223 Ackley Imp.

H

Harpy

New member
Here are some points about the 223 Ackley Improved, et al.....
1. The neck die will work until your cartridges start to chamber hard. The action/bolt will be tough to get closed and you must then run the cases through a F.L. sizer to reset the shoulder length. Personally I like Reddings and seat with a Wilson "Straight line".
2. The case length is the same and so is the trimmer but the point at which headspace is measured is different. Instead of a .330 Datum line on the shoulder the Ackley measures from the junction of the neck and shoulder. This is why you cannot "bump" the shoulders back with a neck or standard die. You must have the Improved version of the dies to avoid adding dangerous headspace. RCBS cartridge mics wont work to set sizer dies and this is a disadvantage. It is hard to check your headspace at the cartridge without special tooling.
3. The design of the improved cases causes them to not need much trimming at all. The 40 degree shoulder all but completely stops the forward flow of brass that results from firing the cases. This also helps the brass last a very long time but you still must anneal the necks as required.
4. With respects to recoil, another design plus is the cases straight sides which redirect alot of the rearward bolt thrust onto the sides of the chamber. Long tapered cases like the 300 H and H recoil heavily because of the resulting bolt thrust. Parker Ackley took the locking block out of a Model 94 Winchester and safely fired it with 30-30 A.I. ammo {after rechambering it to that caliber} with nothing but the finger lever holding the bolt closed. To answer your question about a muzzle brake... I wouldn't worry with it. The caliber dont recoil much anyway and the increase in pressure you can attain with the improved chamber is negated somewhat by the straight sides. Which brings us to another point...
5. The increase in velocity you can now enjoy has a cost. You "gotta pay the piper" if you are going for the most possible velocity. My experience and borescope prove that the extra velocity is not worth the increase in throat erosion. {the conversion doesn't make it a complete barrel burner but it does speed up the process} The 223 was carefully designed for the Army to NOT be a barrel burner but still have high velocity. I believe this is one of its best attributes, its nice to know that the expensive barrel I just put on will still be shooting great long after the 22-250's and 220 Swifts are burned out.
6. I have barreled and or chambered many improved caliber rifles and presently own three. It has been my experience that most guys, myself included, do not load their improved rifles as hot as possible. But rather stick to factory loads and enjoy the lower recoil and lack of trimming. With that I have to admit that improved calibers are hardly worth the cost and some show no improvement at all{like the 270.} It is much more recommended to "improve" a gun like the 30-30 in which you can safely get near 308 ballistics with a lever gun. One more thing, the improved cartridge design requires a chamfer around the breech that is wider{heavier} than factory guns. Without this it could fail to feed because of the sharp 40 degree shoulder catching the breech. The fella that has a rifle jamming mentioned above should have taken it back or to another smith when the problem first surfaced. None of my conversions have ever failed to feed properly. Of course it goes without saying that the rifle converted will still shoot factory ammo just fine and the conversion doesn't alter accuracy. Good luck.
 
This was supposed to go with "223 AI questions" a few post back....dont know how I did this, Maybe the moderator can add it to that one.
 
Thanks for the great info on this caliber. As you probably saw from my posts a few days ago, Darrell Holland built me a custom Remington 700 in this caliber and I recieved it last week. I have only ran about 60 rounds through it for break-in and fireforming, and have not had any feeding problems. I fireformed my first 50 cases, but I may try the cream of wheat/Bullseye method on a few cases to see if it blows the shoulders out properly.

As I expected, my cases were shorter after fireforming, and they did not all shrink the exact same amount.

I plan to head to the range tomorrow and fire AI loads for the first time. Fireform and barrel break-in loads shot a consistant .75. I am hoping for a little better from the AI cases tomorrow.
 
Harpy,
I can move a topic to another forum but can't make it part of another topic. No big deal as this is fine as a new topic.

