Ackley Improved Chambers

Rifleshooter09 · Rookie Member Joined: Jan 29, 2006 Posts: 15

I have two rifles. one a .223 rem and a .243 Win that i would like to have rechambered to the A. I. version of each. Anyone know anything about it. the pros and cons. who does the work? Anyone with prior experience please let me know.

skip · Posted: Wed Mar 01, 2006 3:28 am Post subject: Re: Ackley Improved Chambers

I have some experience with Ackley Improved rifles and own one myself.
Do you understand the concept of an AI chamber? minimal taper, 40 degree shoulder?
There are basically only pro's that are achieved by an AI chambered rifle, case life is greatly improved, case stretch is also decreased dramatically.
Because of the new case dimensions the case will now hold more powder (depending on original case), which gives you a higher muzzle velocity.
A gunsmith that is qualified and has experience in Ackley Improving a chamber should be used.
As you would probably know factory ammo is fired through the improved chamber and comes out with the 40 degree shoulder and minimal taper.

I have probably missed something but im in a rush, cheers

yotebuster · Member Joined: Oct 16, 2005 Posts: 216 Location: Georgia

What area of the country do you live in Rifleshooter? Maybe someone can make a recommendation based on your location.
What make and model of guns are they? Very Happy

Yotebuster.

Rifleshooter09 · Rookie Member Joined: Jan 29, 2006 Posts: 15

I have done considerable study on the Improved concept and while i don't consider myself an expert i do know the basics. I have run into ppl who had trouble with fireforming brass properly etc etc. just wondered if anyone and any bad experiences or if things went exactly as planned. i have had retired machinist tell me that the minimal body taper is actually better for extraction than a more tapered case. Can't explain that one but thats what ackley says too. Thanks for the answer skip. What caliber is your rifle/weapon and how much velocity do you think you gain?

One rifle is a Savage 110 in .223 rem the other is a Stevens 200 in .243 Win. the .223 is a damned good shooter. 1/4 moa groups when it and i are both having good days. the .243 is still out to prove itself. still Doing a barrel break in on it.

I live in the Pacific Northwest yotebuster. I have heard of one gunsmith a lil jaunt from here that is supposed to be dang good but i haven't been able to get ahold of him. i know the .223 is a very popular improved chamber but i don't know about the .243 the hard part might be finding someone with the right reamer. I know you can buy em from midway but i don't reallly wanna buy a 100 dolllar reamer for cutting one chamber.

thanks for the replies guys any other information ya'll have would be appreciated.

watch yer topknot

skip · Posted: Sun Mar 05, 2006 4:39 am Post subject: Re: Ackley Improved Chambers

I have a Sako L691 (Heavy Barrel Varmint) in .25-06 AI, I think In my particular Cal I gain probably 300 fps.

They feed very well, I have had no problems in that department.

BillPa · Member Joined: Mar 17, 2005 Posts: 89

Rifleshooter09 wrote:

I have two rifles. one a .223 rem and a .243 Win that i would like to have rechambered to the A. I. version of each. Anyone know anything about it. the pros and cons. who does the work? Anyone with prior experience please let me know.

A "True" improved cartridge will safely fire the parent factory cartridge if chambered correctly. A factory round will headspace on the neck shoulder junction with a .004" crush fit. Problems usually come from either a barrel chambered wrong or over resized brass prior to forming.
For a existing chamber, the barrel must be set back and then rechamberd. Failing to do this results in a longer chamber creating something other than a true AI.
The second mistake is resizing brass using a AI die,pushing the junction back the .004".

Here are three examples, a 22-250AI,250-3000AI and a 270-308AI next to the parent cartridge.

Notice,in all three examples, the location of the neck-shoulder junction.

Here are the three parents,smoked to show where they headspace in the AI chamber.

Next,the parent, a chamber cast and a formed 250-3000AI.

Of course after forming,handloading is a must,but factory ammo can be used in a pinch,but with slightly reduced velocities. In the case of the 270-08AI being a true wildcat ( actually an "Improved" wildcat) , no factory ammo exists, handloading is required.

There is always a debate if there are any real advantages to an AI. Generally velocities are the reason for chamberng. The 250 pictured,using a 100 grain bullet, easily reaches 3200 fps without loading to the max. Other reasons are a more accutate method of headspacing and reduced case stretch, ie brass life.

