243 Win. vs. 243 AI

[Pawildman]

I've been considering changing a 243 Win. to 243 AI. I'd like some opinions on whether I should go ahead and do this or not. What would be best--rebarrel or rechamber? If I rebarrel, who do you recommend for the barrel? Twist? I would like to shoot 85 gr. bullet.
The possible patient is a 70's 700 BDL with factory sporter barrel.
Comments, guys???

[savagescout]

I am sure you have seen thiswebsite.

http://www.6mmbr.com/243Win.html

I fought this for a while and decided for me .243 win would be better for me as a predator rilfe. good luck in your choice.

[James B]

Going with the AI is never a sure thing as far as velocity gains but will always help case life. The only down side is that sometimes you just end up burning more powder to reach the velocities you had before the conversion. This does not happen often but it can happen.

[biscuit jake]

Good point. In the .244 class, I would go 6mm Remington

[stalkingbear]

One of the best things about ANY ackley improved cartridge is the fact that it's a simple rechamber and also you can fireform by simply firing factory cartridge in ai chamber. All of the ai cartridges headspace on partial shoulder of factory contour except for rimmed cartridges of course.
As far as twist-1-11 should be just about perfect for 85-90 gr bullets. Another round to seriously consider is 6mm-284. The main thing to check for is if your rifle action will be long enough. Because of the rebated rim,case head size is same as .243-.473 and simple rechamber is all that's neccecary alto you will need to get 6.5-284 brass and neck down. I've had great luck with and use these barrels-lilja,hart,krieger,shilen,and walther lothar.

[jeepkid]

I am going to do the .243 AI. A little better velocity, better case life, and a little different then what everyone else has. It would be a better idea to go with a faster twist barrel then you think you will need. I am going to do a 1/8 just in case I want to shoot VLD's. If you know you will never shoot VLD's then a 1/10 will probably be a good choice.

[Pawildman]

Been doing a little reading on this....What are you going to use for parent brass? 243 Win.? Some of the articles I've read seem to indicate that the 243 fireformed brass ends up with shorter than desireable caselength in the neck area. There is aprocedure to use '06 brass that seems to get away from this bit of a concern. Could the custom barrel not be ordered with this in mind and the cases (243 Win.) be trimmed if necessary to fit the new chamber neck dimensions, or am I assuming wrong??

[jeepkid]

I haven't heard about the cases being too short. I am going to use regular .243 brass, most likely Lapua.

I would think if the .243 AI cases would end up being too short, then all the AI chamberings would be too short...

[driftrider]

I don't think that case length or neck length will change at all since the neck remains unchanged during the fireforming process. The length of the neck only becomes an issue when resizing the neck to a different caliber (where the neck will get longer when you neck down and shorter when you neck-up the case). In the case of a Ackley Improved case the only change is to the shoulder angle, typically to 40 degrees, and the case taper which is straight or nearly straight, but the point where the neck meets the shoulder remains the same thus the neck doesn't change. This fact is why ammo in the parent (non-AI) cartridge can be safely shot in the AI chamber and was exactly what P.O. Ackley had in mind when "Improving" the various cartridges.

I suppose the only way the neck could change is if the chamber was really sloppy and/or headspace was excessive, but a properly cut and headspaced chamber shouldn't cause this problem IMO.

Good Luck,

Mike

[Pawildman]

Here are some things you may want to look at....on the web, type in ".243 Ackley Improved"......also look at "Fred the Reloader". Gets a little involved....