The barrel maker is very keen on doing 243imp. Before I take the leap, I would like to check if my sako will feed 243imp. Would anyone be kind enough to mail me 4 sized, unprimed empty cases for me to check? If so PM me for my address.

BTT

1894, I know this is absolutely none of my business, and I know your smith would like to turn the new barrel into a .243 AI, but I still just can't help myself. The .243 is already pretty overbore as it comes from the factory. That means there will be comparatively little velocity to be gained by improving it. Add to that extra hassle having to fireform cases, shorter barrel life and lower resale value, more difficulty getting hold of good dies, possibly having to anneal cases after fireforming etc etc. Your choice, personally I would not bother.

In the early days of my rifle buying career, I thought mods like improving cartridges were the cat's meow. These days, I realize there is little to be gained other than a lot of extra hassle. If you want a big case, get a big case. I found myself constantly approaching the pressure edge (no load data available at the time), to achieve the velocities that had been advertized. For what practical gain?? Besides, if anything, the .243 is a tad fast for Roe, no need to make it even faster.

Sorry that I can't contribute the .243 AI cases, I could have provided some .280 AI samples.

- mike

Mike,

Yeah I know!

Meat damage is not an issue. It's just that some report some pretty good gains with the AI version and I thought I would merely hunt with the fireforming loads and then put together the AI loads. The finished rifle would weigh 8.5lbs with a bipod and be rather a wonderful chamois number able to fire factory ammo at a pinch...

Then again it'd be pretty good as is. Too much time for thought!

If you don't have your empty cases yet, let me know and I can probably help....I have two .243 AI rifles and a lot of experience with them....George

I can see the point about wanting to possibly hunt chamios with the gun - in spite of the fact, that your 6.5x57R is about as perfect a chamois caliber as you can get. But don't forget, the actual improvement you can realisticly expect from improving the .243 may lie below 100 fps. I.e. you are looking at maybe 3100 fps vs 3000 fps for the standard .243. Big deal! Ain't going to mean much in real life.

OK, ok, I'll crawl back into my cave now...

- mike

Adam,
After I received your e-mail, I replied to you with a long explination about the .243 AI. I received back an error message saying something was wrong with the address......If you give me an exact address, I'll try again......You can send it to my private e-mail addy......
George

Adam: I have a good friend with a .243 AI that is nothing other than a standard L579 Sako with the factory barrel rechambered. Feeding is perfect, and I don't think anything modifications were necessary to the feed rails or magazine.

It is, hands down, his all time favorite rifle, and he's a gun dealer who owns and has owned dozens of rifles personally.

Stonecreek,

It's funny but everyone who I've spoken to who has had a 243AI is head over heels in love with it....

GSH I've PMd my e mail address

. . . . and on the other hand, I own four .243's and am not considering making any of them into an AI since I'm perfectly happy with them the way they are. If I had a "sloppy" chamber or headspace issues with one of them, I might very well go ahead and make it an AI in the process of curing a problem, but otherwise, I don't find it worthwhile enough to be enticing.

Adam,
I started using the .243 AI about 15 yers ago for Groundhog hunting out to about 500 yds. or so.....As a rule, I don't particularly like dual purpose rifles because they end up being only fair at some things and not really great at anything...NOT always, but usually...Having said that, I'll try to help you as much as I can......Now..to try to answer your questions....
You might get better accuracy because of the new match grade barrel but not because of the .243 AI although it is just as accurate as the .243 Win. You will get a useful increase in velocity, especially with the 25" barrel..
As to twist....a 10" is as fast as you will ever need and will certainly stabalize the 100 gr. bullets...I think its important to use a twist that will handle the heavest bullet you intend to use but there are some "down sides" to going faster than you actually need....I have mine set up with a 12" twist and I use the 70 gr. Nosler BT at about 3800 fps in a 26" barrel...That twist will stabalize 85 gr. bullts just fine but that as heavy as I have tried....
I expect the .243 AI will feed fine but it depends on just how much the body is blown out...Since its a wildcat, there are no exact specifications and there are a lot of different reamers made for the .243 AI...Throat length is another consideration....You will want it long enough to handle the heaver bullets but short enough to get the lighter bullets up close to the lands and still have plenty of bullet (purchase or grip) in the case neck...
As far as fire forming and shooting good groups with fire form loads...that depends on the load and how the chamber is headspaced...The headspace needs to be tight on the new unfired case when fire forming...That is to say...a light crush fit....If it isn't, then you will need to seat the bullts in the lands about .010...otherwise your cases will stretch at the back of the case near the head and will form a week area tht could and probably will sepetate after a few firings....I have several Ackley chambers and I have learned thru painful experience that the chamber needs to be tight with fire form loads...
Again, accuracy will depend on the load and just how the chamber is set up...I don't usually get my best accuracy with cases that fit tight in the chamber....
Over the years, I have found that the .243 win. and the .243 AI are hard on barrels....I would say that that you could expect a good 700 to 900 rounds before the barrel begins to show a decrease in accuracy and that depends on just how hot your loads will be...your experience may vary from mine......
I like to use a fast burning powder like H-335 for fire forming because I get a much better formed case and then I use H-414 for the 65 to 75 gr. bullets in the .243 AI case.
I hve not tried bullets over 85 grs. in my 243 AI so Ican't offer you much help there....There is a wonderful article in the April 1999 issue of Varmint Hunter Magazine by Steve Timm on the .243 AI and he gives chapter and verse on fire forming, load development and the best powders for bullets up to 85 grains....If you are not familiar with it, you can order it from the magazine at 605-224-6665....
Now if you still want some cases to try, let me know and I'll try to send you some...No charge....Good luck...
George

Very many thanks for this info. I think someone in the UK is sending me cases. May I ask what velocities you got with the 85gr and with what powder?

Dave,
I believe that you will find H-4350 SC will probably be one of the best powder choices with the 85 gr. bullets...
Start out with 46.0 grs. in the .243 Ackley Improved and work up cautiously. 47.5 grs. will be about maximum and velocity should be in the 3500 fps range (maybe a little more) with your 25" barrel....I have found H-4350 SC to be the very best powder (for me) in this bullet weight range in both the .243 Win and in the AI.....With the .243 Win (not the Ackley) 43.5 grs. with the 85 gr. bullet has given me the very best groups in all of the .243 Win. rifles I've owned over the years.. Powders vary from one lot # to another so be on the safe side and start out low and work up gradually.....Good luck......
George

That will be a considerable increase!

Currently I use ordinary H4350 under a Speer 85gr BTSP. 45.5gr (0.5gr under book max)gives 3,200fps average and great accuracy.

Many thanks for all this.