I don't feel that is completely necessary, especially if his chamber is not on the "tight" side. While a clean-up pass is not a bad idea in any way, at this point I do not feel it will remedy the situation. The way I interpret the issue is a powder/case fault more than erratic ES or LR accuracy.
Like I said, a cleanup pass is not bad, but not where i'd be looking right now.
just my .002
"I, however, view ethics as an individual decision. My ethics are mine - and I won't explain or justify them to anyone else. I seek nobody's approval, just that of my own conscience. "
Just doing a measurement of the necks could tell you if turning is necessary... if the variation in neck wall thickness measured at several points around the neck is larger than +/- .002", turning the necks might help.
A 338wsm wildcat that I have did not shoot good until I bought high-end brass... the Winchester brass I was using had horrible case neck variations after I expanded up to 338 (and it was not great before expanding). The neck wall thickness varied between .012" and .018" in some of the cases. That is simply horrible. The new high-end brass, even after expanding, had a max variation of .001", and that was comparing every brass in two different boxes. Max thickness was .014 and min thickness was .013. So turning was not necessary... And it made a huge difference in accuracy.
And, it was a pac-nor barrel that didn't shoot very well until I switched brass. Now it shoots amazing. The gun is a true shooter.
Although, But my first guess is that brass with a much smaller .243 neck would not have the same problem... but five minutes with a set of calipers would confirm one way or another.
and measuring the outside diameter of your fired cases, and comparing with a loaded case could tell you if you have a tight chamber. Which I guess is more of a possibility with your AI if the chamber was cut on the tight side. I'm not sure if AI chambers are known for tight neck dimensions ???
Although, with all of that said, I would tend to agree with Outlaw6.0 that your case necks are probably not the problem.
The reason I'm chiming in is because measuring your brass is free and really does not take very much time to eliminate as a problem source. Being very methodical to eliminate every potential source for error is the only way I've figured out how to make a couple of my rifles shoot well.
Outlaw also made a very true statement that there are no guarantees with these rifles, however, based only on opinion, I just can't imagine a 243 AI put together by a great gunsmith would not be able to shoot better than 1/2 moa. I also think you are right on track to expect that kind of accuracy out of your rifle, so keep on trying!
Thanks for all the help I have received from the great guys on this forum. I did get good groups using RL19 but was really pushing the limit. 95gr bullet behind 48.5gr.......................I was under the impressing that you could go 10% over standard .243 loads. Was running some hot loads.................I did stop off at the gun store to find that they had just received a shipment of powder ........bought 2lbs of H4831SC Im now shooting the 90gr Ballistic Tip and was very encouraged shooting two groups that went right at .545 the bullets were seated .020 off the lands and this weekend will be starting at .035 and working back to .000 in .005 adjustments..................Im very hopefull that I just might be able to get below that .500 mark that I have never done before.
I have heard that the .243AI works great with slower powders and will be trying some H1000 dont think I will have to worry about over charging as when I tryed to put in 52gr in the Ackley .................Well no way. So I did load some with a starting load of 50.0.
Others have sugjested RL 22 or RL25 I did see that the store had some IMR 7828 SSC.
I ran into a great guy out at the rifle range monday that was also shooting a .243AI He gave me some 87gr Vmax and said that they were murder on Marmonts...............................He offered me any help if I need it and gave me two lbs of H4831SC that he had no use for
I have a new can of 8lbs of H4350 if anyone wants some.................i only use 1080 gr. of it and will make anyone a deal..............I bought the H4350 about two weeks ago.................
Thats great Greg, I figured if you slowed up your powder a-bit it you would see better results.
The 243ai really shines with the 105-107 grain bullets going over 3050, for really long range shooting. When Len was shooting his 243ai he was using H4831sc if I remember correctly, as was I in my f-class gun.