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223 Ackley Improved

 
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  #8  
Old 09-24-2006, 09:05 AM
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Re: 223 Ackley Improved

The AI chambers are designed to me 0.004" shot in headspace compared to their parent rounds. This is by design.

Also by design is their ability to shoot factory loaded or standard loads in the parent case in the AI chamber and be totally safe. This is what the 0.004" crush fit offers as well as controling case stretching during fireforming.

If a rifle chambered for a 223 AI will not chamber a factory round, it is not set up properly.

That said, This is only for factory made ammo, not mil surplus which can differ slightly in some areas compared to the standard 223 Rem ammo.

Load and shoot, pretty easy. Generally rifles chambered for the AI rounds also shoot extremely well while fireforming so it can be used in the field.

One comment about AI rounds. I generally do not recommend them for HIGH volume rifles such as varmint rifles. Nothing wrong with using them but if you want 500 rounds of ammo, thats alot of fireforming just to get 500 cases ready to reload. Again, using standard loads work great so this is not a real problem but a consideration to look at.

One thing I have found with the 223 AIs I have built is that they can be a bit choppy as far as feeding goes. Typical short cased AI issue but they are choppier feeding then a standard 223 Rem for sure.

Kirby Allen(50)
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  #9  
Old 09-24-2006, 11:34 AM
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Re: 223 Ackley Improved

I haven't played with .223AI, but I play with .243AI a lot! What I've found is that if I chamber a factory round in my AI chamber, the round goes off just fine and the bullet goes where it's pointed. The problem is that my fireformed case has the beginning of case head separation. Sometimes is't just a flat spot in the taper of the brass near the case head, sometimes it's a recess. It's because of improper headspacing. If you've got a setup that will allow you to seat the bullet into the lands, you can do that and headspace off of the bullet instead of the shoulder and that will properly fireform you're brass. In my case, my bbl is a 1 in 14" twist. 100 gr. bullets can be seated to the lands, but they give 3" groups, so it's a waist of bullets, primers and powder to make cases.... Heck, they aren't fun to shoot either! 55 grain bullets won't come close to the lands, so that was out. What I have to do is neck the round up to .270 and then partial size the neck back down to .243. That gives me a bump in the shoulder that I can headspace off of. The result is that I get good groups because I'm using the right bullet weight for my bbl and I get properly fireformed brass because I have proper headspacing. Getting that first round loaded and ready to go is a pain though, because you have to size it down, check the fit, size it down, check the fit... until I find the right amount of neck sizing to just barely fit the chamber.
As I said, I haven't played with .223 AI, but having gone for the .243 AI, I've never regretted the chambering.
Coyoter
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  #10  
Old 09-24-2006, 05:08 PM
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Re: 223 Ackley Improved

Coyote,

Not trying to start a flame here but seating the bullets into the lands will not control headspace effectively. The reason is because it takes very little chamber pressure to start the bullet into the bore, even the primer blast with a high load density will get the bullet started into the rifling.

The bullet will be well into the lands by the time that the pressure in the chamber has gotten high enough to expand the case in any way so when your firing pin hits your primer, it will drive the round forward until the shoulder of the case stops against the chamber. The primer may well ignite while the case is moving forward but the case will not be stopped by the bullet hitting the lands.

When the powder begins to ignite the bullet will be driven into the lands and down the bore with only minumul chamber pressure. THen as pressure builds in the chamber to the point where the case will expand to fill the chamber the bullet is well down the bore and away from the case.

As the pressure continues to build to top pressures, the case head is then slammed back until it is stopped by the bolt face, you will still get case head stretching.

I also wonder if you are actually getting case head seperation or if you are seeing a pressure buldge on the case just ahead of the web.

Nominal case head diameter for the 308 and '06 class of rounds is 0.470". Unfortunately there is not a US brass maker that makes brass much larger then 0.465" in diameter. As such, unless your gunsmith designed the chamber properly you will get a pressure buldge on the case just ahead of the solid case web. This will generally be more apparent on one side of the case or the other.

This is not case head seperation in any way but instead, just the case expanding where it can to fill an oversized chamber.

If you are actually getting case head seperation, there is an easy fix in the 243 AI. Use 260 Rem cases, neck them down until they will JUST chamber with slight pressure on the bolt. THis works because there will be a secondary shoulder on the 260 Rem case when necked down to 243 and that will act as the control on headspace. This depends on how loose your neck is though. In some cases you will need to go up to the 7mm-08 brass and do the same thing necking it down.

Make sure that your case necks are not to thick though.

If you are actually getting some case head seperation on the fireforming loads, if you only partial FL size from there out you will still get good chambering ammo and you will also have very little case head stretching from that point on as long as you do not oversize.

Again, seating the bullets into the lands is a very inefficent way to try to stop case head stretching. Only means that the chamber was not cut to the correct depth for an AI chamber.

Kirby Allen(50)
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  #11  
Old 09-25-2006, 08:17 AM
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Re: 223 Ackley Improved

What is the best method to use for fireforming the 223 AI.

panhandlepr
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  #12  
Old 09-25-2006, 08:39 AM
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Re: 223 Ackley Improved

Load it with a mid to upper pressure load with a bullet of at least 50 grains. I like heavier bullets for fireforming. Just seems to get the case formed with less fuss. Any standard 223 Rem load will work well or factory load.

Kirby Allen(50)
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Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

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  #13  
Old 09-25-2006, 09:17 AM
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Re: 223 Ackley Improved

Hi Fiftydriver,
I can say for a fact that casehead separation is what I was getting. I drove 40 miles of two tracks to shoot gophers and the first shot had a case crack. This was only the second full AI load to be fired out of what were origionally Hornady VMax loads. I went home, pulled bullets (lots of them!) and broke out the RCBS casemaster. The dial mic. showed case head separation imminant in all but about 3 of the 60 rounds I had loaded.
Being new to fireforming, I got on the discussion board I was following at the time and was told about the "seat a bullet into the lands" trick. I used some Sierras that were 100gr and seated them .005" into the lands. I have to say, I did it and it worked as far as the actual fireforming went. As I posted earlier, I couldn't hit a pop can @ 100y and that was no fun. I got back on the board and did a little sniveling. That's when one of the posters told me about the false shoulder method. I've been using that method ever since and with great results.
The actual process is that I full lenght size virgin brass with a .243 die, trim to length and neckturn to .014, expand to .270 just running the expander ball through the case neck and then partial size back to .243 with a Redding bushing die. I then use 43.5gr of Varget and a 55gr Ballistic tip to fire form. The groups are double what I get with AI loads, but accurate enough to have fun and the brass fireforms perfectly. My attrition is almost exactly 1 split neck per 100 brass.
I suppose I should add here that I'm shooting this out of an Encore and you have to be a little careful with the case lenght or you can't get the gun to close. While seating bullets into the lands, I had a few that the gun wouldn't close on and when I tried to remove the round, the bullet stayed in the bore. I'm glad not to have that problem using the false shoulder method.
Coyoter
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  #14  
Old 09-27-2006, 01:57 PM
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Re: 223 Ackley Improved

I had a Rem 40X that wouldn't shoot consistently. I had it rechambered to 223AI and now it shoots the lights out. I loaded 27.3g 2230 and 52g smk in Lake City brass. It shoots .28 and I am very happy with it. I also got several hundred Norma milsurp 223 (1970's vintage) that fireform beautifully and shoot moa. I have noticed the choppy feeding but if I don't load the magazine full I don't seem to have much of a problem with that. Rabbits turn into a large furball floating in the air when I hit them, and prarrie dogs turn inside out. Great fun.
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