6.5x55 AI or 6.5-06 AI help me choose

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webberwood

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I have a Tikka T3 chambered in 6.5x55 Swedish that I’m considering either having the chamber modified to an Ackley improved or possibly rebarrelling to 6.5-06 AI. My ultimate goal is to be able to push 140 grain Nosler Partitions past 3000fps. My current barrel is 22” so I’ not sure if it’s long enough to fully utilize the additional case capacity of the ackley chamber so I may have to throw a new barrel on either way.
 
Go with the 6.5-06. Even with the Ackley Improved, you would really have to push the 6.5x55 to get where you want to go. I have a Mauser with a tight chamber and 24" barrel that will send 140 SGK at 2,800 with the standard Swede. Don't think you will get another 200 fps with the Ackley. For whatever reason, the SAAMI MAP for 6.5-06 A-Square is 65 ksi. With it's case capacity, QL says you can exceed 3,000 within that spec.

PS: The suggestion of 6.5-284 Norma is a good one.
 
Hornady new manual #10 has loading data for 6.5x06 with 140gr in the 2900fps range. They use Shilen 1/8 twist barrel @ 24". I shot the 6.5x284 Norma OAL 3.228".

I shoot 280AI and I've been looking at this and going to be my next build.

https://westtexordnance.com/6-5x280ai/

Your magazine isn't going to be long enough but may want to give them a call. I think you get to over 3000fps with no problems.
 
That is going to be difficult from a barrel that short.

And your barrel life is going to be short. I have a 6.5-06, I shoot 140 SMKs at ~2900, but have a 26" barrel, and my barrel life is not that great, in fact I am due for a new one with about 1200 rounds through mine.
 
OK, I'll play. First off, you absolutely need a 24" barrel, unless, of course, you can settle for a longer barrel and can live with 26" or more. We all know darn well that the 264 Winchester magnum is too much of a good thing, vastly over-rated, it basically duplicated the already great 270 Winchester in barrels of the same length, and with much shorter barrel life.
I have been interested in the 6.5mm cartridges for while now. The current trend, that revolves around the 6.5 Creedmoor is actually quite sensible, as are it's closest rivals, that is, the 260 Remington, and perhaps best of all, the 6.5x55mm Swede.
If you want more performance than these can offer, you have to be willing to sacrifice some barrel life. For a target rifle, it's not worth it. For a hunting rifle, it's another story, and I think that the trade-off may be worth it to a point. And at the point where it's worth it on one side of the line, and not worth it on the other side of the line, well, it seems to me, that the 6.5mm cartridges that are closest on the edge of being worth it, are those that have the approximate capacity of the 30-'06. Thus, the 6.5-06 is perfect.
So also, except for one consideration, are a few others, notably, the 6.5-284 Norma, and for those that may be too young to remember, the vastly under rated, 6.5mm Remington Magnum. Both if these will work in a shorter action than the 6.5-06, if it matters to you. But, the opportunity that continually presents itself to the 6.5-06 shooter, i.e., to resize commonly available, often, free, once fired 30-'06 brass, why, it must not be underestimated, in my book.
So there, I say it, the 6.5mm-06 is the best bet, as far as the OP was asking about, and, again, there is that line.... and to go with the AI verison, would be on the wrong side.
And, within the context of this thread, the closest comparison, a rival, yet in a different caliber is the 270 Winchester. Webberwood you are asking, to match what my 24" barreled model 70 Winchester, in 270, routinely does. I expect 3,100 fps from 140 grain bullets. I've had them up to 3,285fps, admittedly with shorter brass life. If you have a long-action and simply must have a 6.5, then you know what I said. Otherwise, just be happy with the Swede, it's one of the nearly perfect cartridges ever.
Remember, it's all just numbers; why care so much about numbers?
 
I have the 6.506, I cant push 140 grn to 3000 witbout pressure signs.
If I were you, (O P) and just had to have it, Id chamber the new barrel in 6.5-270, less trimming, and more neck tension giving velocities regularly over 3000 without pressure signs....
 
My current loads for the t3 are pushing 140 gr Nosler Partitions at 2900 fps. I’ve been able to push it as high as 2950 without any pressure signs. I’m well aware that these are exceptionally high numbers and pressures but it works wellin this particular platform. From what I’ve seen the standard 6.5-06 doesn’t offer much more than what I already have which is why I was considering the ackley version.
This is strictly a hunting rig so I have a few parameters in mind.
1. Barrel length should be limited to 26” preferably 24”.
2. The action on the t3 is easily changed to long medium or short action. I’d rather not have to modify/change out the bolt face to accommodate magnums.
3. At least 3000fps with a 140
4. Readily available quality brass, I don’t mind fire forming
5. Cartridge must fit and feed in my current long action magazine. Limited to ~3.295 OAL
 
If you are shooting 6.5x55, you are way over pressure. I've pushed that round pretty hard in a couple very strong rifles, and I'm nowhere near that. QL says you are hitting 70 ksi to get 2,950 out of a 22" bbl. Stop!

Note the posts for 6.5-06, which has much higher case capacity and SAAMI MAP. Folks are topping out at 2,900. Yes, QL says you can hit 3,000 with 6.5-06, but that never trumps real world data. In any case, max COL for 6.5-06 exceeds your stated mag max.
 
Your loads are way over pressure, you are never going to make that sort of velocity in any 6.5 Swede case variant regardless of barrel length, but if you go with a 29" barrel, you are more likely to get there.

Bud's of mine have shot out 264 Win Magnum barrels in less than 900 rounds. Might have been 700 to 800 rounds. By the time you test your loads and establish your zero's you better have another barrel on order, because the old one is about to go!
 
