I own four 6.5X55 rifles. One sporterized M38 Husky, two M96 military rifles and a custom 6.5X55 on a Turk Mauser action with a Swedish barrel. I am thinking about an AI 6.5X55 and would like information about this cartridge and it's performance. I have a couple of actions and I also have a new 6.5X55 barrel and I need to build something. Help please!!

Do a search here for a 6.5X55 BJ, which is a version of an improved 6.5 Swede. It's one of those calibers I keep meaning to get around to. - Dan

There is also the 6.5 Arch which is covered pretty extensively in Ackley's book.

If you want more oomph why not opt for a 6,5-284 ??

It will clean your excisting chamber up and give you 200f/s extra with a 140grs bullet. I would also have it freebored a bit so you can set the bullets to the bottom of the neck only.

The Swede is funny like that, you have to have a long action but you do not use more than 80% of the lenght in std chambering.

If you where to change your barrel instead of just rechamber it I would also look at the 6,5-06. Nice round and easy to make. Didn't A-Square Saami approve the 06 ?

I have found the 55AI finichy and does not give you much edge over the original one. You get maybe 4 % extra powder volume-nothing to get excited about.

On this side of the pond the 6,5-06 is perhaps the the most popular wildcat of them all. A-Square ammo is not available.
The 284 is picking up

The AI cartridges are minunderstood at best and dangerous myth at worst.

Let's remember, there's no magic in rifle cartridges. More powder = more velocity. There's no magic case that gets you more for less. When increasing case capacity, the larger you get, the less efficient the cartridge gets. Changing to an AI cartridge only gains a couple of grains of powder which equals out to at best 100fps, and often times not even that.

On the dangerous side, there are those who will tout 300fps difference with the AI. What we have here are overloaded cartridges at dangerous pressure levels. AI chambers tend to be well made so the typical "pressure signs" usually dont present like a standard factory rifle chamber. So, these AI "experts" push the velocities up until they see some "pressure signs," but the problem is that they exceeded normal pressure several grains ago.

If you are looking for an increase in performance, you wont get anything significant. 100fps will never be felt by the deer you shoot, nor will it significantly cange your trajectory.

So, with all that said, you would think that I'm not a fan of the AI...Not true. I just dont like to see them abused or talked about incorrectly...read unsafe.

In fact, the AI is a great idea for the sporting rifle. What it does have to offer is a huge increase in case life. Accuracy can sometimes be improved as the AI tends to be a slightly more concentric chamber than the factory chamber.

With an AI chamber, you will really have a hard time wearing out your brass.

So, here's the trick with AI's. First, you need to be content with the ballistics of the base cartridge, in this case the 6.5x55. What's not to like about that one? It's a great round as it sits. In a modern rifle, you can bump up the pressure a bit into the 52,000 psi range of the .308 Win. (SAAMI specs are 46,000 psi)

Now, we add the AI chamber and keep everything in the 52,000 psi range and you'll see a slight increase in velocity over the standard modern gun 6.5 loading, but you'll have LONG brass life.

Guesstimate your pressure with a chronograph. Compare the 6.5 AI to the 7mm-08 Rem to gauge your pressure. The 7mm-08 will push a 140 grain bullet to 2800 fps out of a 24inch barrel. The 7mm-08 has a slightly larger bullet base, so there's more to push against, so this should give you a good yardstick for gauging your 6.5 AI. If you ever push much past 2800 fps with your AI, you can be sure you're just about at maximum. Even with the increased case capacity of the AI, I would stop my loads at 2900 fps if I were seeking absolute maximum velocity, even if I dont have any "pressure signs" as the AI chamber will typically not give away much in the way of pressure signs.

Not bad for a rifle modification that runs well under $100.00.

Just my two cents