reloading 243 ackley improved

SussexFallow

Well-Known Member
Hi chaps

I need some advice as I am about to reload for ai rifle. As I understand I can fireform using some ammo I reloaded in 243 and then use the brass and new dies to reload for the ai cartridge. Would this be correct? Also what sort of bullet heads would you suggest for fox Roe and fallow .

Atb Steve
 
Mine is a 1 in 8 and I currently use 85grn Sierra BTHP Gameking, 46.5grns of H4350. Superbly accurate but off the top of my head I am not sure of the legalities in England??? Whether that works in your rifle or not...

I know that a 1 in 8 will certainly stabilise 100grn and 105grn, 1 in 10 may need a bit of trial and error to see what accuracy you are getting with the heavier bullets.

I sought advice on the powder when I started and although there are others H4350 certainly works for me.

I started off with a couple of boxes of Federal 80grn factory rounds and once fired loaded as you have described. After the first firing with the factory rounds the cases needed minimal trimming. The last couple of reloads have not needed trimmed at all as the AI case shape essentially prevents case stretching.
 
Hi chaps

I need some advice as I am about to reload for ai rifle. As I understand I can fireform using some ammo I reloaded in 243 and then use the brass and new dies to reload for the ai cartridge. Would this be correct? Also what sort of bullet heads would you suggest for fox Roe and fallow .

Atb Steve
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It's only correct if you are using new brass and loaded these yourself. Bullets for the 243 Winchester are the same as those you'd use for the AI. ~Muir
 
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It's only correct if you are using new brass and loaded these yourself. Bullets for the 243 Winchester are the same as those you'd use for the AI. ~Muir

Muir actually makes a good point. I often wonder about people asking for load data on here, 'as one man's meat...'

Hence when I responded I pointed out 'whether that works in your rifle or not...' and 'certainly works for me...'

All I would say about the .243AI is that you won't go far wrong by starting with a load at maximum factory recommendation for .243 and working up from there watching for pressure signs and accuracy tailing off.
 
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I am not one who automatically thinks that an Ackley chamber qualifies for maximum loads in the parent cartridge. I have in my possession, the last of a long string of Ackley guns I've owned, a 30-06 IMP, that maxes out at the same loads as the standard 30-06. I would be more cautious in my loading, starting with beginning loads for the 243 and working up from there... but that's me.~Muir
 
I am not one who automatically thinks that an Ackley chamber qualifies for maximum loads in the parent cartridge. I have in my possession, the last of a long string of Ackley guns I've owned, a 30-06 IMP, that maxes out at the same loads as the standard 30-06. I would be more cautious in my loading, starting with beginning loads for the 243 and working up from there... but that's me.~Muir

Safety first Muir, but why would you have an issue with starting at maximum recommended loads for the standard cartridge in an AI configuration? Otherwise there would be no advantage or point in the AI other than less trimming perhaps being needed. I accept that the shoulder angle will cause differences in powder burn etc and therefore pressure variations but it would be unlikely to show much of a benefit in MV using the same powder load.

This is the first AI rifle I have owned and interested to hear comment from those more experienced than me.
 
if you start at the beggining load for a standard .243 (say 10% below based on h2o capacity of 53gns youre at 47.77gn) that puts you well below the start capacity for the ackley case (10% below 58gn is 52.22 gns) which is also dangerous!

looks to me like starting at standard max capacity puts you in the region of 10% below ackley capacity.

but then what do i know - i just ram em to the top and plug my ears - probably lucky that blaser dont make AI versions:rolleyes:
 
Safety first Muir, but why would you have an issue with starting at maximum recommended loads for the standard cartridge in an AI configuration? Otherwise there would be no advantage or point in the AI other than less trimming perhaps being needed. I accept that the shoulder angle will cause differences in powder burn etc and therefore pressure variations but it would be unlikely to show much of a benefit in MV using the same powder load.

This is the first AI rifle I have owned and interested to hear comment from those more experienced than me.

I got news for you: There is very little to be gained with an Ackley chambering. The case capacity difference between a 243 and a 243 IMP is 6.3%. The rule I have gone by, and it's an old one, is that velocity increases at 1/4 the increase in case capacity. This means that you will utilize a 1.5% increase in muzzle velocity...when all other variables are the same. These being barrel length and type of powder and pressures.

Look at it this way. If you increase the usable case capacity by 6% and leave in the same amount of powder, you would expect (generally) lesser velocity, would you not? For a given bullet and powder it takes a certain amount of pressure to push a bullet out of a barrel at a given speed. By increasing the case capacity you have just lowered the pressure (say max @ 60K psi) and most likely, the velocity. So. What to do? You increase the powder until you reach the same velocity. You have achieved this velocity by generating the same pressures, with that same powder, as you had with the standard load. So now you have added more powder and gotten the same velocity and pressure. Now you add more powder because the Ackley Improved cartridges are stronger, right?? Wrong. You're done: 60K max pressure. Why would you get even that 1.5% increase in MV? I'm not sure but most likely it is due to the increase in powder weight. The added weight of the powder itself must be accounted for in internal ballistics and this weight will change the burning rate of many powders. (Check Lee's book on compressed loads) In any event, the velocity difference would be about what you would expect in standard deviation on a chronograph and most likely be within the accepted norm of pressure readings. If AI shooters measured pressures they would get a hairy surprise. Here it is the custom for gunsmiths to suggest ridiculously long barrels for their Ackley chamberings. One friend of mine had a 30 " barrel installed. His velocity increase is about what you'd expect for such a long barrel and he said his powder charges are about what he used in his standard 243. One fellow on this board boasted velocities of his 243AI and a 105 A-Max... at pretty much exactly what the standard 243 obtained.

