Have been thinking about doing a custom or semi-custom rifle build. Now I'm not near as knowledgeable as most
here, but was wondering if doing an Ackley chamber is worth doing? I know the benefits of the increased case volume and less case stretching = less case trimming, but generally speaking are doing A.I. chambers worth the time and effort? The calibers I am looking at are the 6.5-06AI, 30-06AI, 338-06AI, and the 375 H&H AI. Any thoughts or input from those with experience would be welcome. This is something for future ideas and reference as my wife just got the word of having her hours at work cut by 40% and her mom is coming to visit for 6 months WDTSHTM and I need something to keep my mind and spirit up and focused to help get me through this.
Thanks Guys

my thoughts on your list:

6.5-06 i probably wouldn't AI myself, as you have plenty of displacement to make good things happen downrange as is.

30-06 and 338-06 i would like to run either in AI. they can use the extra poop.

.375 H&H i'm undecided about. if the ai version fed well from magazine, i can't see a downside, but i suppose it depends on your needs.

just my $.02

375 H&H of those listed with the 6.5/06 next.

I personally like the 223, 250 Savage, 30/30 and some of the smaller x57 cases to Ackley.

and 22/250

If you are going to build a custom rifle and don't mind the extra hassle of forming brass then by all means go with the Ack. I would build either the 6.5-06 or 280 Ack. One other you may want to think about is the 257 Ack . I love my Sako i had built in this cal. This is one of the best improved round you can chamber for. Accurate , flat shooting and kills extremely well when load with the Nosler Part on any game up to Elk.

I own two '06AI's and to me the biggest benefit is being able to maximize the new longer, heavier, higher BC bullets like the BT and Accubond. I also own a 6.5-'06AI that is pushing a 120 BT at 3200'/sec. I use this rifle as my primary deer and Antelope gun and the ballistics to 400 yards are impressive. Both rifles give a 150'/sec speed boost and extended case life and reduced case trimming. I would never consider the 375 H&H as an Ackley candidate as the mild load I'm using now is punishing. That said if you can take 5000'lbs of ME then go for it. PO Ackley stated the 257 was the most efficient caliber for his chambering...'nuf said. Regards, Rick.

After getting, using and keeping three improved chambers I have concluded that they are a waste of time if being practical matters most.

However this is how men behave. I have owned three Corvettes also. Again an impractical decision.

In terms of the universe or real money an improved chamber is not a big deal. Its up to you.

Now here is a picture of what a real car looks like. One just like this was stolen on me but I put 200K on it for a decade. 429 360hp, air etc. What a car!!!!!!

Ai is for lovers. When a guy has a love affair with a ctg, he is always looking to sweeten the pot a little more, then and only then, do the AI's.

With the .375H&H I have just not seen the need for more, there for I would particularly want one and would steer away.

If you are talking about the .250-3000, heck yes. This is one I enjoy more than all others in a .250, the .257 Roberts in and AI? I have and use more than any others. But I still feel that the .250-3000 AI is your best bet for the money. I feel that the 6.5-06, if I was going to do another, I might just try the old RCBS chambering, I would let the folks at Huntington do the work, but only after I shot out the barrel I have now. It's a good tube and shoots better than it should.

I always thought that if you are going through the trouble of handloading anyway, why not go Ackley?

Less trimming, more powder, fireforming is still out shooting, so what's the downside?

Some ctg's just don't gain any thing that warrants the cost of dies. I like the ones that see a noticeable gain, but the other ones, I just don't see the added costs. Then again there are other wildcats that I like and use frequently that have nothing t do with the ACKLEY name.

The biggest gain for the no trim is the 35 degree shoulder. That is a truism that I have never seen violated.


I have yet to see any difference or gain in the 40 degree over the 35 degree shoulder. Feeding is another story.

What nobody mentioned was the .25-35 AI. No other ctg has ever gained more than this ctg from the AI chambering.

What a nice ctg. I have the reamer for this one also. I only buy a reamer for the ctgs I like and use the most.

In other words, my investment in AI go far beyond just having one or a few, I find that vary little surpasses the one I invest in.

Take your guns out to Joel Ackerman. A 100 miles west of town. I have had 2 done by him and they shot bug holes.

My favorite Ackley is the .257 Roberts AI. I'm on my third one. Use them for (gulp) ground squirrels! No rhyme or reason to it, the first one I had was an original Ruger M77 Round Top with open sights that was rechambered. That thing shot so well I nearly fainted.

Just this month I found the new Barnes 80 grain TTSX at 3,485 fps is good for varmint in the lead-free area, like feeding them into a blender. Who'd have thunk it?

I have a couple of other Ackley chambers, but they are too esoteric for general discussion. Today there are so many good factory cartridges "improving" them is more for those wishing to scratch the curiosity itch, or desire for something unique.

Note that most who cited AI carts here were of serious case taper in their original form.

The three you listed all fit the AI bill.....

I was really looking at a 6.5/06 AI, have since scored a .264 tube, but I really liked that one.

Good luck on your choice.

FWIW...

Had a 257AI and a 7x57AI. My 7x57AI picked up nearly 4g case capacity...which shows up on the chronograph. Liked those.

I like the 280AI. I like it a lot more now because Nosler makes cases. It is the easiest way to get the max potential out of the 06 case...

But six months is a long time....imagine a guy could come up with something interesting necking that Nosler case up or down...

In all of the above posts the only consideration of AI has been velocity improvements or the trouble of fireforming.