I'm not suggesting that anyone should ever try to duplicate these numbers in their rifle, I was simply pointing out that the standard 6.5-06 doesn't offer much more than what I'm currently using. For the record there are several T3 owners out there generating similar velocities with a standard swede.
 
Sounds like cost-per-result isn't your first concern so if that's a project you want to do just for giggles it's absolutely your perogative. I had 6.5 Gibbs back in the day, and I quickly got over the whole blown out wildcat thing.

I, like others here, admire the 6.5 284 Norma but advise this, you may have feeding issues. The short, fat case with its rebated rim has a significantly different geometry when loaded in a double stack magazine. The follower and/or feed rails etc. may have to be modified and that needs to be done by someone very competent to get reliability.

IMO, one of the beautiful things about the 6.5 caliber, is that the bullets are sleek and efficient in flight. They "don't seem to care" if they're not launched at blistering speed, and seem to perform much better than they have a right to when they arrive on target.

To address the op more directly... no your 22" barreled won't realize a significant gain to justify the expense and trouble IMO. Neither would a rebarrel IMO; Ackly chambers just don't produce big gains unless you also increase load pressure to the ragged edge of max.
 
I had my 6.5-06 long throated, where a 140gr SMK is seated to base of the neck. I've gotten 2935 with 140 Hornady Interlocks with the old generation H4831. I use 25-06 Brass.
 
hooligan1 said:
I have the 6.506, I cant push 140 grn to 3000 witbout pressure signs.
If I were you, (O P) and just had to have it, Id chamber the new barrel in 6.5-270, less trimming, and more neck tension giving velocities regularly over 3000 without pressure signs....
Click to expand...

I also have a 6.5x06 and a 6.5x55. The suggestion to go 6.5x270 was told to me but after I had the 06 version. To use 270 case's, as I recall, I needed to re-size and then trim case's. That means that I would have more nect if I'd used the 6.5x270. I guess it's a point. One thing I found with the 6.5x55 is that in a modern action, mine is a mod 70, you can scare the heck out of the 6.5x06. Something that would keep me from the 6.5x270 is there are a lot more 280 Rem, 30-06 and 25-06 case's to make rounds from than 270's. A 6.5x270 would require 270 case's to get the longer neck. The 6.5x284 s about in the same situation with regard to case's. Then I think the only case you can size down to is the 284 case. Another thig I think might be the action, most 284's were on a standard case, 308 length? If so, it probably won't let you seat the bullet's to the lands, if that matter's. I'm pretty happy with my 6.5x06, super cartridge! Thing I did wrong was to heavy a barrel contour and a bit to long a barrel. Heavy magnum barrel 25". I have carried it hunting and it's fine but heavy! As I recall it's about 9# without a scope. I don't understand the reason for going AI with either of them. I think with a lot of people it's just because. I've got both of Ackley's book's and it seem's to me he said his best was the 250 AI. The rest it seem's he didn't get enough out of for all the extra powder.
 
The magazine on the T3 is a "single stack" design so the feed issue may not be a problem with the 6.5-284. I'll have to look in to this cartridge a little further.
 
The 55 case is six thou larger than the .06...can be done, but you probably already know you'll have lousy brass life unless you neck-size only, it'll get you close to what you say you want, but at the expense of barrel life as mentioned.

What's the end "game" - and since rebarreling is an option, you've got a lot of them- particularly on the long-action Tikka.

The 6.5-.284 Norma is a great round no doubt, but more of a 1000 yard competition or specialized hunting...and with the same downside of low barrel life.

Consider that rather than the overbore 6.5, the .284 Winchester will give you the same 3,000 fps- give or take- from a 22" barrel. With identical weight, 140 grain Partitions your downrange stats are a bit less for the 7mm due to the higher BC of the 6.5- but not dramatically so and at much greater barrel life. On the long action, if you ever wanted to push heavy VLDs you'd be able to do so; something that might be an issue with a .280 Rem.

Anyway, best to be more specific with your application if rebarreling is the route you're going- including the relative importance of barrel life/annual round count, in order to get the most relevant recommendations.
 
Your loads are way over pressure, you are never going to make that sort of velocity in any 6.5 Swede case variant regardless of barrel length, but if you go with a 29" barrel, you are more likely to get there.

Bud's of mine have shot out 264 Win Magnum barrels in less than 900 rounds. Might have been 700 to 800 rounds. By the time you test your loads and establish your zero's you better have another barrel on order, because the old one is about to go!
Click to expand...
I have literally shot 264 Win Mags since I was 7 years old. I have 4 of them. Winchester factory barrels are good for 800 to 900 before the groups start to open. I would say they are shot out by 1100. I have always rebarrelled with Lilja stainless. 2 26" barrels, 1 28" barrel, 1 30" barrel. The highest round count Lilja is at around 1100 and it is still 3/8 MOA.
If it takes someone 700 rounds to zero and load develop, they probably should learn how to do both properly.
 
The 6.5-.284 Norma is a great round no doubt, but more of a 1000 yard competition or specialized hunting...and with the same downside of low barrel life.
Click to expand...

You are going to have to offer me some evidence of short barrel life. My 1k bench 6.5x284 has at least 1500 rounds on its Lilja tube and is as accurate today as it was at 100 rounds.
I guess my Savage Predator in 6.5x284 has 1100ish on it with no signs of barrel going south.
 
The point of high BC bullets in 6.5 caliber is the ability to keep muzzle velocity moderate while retaining speeds down range. Without excessive barrel wear.

You can get near 2700 fps with a 6.5X55, 6.5 Creedmoor, or 260 with 147 gr bullets from a 22" barrel. They will still be over 1000 fps out to almost 2000 yards.

I just don't see another 200-300 fps as being worth it.
 
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