The classic "pressure" signs aren't always evident in fired cases, even when high pressures are at hand. Ackley chambers are notorious for hiding pressure do to their straight walls (and subsequent adhesion to the chamber walls during peak pressure) resulting in lack of back thrust... and the practice of neck sizing only. This doesn't mean that pressures aren't high. You just aren't seeing them.

In the Lyman #43 manual (IIRC) there is an article by Ackley saying that high intensity cartridges weren't worth "Improving". A 60K cartridge must remain a 60K cartridge. Ackley told me that the reason for improving a cartridge back in the 50s and 60s was so that people could use the slow burning, cheap, surplus powders in cases that were otherwise unsuited for them; like the 30-30 Winchester. He admitted that his experiments Improving many different cartridges were done because he had the means and wherewithal to do it...and he loved ballistic experimentation. He also admitted that for much of his work he ran blind with no access to a pressure gun and just the use of a Tipco Time Meter chronograph.

I am not saying that the rifle and chambering is bad. Many of my Ackley IMPs were tacdk driving screamers and I took them on that account. You will enjoy your rifle but remember, there is no free lunch with ballistics, and starting out on Max is silly. My opinion, of course.~Muir
 
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Muir of course it right on pressures, Ackley to prove the point on how the Improved case reduced back thrust used an old Winchester lever gun and as I recall in one experiment ever removed the locking bolt just relying upon the levers linkage to hold the breech closed. The pressure was there but not transferred to the breech bolt and unless you understand this may end up in trouble due to excessive pressures.

In my case of the 280 AI my goal of reaching and equaling the velocity with a 140 grain 7mm bullet to that of the original 280 Ross loading is not going to be very difficult as according to the Hornady book the normal 280 Remington with the right powder can do so just. The bit of extra powder capacity should make it that bit easier :D.

Now in the 30-30 AI in a suitable rifle, i.e a good strong bolt action ;), I cannot see why it would not be possible to reach 3000 fps with a 125-130 grain bullet however the pressure would be way above the SAMMI norm and in line with cartridges such as the .243, .308 and 270 Winchester and not down in 30-30 levels. The case would not be a problem but firing such loads in a Winchester 96 or Marlin 336 would not be advisable. My current High Pressure loads for the 30-30 with the 130 Grn Hornady SP achieve just over 2800 fps and case life is good. In fact I have yet to scrap any cases through stress signs. With the extra powder space of the AI another 200 fps should be fairly easy to achieve.

Oh yes the data I am using was obtained in a pressure gun my Pedersens publishing for an article in Rifle shooter.
 
243 ai

Hi chaps

Thanks for the pointers. I have a batch of new lapua loaded with 70 nosler bt over h414 . Think off the top of my head about 2 grains under max. These were loaded for my 243. Im changing to ai as a nice custom rifle came up for the right money.

Atb Steve
 
Hi chaps

Thanks for the pointers. I have a batch of new lapua loaded with 70 nosler bt over h414 . Think off the top of my head about 2 grains under max. These were loaded for my 243. Im changing to ai as a nice custom rifle came up for the right money.

Atb Steve

Ahhh Steve another benefit of the AI is normally longer case life due to reduced case stretching.
 
I was tired when I wrote that, and sometimes I'm not as diplomatic as I'd like to be when I'm soggy and cold, but it's pretty much the truth... at least as I've seen it via pressure studies and chronographing. I have owned some fine rifles in Ackley chamberings but they are nothing magic. They live by the same laws of internal ballistics as any other cartridge. They are no stronger than the parent cartridge.

Now, in low-intensity cartridges fired in modern weapons, using suitable, modern, brass... such as I've outlined in my posts on the 6.5x55... that rule could be bent but not because of the Ackley chamber, but rather because the cartridge case wasn't being utilized to it's fullest at it's inception, with loading data adapted to inferior arms. As always, it's the loaders judgment.

I have recently come across an old article in Shooting Times (US) magazine that lists that 1:4 rule of pressures/velocity and a few other ballistic axioms. It's an interesting piece. I'll try to print the citation when I find it. Happy Shooting. ~Muir
 
.243 Ackley Loads

Hi Bordersman
This is some of my .243 Ackley Load Data Below for you to brows through it may give you some Ideas !

The Rifle is A Remington 700 Blue Printed action Bedded and Trued by Riflecraft Ltd, It has a H S Precision Tactical stock, Pacnor match grade Stainless heavy weight match barrel, Nightforce 5.5-22 X 56 NXS Scope, Extra high warne QR mounts,Warne 20 MOA bases, Versa Pod BipodThis Rifle shoots really well she loves 105Grn Hornady A Max Boat Tail Moly !


The Dies I am using are the Redding Competion Bushing Neck Die set, and a Stand Redding Full lenght Die set If I need to full lenght re size.The Re loading press I use is a Redding Turret Press, Combined with a Redding 2400 Match Precision Case Trimming Lath & a Redding Powder Measure & Redding Trickler. I have a CH case trimmer too and a Forsters Hand Neck turning tool, the Powder Measure that I use is a Hornady Bench Rest Grade powder measure with the dual micrometers.



Please Find My Hand loading Data/ Load Development/Chronograph data sheets !









This is my Hand loading load data, and load development sheets for you to see, remember these are a MAXIMUM for my RIFLE not yours as always start 10% less and work up carefully






This is information is intended just to give you some Ideas !




These are the other 2 TWO SHEETS ( EXBAL BALISTIC SHEETS )


Hope this has turned out OK.:oops:

PS I hope this has been of assistance to you.


Regards
Steve
 
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