243 Ackley Improved Problems

[yawn]

I think the funnest thing about the nosler 280ai is how its changed in the eye of some comentators over the years. In this old thread the theory was that the nosler version was .014 Shorter.
https://www.longrangehunting.com/threads/280-ai-controversy-explained.118623/

Now the claims are that it is .014-.016 longer? A truly magic chambering.

Iv done enough measuring of chambers with actual gauges to have a solid body of data and this magic .014 difference in either direction is yet to show its face.

Though my process was different my results mirror theses guys
https://gunsmithtalk.wordpress.com/2012/07/17/280-ackley-improved-emperical-headspace-test/

 

[Tidus56]

Thanks for the input guys, I will add I am not looking to start a ****ing match on here. I am simply looking for how to head space my 243 AI properly. My current 243 AI barrel shot amazing during fire-forming, so putting this new barrel on and starting with new Lapua brass I am looking to do it right so fire forming lets me knock down p-dogs at range. I have asked two gunsmiths and both didnt know the answer. I have a 280 Ackley barrel on its way as well. I specified that I wanted the Nosler version on both the head gauge order and the barrel order. Plus I sent in dummy rounds, so I am sure I can get it right. Thanks again guys.

 

[J E Custom]

If your posting about me, everything I posted is true I'm just surprise JE didn't mention those 280AI in Nosler and Sierra manual and that's what my non Spec 280AI is. Those loads been in Nosler manual since mid 90's. I think it would be interest if JE post reamer print on the 280AI he build before spec

I dont single anyone out when we have a discussion if at all possible.
I was just commenting on what I know after chambering many AIs in all calibers. I have always followed PO Ackley's recommendations and have never looked back. The results have always been steller.

When nosler first came out with the "New" 280 AI SAMME cartridge, I was still chambering the Ackley method. and was perplexed by the changes they had made in the original 280 AI cartridge so I talked to dave kiff about it and he explained the hole deal. (There is a post on this site that he did on this subject that explains it in his words)

He built the reamers for Nosler and discovered that the reamer drawings had been altered after some of his clients started having trouble with case head separation. I don't know if it was his fault or nosler had it changed for their own reasons (I don't care) but i was glad to learn about the difference before I used the new AI headspace gauge.

I have since done both chamber and haven't had problems as long as the correct brass is used for ether.

This picture posted by another member shows the difference between the original 243 and the 243 AI case and clearly shows the recommended .004 thousandths crush fit of the AI chamber.

Maybe these guys didn't get it right, but according to the drawings, there is a 0.004" difference in dimension (shorter on the Ackley) from base to neck/shoulder junction. That 0.004" would be to insure that one headspaces on the neck/shoulder junction when one chambers regular 243 Win brass. The extra case volume is accomplished by blowing the shoulder forward and removing a little taper.

I'm not sure why everyone gets upset about these differences because the gunsmith has the final control and responsible for the chamber dimensions and should confer with the owner on which one he wants.

I just to explain the differences so the owner can make the decision for which way he wants to go. and the one that will give him the best results.

J E CUSTOM

 

[J E Custom]

What does the bolt feel like when you try to chamber a standard .243? if it feels as if you run into a rock wall maybe you have a tight neck chamber. If the bolt almost closes and is hard to cam over you probably are bumping against the shoulder. I would have a gunsmith check it.

With only .004 thousandths compression (Just like PO Ackley recommended) If it is SAMMI factory ammo or cases, the amount of effort is almost unnoticed unless there is something wrong with the chamber or it is not SAMMI. The reason for the compression is to hold the cartridge in place and minimizes case stretch while fire forming. the only way to damage a chamber it to force a head space gauge in to a chamber. the head space gauge will not compress like the brass cases will, and force is the enemy of all things related to gunsmithing.

J E CUSTOM