The real reason to AI in my understanding is because of the change in the way that the firearm will handle pressure. It makes it nearly impossible to hurt yourself handloading. The only way that you will understand this is by getting PO Ackley's Manual Vol I. Read it about three times. You will get it. Then go to:

http://shootersforum.com/showthread.htm?t=5813&page=2

Scroll down to the eleventh post by David White and read what he says about backthrust.

I have a .338-06AI and would not trade for it. It is an anything killer out to 500 yards for all of North America. Very little recoil. I shoot 250 gr bullets ~2550MV. It has less recoil than my std .30-06 with factory Federal 180 gr bullets. With scope dots it is dead on at 200, 280, 400, and 520. Plenty of energy all the way. The best I can shoot with it is ~1 1/2 @ 300 yards and about 7 inches @ 500. Lots of things change at 500.

As for the others, I don't know too much, but expect that .30-06 with 200 gr bullets would be serious. .375H&H AI is basically a .375 Weatherby with cheaper brass plus all of the Ackley Improvements. Read what Warren Page says about his use. Killed lots of elephants.

Let the flames begin...

Just to be clear on my posts--

No offense intended DSC and I appreciated your link--but when folks say stuff like "nearly impossible to hurt yourself" I get real nervous, as we are dealing mostly with males here and everything is possible.

FWIW, improving represents to me, a generally maximum gain of 50fps on the 06 case and a 100fps gain on the 7x57 case. (edit-over its parent loaded to the same approx pressure. Not enough time spent with the 257--maybe was lucky with the 7x57 and should have kept it...:))

That is it.

Each rifle is a law unto itself and can't be approached from some other gent's data. I had an AI job that netted nothing. That can happen.

Careful handloading keeps you from getting hurt, period.

The reduced trimming required on an Ackley Improved design may well exist but the reason for this is open to question. The accepted explanation has been that the sharper shoulder stops the migration of the brass under pressure. In an attempt to prove/ or disprove this, I decided to do a comparison between a standard 30/06 and a 30/06AI. So far, I have tested only the standard 30/06 to see just how bad the case strtching "problem" was. I took a piece of new Remington brass and loaded it with a stiff but acceptable load of 4350 (54 gr) and a 200 grain bullet. I neck sized only and loaded and fired the cartridge ten times. On the first firing, it lengthened .002" (from 2.484 to 2.486). It is worth noting that sizing of the neck lengthened the brass by .003" so after sizing, total growth was .005". The seond firing shortened the brass by .001" from the sized measurement for a net gain so far of .004" from new. Sizing this time lengthened the brass by .005". The third firng again shortened the brass by .001 from the sized length so we were now at 2.492. The pattern of lengthening from sizing and shortening when fired was to repeat itself from this point forward but the sizing produced somewhat less lengthening (usually .002")and case growth was minimal from this time forward. In fact, seven more firings resulted in a growth in length of only .004".
I suspect the initial case growth was related to rifle/cartridge fit as much as anything. The rifle (an old Model 54 Winchester)showed about .003" headspace on a "go" gauge and about .005" head clearance on the new Remington brass. This .005" would account for .005 " of the the intial stretching which took place over the first three firings. Subsequent change in length was, in my opinion an artifact of the sizing/stretching of the neck and most lengthening was in the neck.
When I fired it for the tenth time, I then took the case and ran it through an RCBS FL sizing die. This resulted in alengthening of a whopping .006". I have every reason to believe this would repeat. My conclusion, so far, is that the 30/06 doesn't stretch much from firing but does from sizing. A full length sizing die in a standard caliber reduces the brass to near factory dimensions. If the rifle chamber is generous (this one was)restoring the brass to factory diameter means that brass will be forced forward as it is sized down. The size difference between AI chambers and dies may be somewhat less which would mean less tendency to move the brass froward from sizing.
I'll get around to rechambering the M54 sometime soon and we'll see what the AI chamber does to case stretching. Frankly, I don't think it will do too much. I do think the full length sizing operation will lengthen the brass less but this is mostly because my FL sizing die is only .002" smaller in diameter than the rifle chamber at all points. We'll see. GD

Greydog,

Thank you for the work you have done to date on this question of case stretching and the supposed benefit of AI chambers.

I have had AI chambers and K chambers for decades and I see no significant difference in case stretching.

Looking forward to more from you on this topic.

Have you thought about growing a claro walnut tree, nurturing it, then cutting it down, and hand rasping it for a stock for your next rifle? Just a thought bud.... SIX months???

I don't know personally about any of the cartridges you mention as far as AI'ing goes.
I have two AI rifles now, a 223AI and the 250 Savage AI. That 250 Savage AI is about the best rifle I have. The 223AI is also excellent.
To the point; not all AI chamberings are created equal. I had a 35 Whelen AI and would never, ever do that again. The extra effort involved with that rifle produced about 25 FPS gain, not enough to have me to go thru the grief of having that rifle built again.
I can not conceive of AI'ing a 375, but that's just me.
I think the 30-06AI would be a great chambering, and the 7mm Mauser also. The rest of them are not of any interest to me. But, as always, YMMV

I only have one Ackley chamber,so i'm hardly an expert.It's in 22-250.I fireform with a max load in the standard case and loose about 200 fps.After fireforming, I gain about 200fps,which puts it at or near the 220 swift.The formed case hold exactly 1 grain more liquid than the swift.This seemed to be a worthwhile gain to me and worth the extra effort.As someone else already said,not all cartriges will gain much by being "improved".By the nature of the beast,it seems like the more taper the parent case has, the more gain you will see.I would suggest looking in a good loading book and compairing for your self.My thoughts are that a custom rifle gives you an excuse to do something unique,so I probabley would do a Ackley.Hope this mans opinion helps! Lightman