Good description of the AI family, however I have to disagree with one point. Recoil. Your description of the difference in bolt thrust is accurate and true, but bolt thrust has nothing to do with recoil. It makes no difference if the chamber walls or the bolt take all the thrust. It is all contained by the receiver. It is only the weight and speed of the bullet and powder expelled from the muzzle that determines recoil. Felt recoil depends on a lot of things like stock shape, action type, etc.

The headspace measurements for the AI chambers are hard to explain unless everybody is looking at the chamber prints. The important thing is that a factory parent round should be a slight crush fit in the AI chamber so there is no brass stretching. Due to loose SAAMI tolerences, it may not be a slight crush fit but will have less stretch than in a factory chamber.

Jack
 
Harpy,
On your point 6, you said,
"With that I have to admit that improved calibers are hardly worth the cost......"

If you are having a rifle re-barrelled, there should really be no extra cost to have your rifle re-barrelled in .223AI, as long as your gunsmith has the correct reamer. About the only "cost" would be lost time in fireforming, but the .223AI is plenty accurate in the fireforming process so I plan to hunt with it during fireforming.

Due to the detail gunsmithing work you describe above, it is not a given that any old gunsmith with the correct .223AI reamer will build a well functioning rifle in .223AI.

I also believe you should start the fireforming with virgin cases an not ones that have already been fired a few times and had their necks and shoulders already stretched. This may add some extra cost if you planned to use previously fired cases.

As you pointed out in your overview, any "cost" may be negated by the extra times you can use AI cases, and possibly less wear and tear on your action and bolt, providing you do not load too hot.
 
I understand what you are getting at in regards to "felt" recoil, however....... "bolt thrust" is a rearward force. This rearward force is not stopped, negated or absorbed by the receiver. No matter what creates it{ heavy bullets, heavy powder charges, etc.}, it does not dissolve but is merely passed on to your shoulder. It is also felt as a greater force in recoil as the headspace goes up, to the point that the receiver is wrecked. What you are alleging implys that we could take a given load, add dangerous levels of headspace and not feel any difference in recoil or increase the rearward pressure on the bolt but not feel that same increase at the shoulder????? I cant imagine wrecking an action like some of the pictures I have seen with excessive headspace but not adding recoil too. There are all kinds of different factors that cause recoil to be felt as greater or less. My favorite example is the difference between firing the bottom barrel of an over and under and firing the same load out of an old side by side with 3 1/2" of stock drop. Bottom line is that the same rearward thrust energy measured at the bolt face will be the same measured at the buttplate{unless its a recoil pad.}
With respects to added cost...you must look at all of it or risk fooling yourself. With an improved chambering I agree it should result in no greater cost from the smith{but it usually does}. The added cost are...new brass as you suggested for fireforming, a very good point. New and always expensive improved dies, a custom made cartridge headspace gauge, and increased barrel wear. Depending on the caliber you are trying to improve all this cost could gain you anywhere from nothing to about maybe 500 FPS???, and either the same or less accuracy. In the case of the 223, brass is neither expensive nor rare so you haven't negated any cost there. If your happy with it then Ok, that is the bottom line. To me the Ackley improved calibers have been something rather expensive but enjoyable to play with. I like them because they are different and will keep on playing with them. But I am different than the average bear as I also am a 'smith. Good luck.
 
I gotta disagree with you Harpy.

The total recoil is dependent only on the weight of the bullet and powder and their speed. How that recoil is absorbed in the receiver and ultimately transmitted to the buttplate makes no difference. You can look at the extremes:
If all the recoil is absorbed in the chamber walls or if it is all absorbed by the bolt face, it is the same amount of recoil transmitted to the buttplate.

Equal and opposite reactions. There is a given mass and velocity going out the barrel generating a certain energy against the rifle. No matter how that energy is applied to the rifle, it is the same amount of energy at the buttplate. There is no way to increase the energy inside the rifle.

Jack
 
Harpy:

I have to agree with Jack on the recoil issue. Absolute recoil and bolt thrust are two totally different forces which are accounted for in a properly engineered rifle action design.

