLD grain bullet, BC G7 .347 (BC G1 .659) @ 3000fps.
He would be the man on this subject. This is rocket science after all.

 

[mtn grizzly]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Bob, Chad, Casey, Sandwarrior and others:

Thank you for your insightful responses. GSSP asked the original question for my benefit. I am currently running a 47L in a tactical rig and its everything I could ever ask for. I actually run a very moderate loading that is a true 1/4 MOA @ 300 loading (123 Scenars @ 2900 FPS w/ Varget)

I am right in the middle of building a 6.5 hunting rifle, I would like to hit the 2950 to 3000 range with a 140 class bullets in a short action and don't feel comfortable pushing the 47L that hard - regardless of what its capable of.

Several accomplished shooters have made the comment that the 142SMK / 140 VLD / 139 Scenars like to run in the 2950 range. Terry Cross was using the 260 AI because he wanted to hit the 2950 range for that very reason and couldn't do it safely with the standard 260. It appears that some accomplished shooters actually do go with an AI version in search of target velocities. Maybe I am trying to accomplish something that is unreasonable ???

 

[Casey Simpson]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Have your bullets shipped to Superior Shooting Systems for Hexagonal Boron Nitride Treatment. Use Reloader 17 propellant. Use the Optimal Charge Weight load finder procedure. Run a long barrel. You'll get all you can get with these three maximum methods. Ignore anyone who says Rl 17 is temp sensitive. OCW makes that issue moot.

 

[mtn grizzly]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

I wish I had a dollar for all the times I have heard that RL 15, 17 & 22 are temp sensitive and that they will fail you in extreme conditions.

 

[BobinNC]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mtn grizzly</div><div class="ubbcode-body">Bob, Chad, Casey, Sandwarrior and others:

Thank you for your insightful responses. GSSP asked the original question for my benefit. I am currently running a 47L in a tactical rig and its everything I could ever ask for. I actually run a very moderate loading that is a true 1/4 MOA @ 300 loading (123 Scenars @ 2900 FPS w/ Varget)

I am right in the middle of building a 6.5 hunting rifle, I would like to hit the 2950 to 3000 range with a 140 class bullets in a short action and don't feel comfortable pushing the 47L that hard - regardless of what its capable of.

Several accomplished shooters have made the comment that the 142SMK / 140 VLD / 139 Scenars like to run in the 2950 range. Terry Cross was using the 260 AI because he wanted to hit the 2950 range for that very reason and couldn't do it safely with the standard 260. It appears that some accomplished shooters actually do go with an AI version in search of target velocities. Maybe I am trying to accomplish something that is unreasonable ??? </div></div>

mtn grizzly,

Not a thing wrong with having a goal, and if 2950 FPS is your goal w/a 139-142 gr class 6.5 bullet and a short action, then the easiest, safest, and cheapest way to get there is with a 6.5x284 Lapua.

It has a 66 grain case capacity vs 58 grains in the 260 AI. Plus better factory formed and correctly head stamped brass.

Yes, it is a better performer in a long action, but with Seekins WSM length mags in his Bottom metal you can reach 3.14" with a SA Rem, and some minor ramp/rail surgery and reach your 2950 goal at lower pressure, for longer brass and barrel life.

Another way of looking at this is:

Since hunting is the task, 700 yds is about the max range you can shoot at game, and insure good hit more than 90% of the time.

So:

Exhibit A: 140 Gr Berger VLD @ 2850 FPS

700 YDS Drop-4.5 MILS -15.3 MOA Drift 1.2 MILS 4.0 MOA 1900.6 FPS 1122.7 FPE

Exhibit B: Same Bullet @ 2950 FPS

700 Drop -4.1 MILS -14.1 MOA Drift 1.1 MILS 3.8 MOA
1980.8 FPS 1219.5 FPE

So your chasing 2950 FPS to yield an additional 80 FPS and 97 FT lbs of energy?? A solid hit with either one would make no difference on any game animal this round is suited for.....

Just some more pondering for you,

Bob

 

[Dagsta]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

Grizzly, I think you will find that Terry is and has been back shooting straight 260 for some time now!! I know he did some work with the 260 AI but every time I have been with him at a recent competition he has been using 260.

 

[sandwarrior]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Casey Simpson</div><div class="ubbcode-body">Have your bullets shipped to Superior Shooting Systems for Hexagonal Boron Nitride Treatment. Use Reloader 17 propellant. Use the Optimal Charge Weight load finder procedure. Run a long barrel. You'll get all you can get with these three maximum methods. Ignore anyone who says Rl 17 is temp sensitive. OCW makes that issue moot.</div></div>

+1

Not only does RE-17 have a burn retardant added to reduce temp sensitivity, it's mixed integrally with the powder itself instead of being sprayed on the outside of the kernels. That increases consistency of the powder.

However, even though they have a retardant added (sprayed on), RE-10, RE-12, RE-15, RE-19, RE-22, and RE-25 are all MORE temp sensitive than RE-17. None of these powders will fail you. They give good consistency at a given temp. The problem is going from cold soaked rounds to heat soaked rounds(those left in a chamber for a period of time after a lot of firing has been done.)

Also, nix the 6.5x55 idea. You said short action. And, unless you like taking your gloves off to single feed long seated bullets, this wouldn't really be a good hunting gun. 6.5 Swede needs a long action IMO. Then it's an outstanding hunting gun.

I haven't worked with the 6.5x47L, so I can't tell you what kind of velocities you could get. I do know that RE-17 will give you that long push needed when you have a long barrel. Someone threw the monicker out there that it was "specially formulated for the WSM/WSSM cartridges" I found it to be just the opposite. It doesn't work for me in my .25 WSSM, 7mm WSM or .300 WSM. But it works fantastic in my .243, 6mm Rem, .257 Rob, 7-08, 7x57, .280AI, .308, and 30-06. See a pattern there? Any medium to 30-06 length case with a .473 base will do well with it. Come to think of it, it does get kind of funky with my 6-.284 too. Stick to standard diameter cases, and you'll be fine.

 

[rymart]

Re: Is the 260 AI a logical choice over the 6.5x47 L?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hondo64d</div><div class="ubbcode-body"> No doubt higher pressures in the 6.5x47, but don't you think the small primer pocket allows the case to handle the higher pressure better?

John </div></div>

+1, + the smaller diameter flash hole in the 6.5 x 47L.