The most popular are 223,22-250,257,280,30-06 and more recently gaining some interest,the 260. Those show the greatest velocity increase over the parent rounds while others only a modest gain.

My list of AIs currently include a 22-250,250-3000,270-08 and 280 with a 260 and '06 in the works.

If your thinking or plan to have an existing barrel rechambered,make sure the 'smith is going to set the barrel back. If he/she says its not needed,find someone esle to do the job.! If its a new barrel/chamber or and barrel chambered in a shorter round like a 250 Sav going to a 257AI,ask for the chamber specs. There isn't a SAAMI spec for improved chambers. Some order reamers to their specs and my have differences dimensions. My 250AI was cut with a reamer having a .283" neck. Not a problem except loaded round measures .284" which require turning for a .2815" diameter.

Well, hopefully this helps!

Bill

DallanC · Site Admin Joined: Jan 18, 2005 Posts: 3572 Location: Utah

Holy smokes BillPa, great info!

Why dont you copy that entire thing with picture and post it as an article submission for the Handloading Articles section? Thats good stuff to share!

-DallanC

BillPa · Member Joined: Mar 17, 2005 Posts: 89

DallanC wrote:

Holy smokes BillPa, great info!

Why dont you copy that entire thing with picture and post it as an article submission for the Handloading Articles section? Thats good stuff to share!

-DallanC

OK, I'll redo it a bit with somemore details,hopefully later today.

Bill

Handloader · Posted: Wed Apr 05, 2006 7:46 pm Post subject: Re: Ackley Improved Chambers

Darryl Holland lives in Oregon, your neck of the woods, Rifleshooter. He would be a good person to perform the correct gunsmithing and probably has reamers in house. I have a 223AI, 257AI and 7X57AI and am well pleased with the results.

The main disadvantage is the process of fireforming. I like to have around 250 loaded rounds for each rifle and fireforming the brass takes that extra step, however, I know other AI shooters that simply take their initial rounds to the field and use them normally.

All of mine have shown significant velocity increases but one of the main reasons I like them is because they simply look great!

Over the years, the advantage of the 45 degree shoulder has been the subject of much discussion and debate. The RCBS improved versions feature less of an angle. While it may be academic, the 38 degree shoulder has theoretical advantages as far as gas flow turbulance from the case to the neck, but, the debate continues. Father Ackley's design if fine with me.

Flint54 · Posted: Thu Apr 06, 2006 5:45 am Post subject: Re: Ackley Improved Chambers

For informational purposes I truely believe that the "BEST" Person to contact about Ackley Improved Cartridges is a man named "Mike Bellm". Mike was an apprentice of P.O. Ackley and lives in Oregon, Bend I think. Here is a link to his site and contact information, also an article he wrote on some of P.O. Ackley's observations and ideas.

One thing that I would like to add is that if you are converting to an Ackley chamber is that to achieve optimum accuracy you need to cut off enough of the chamber area so as to remove all of the neck area from the original chamber. Doing this will allow who ever rechambers the barrel to align the chamber true with the bore. Also when fireforming it is advisable to use a low end charge and seat the bullet so it is in contact with the rifling, this will insure that the case does not move forward upon firing. This is just a bit of insurance that works very well for me. Cool

www.bellmtcs.com/TOC.htm

www.rvbprecision.com/m...lm.php?b=5

Handloader · Posted: Thu Apr 06, 2006 9:06 pm Post subject: Re: Ackley Improved Chambers

Flint54: thanks for the link! One of the allures of going Ackley Improved is that the handloader is entering into unchartered waters, at least for him. Ackleys loading manuals give some starting points, but, the finer points of Ackleyizing are often overlooked, such as you have mentioned.

Steve Timm has done much to popularize the 223 Improved and while not an official Ackley version (I don't think he did one), it follows the same formula.

Now, Flint54, what Ackleys do you load for?

PaulS · Posted: Fri Apr 07, 2006 4:20 pm Post subject: Re: Ackley Improved Chambers

I don't like to speak ill of anyone but I have seen some of what Mike does. One was a 45-70 contender that ended up in three pieces with a half box of factory ammo. Some of the loads he recommends are higher pressure than SAAMI proof loads - Like recommending .003" expansion at the web in order to find maximum when it has been shown that .0005" expansion at the web can indicate pressures as high as 70000 psi depending on brass and chamber? Recommending loads that cause 6 times that deformation is reckless if not bordering on criminal.
Take a long look at the guys website and what he recommends and does before you decide he is Ackley Jr. ok?