Absolute recoil or recoil energy is the amount of force directed rearward as the cartridge “ejecta” is going out the end of the barrel. Ejecta is traditionally defined as the weight of the bullet plus 1.5 times the weight of the powder charge.

You can calculate the recoil energy of any rifle if you know the weight of the rifle, the muzzle velocity of the cartridge and the weight of the ejecta. This recoil energy is generally stated in foot pounds of energy and can be determined for each individual rifle, cartridge, and load.

In a rifle action, if everything goes as planned when the trigger is pulled, the recoil energy is transferred to the recoil lug on the rifle action which transfers the recoil energy to the rifle stock. It is an absolute value which can be mathematically calculated in each instance.

You and I both might perceive felt recoil differently from the same amount of recoil energy, - ie., I flinch and you don’t. In addition, as was stated, stock design, etc., may affect the amount of felt recoil each of us would “feel” from the same cartridge from two different rifles.

Bolt thrust is the amount of pressure in pounds/square inch which is exerted on the action locking lugs and the face of the bolt. The amount of bolt thrust can also be mathematically calculated, and is considered in the design of the action. However other things such as chamber wall smoothness, oil on the chamber walls, and other factors, can affect the amount of bolt thrust. When a rifle action is designed, the amount of bolt lug surface area to prevent “catastrophic failure” is calculated using a worst case scenario and is part of what is considered in the overall action design.

In a properly designed rifle action, bolt thrust is absorbed and contained within the rifle action and the chamber of the rifle. It is proportional to the amount of pressure contained within the cartridge case walls and case head size of the cartridge. Since the pressure is contained within the cartridge and is exerted in all directions within the case, nothing extra happens when you pull the trigger other than what you expect to happen. A 22-250 loaded to X psi internal pressure exerts approximately the same bolt thrust pressure on the bolt face and lugs as a 30-06 loaded to the same internal pressure if chamber walls are of equal smoothness, etc. They will have approximately the same bolt thrust pressure since both have the same case head size, but the difference in the amount of ejecta going out the barrel determines the different recoil energy of each cartridge.

When you introduce excessive head space as you describe in your example illustrating recoil, then you start testing other forces in the rifle and action – the strength of the cartridge case, the shear strength of the bolt lugs, and the ability of the action design to handle uncontained pressure. I have no doubt in my mind when a cartridge case expands in an uncontrolled situation that it will result in additional rearward thrust on the action as the cartridge case fails. However, I would be much more concerned with extremely hot gases escaping under thousands of pounds of pressure, flying schrapnel created by the uncontained forces within the chamber and cartridge exceeding the sheer strength of the bolt lugs and exceeding the ability of the action to handle the uncontrolled pressure.

Excess headspace, in an exaggerated example, would drive the cartridge case head back against the bolt head in much the same way that the gas rod in an FN FAL drives the bolt rearward on firing. If this were to happen, it probably would generate extra recoil one time as the action fails. How the FAL action absorbs this force is a totally different principle and discussion.

In summary, recoil is an illustration of Newton’s 3rd Law of equal and opposite forces, and bolt thrust is a measure of internal contained pressure within the rifle action. Bolt thrust pressure, under normal circumstances when you pull the trigger, does not translate into recoil if all goes as planned since that internal contained pressure is exerted in all directions within the cartridge case and seals it against the chamber wall and the bolt face. Only the pressure which is exerted on the internal case head is transferred to the bolt face and lugs, and the bolt lugs only "feel" a residual pressure roughly proportional to the difference in size of the case head and the surface area of the bolt lugs and the strength of the metal used in the bolt face and lugs. If the bolt lugs fail, only then you will have real "in your face recoil energy" directly proportional to the speed of the bolt times the mass of the bolt traveling backwards. OUCH!!! - BCB /ubbthreads/images/graemlins/smile.gif
 
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