The forgoing note is the opinion of one man - it has no bearing on the opinion of anyone else and does not in any way represent the opinion of the management or ownership of this board.
copryright(c)2006 by Paul Stephens

Flint54 · Posted: Fri Apr 07, 2006 8:28 pm Post subject: Re: Ackley Improved Chambers

My only Ackley Improved is an old Custom Remington .250 Savage Ackley Improved. It shoots very close to .257 Roberts with very good accuracy.

As far as Mike goes, in every one of my dealings with him and also Gary Reeder these two individuals are some of the most informed, intelligent and safety oriented people that I have delt with as far as TC Contenders. I have a .308 Bellm and a 7MM Bellm that are the two most accurate Contenders I have ever shot. I thought about the .309 JDJ but in looking at the loads used to achieve the velocities claimed they are too close to the boarderline for my tastes. I can't speak for the 45-70 as I have no knowledge but having the same caliber myself it can only be safely loaded to a MAX of 28,000. Loads developed for the Marlin CANNOT SAFELY BE USED IN A CONTENDER. I observed an individual use some GARRET loads and he also had a 3 piece barrel, the lug came off the barrel and the muzzle tamer came off also, the frame was ruined and stretched. If you want heavy 45-70 loads in your pistol get an ENCORE!

I used Don Scherer's case head expansion method for loading my Bellm cartridges with excellent results, you have to use NEW CASES ONLY! Once I observed .00015 expansion I dropped a minimum of 1gr. for a MAX Load. These loads show no case head expansion in my firearm. I really believe that the .003 figure was a complete misprint I surely would have questioned that prior to loading as should any informed reloader. I would hope that anyone getting to the level of using case head expansion would have been in the reloading arena for quite a few years and not a first time individual.

Anyway I do not intend to create an agguement over Mike, If you have any questions please PM me Thanks, Bob K. Cool

Handloader · Posted: Fri Apr 07, 2006 10:50 pm Post subject: Re: Ackley Improved Chambers

duplicate post, big fingers, sorry

Handloader · Posted: Fri Apr 07, 2006 11:00 pm Post subject: Re: Ackley Improved Chambers

PaulS: your words of wisdom are important warnings to all that would undertake Improved or wildcat cartridges and you point out an obvious problem, that of taking loading data literally for a single source. Like Flint54 suggests, the .003 is, hopefully, a misprint and would lead the novice down a very rocky and dangerous road. I've noted this problem to Bellm so that he can correct the error. If his intent was .0003 headcase expansion, that would with range of normal pressures in strong actions.

As we expand our knowledge of cartridges and working pressures, of SAAMI and a host of other aspects of handloading, we become more aware of the associated risks. Sorting out which risks are acceptable and which are not can give improved results on the one hand or can lead to serious injury on the other hand. Some formal data pressures are held low due to weak actions still in use -- the 45-70 and 45 Colt come immediately to mind. Some data, however, is developed with the highest allowable pressure possible -- the Weatherby cartridges for example -- and even approaching those maximum levels must be done with utmost caution*.

Ackley designs were not, IMO, intended to exceed the factory pressurs of the round it modified (some exceptions include the 250 Savage and 257 Roberts, both held to lower than safe pressures in strong bolt actions because of weaker lever action and pump action rifles). Increased velocity is a matter of increased capacity. The other attendant advantages of case stretching are part of the advantages as well. The 250AI and 257AI show remarkable improvements over factory ammo when chambered in good bolt action rifles, improvements disproportionate to the mere increase in case capacity.

All of which is to say that such manipulations of loading data should be well researched and cross checked.

*My son and I are going to realize a lifelong ambition of hunting Africa next year. We contacted several outfitters at SHOT in Las Vegas and were surprised to hear that the Weatherby is not held in high esteem for African hunting! The main reason seems to be related to the higher pressures of the Weatherby ammo sometimes doing poorly in the heat associated with African hunting. Lower pressure big bores, such as the 416 Rigby, seldom experiece extraction problems. Or, so they said. If anyone following this list has personal experiences/knowledge I would appreciate a PM or starting anothe thread on the subject. My Rigby is on its way!!