Ackley magic!

[Elwood]

A guy on another forum was advising about how a 22-250AI would fire a bullet at 5300fps. He used as his source a webpage that asserted a 22-250AI would do this velocity with a 36grain bullet. Holy Moses! 5300! I guess that this is about 1000 fps faster than the 220 Swift. I have been lead to believe that the 22-250AI is extremely close in capacity to a 220 Swift. Can you imagine where this increased velocity is coming from? The velocity fairy?
   Guys! please be carefull any idiot can post a load on the internet that is capable of killing you. Legitimate sources use pressure tested loads.
I read a article where Rick Jammison was pressure testing loads in 30-06 Springfield, 30-06Aclkey Improved, and 30 Gibbs. When loaded at safe pressure levels the Improved cases would add 100-150  feet per second over the 06. There were loads recomended by underinformed individuals that had extremely dangerous pressures and velocities that were better than safe loads.
  If something seems to good to be true it usually is.
Elwood

[Graybeard]

Any time you are told an AI round gains more than that rough figure of 100-150 fps over the parent case the extra over it is gained by adding pressure over and above what the parent case is loaded to. Not all AI versions will add even that 100-150 fps but none will add more without an increase in pressure.

While I like some AI rounds I think the world would be a better place if Ackley had been an auto mechanic rather than a gunsmith.

[mjbgalt]

agreed.


however the .22-243 will do all that and then some, depending on the twist.

been thinking on building one when i have some extra dough.

[nomosendero]

Elwood, if someone is stupid enough to believe that 22-250 story they are too stupid to load std. rounds also, to heck with the other so called forum if they are too stupid to delete it!

Magic, well of course not!

I do agree with Bill concerning 100-150fps gain, that is in std. '06 head cases & '06 taper, esp 06 length & 30 cal. & under. I expect a round like the 35 Whelen to be a little less than that, but in that round the sharper shoulder is an advantage for the reloader. I have an '06AI & the AI conversion alone maybe gave 100 fps with a long throat/seating to allow somewhat more. Many with the 280AI are getting around 150 more vel.

My 25-06AI gives a solid 125fps more. Was that worth doing, for me it is, with a 25-06 with warm but safe loads & a 26" tube like my Sendero you are looking at 3,400 with a 100 gr, with a 26" 257wea you are looking at 3,650 & with my AI I can get 3,520-3540 range & with a 120 you can get 3,150-3,200 with my AI 3,325 with ease & a Wea. 3,400 and change. Point is, it depends on your goals & my goal was to be within 125fps of a 26" Wea. & about where a Vanguard 24" would be & I did that, but I have read of a couple of fast Vanguard tubes. I would rather have the match grade chamber & superior brass than a 125fps gain with expensive & inferior brass, just not a worthwhile bal. edge.
   
However, there's no logical or ballistic reason that going the AI route will give the same gain in cases with more taper & therefore a higher percentage gain in powder capacity. It is interesting to read what Sierra bullets has to say about the 6mm RemAI, keep in mind that Sierra has one of the best ballistics labs going.
Quoting Sierra Man. #V
"In the example of the 6mm Rem., the excessive body taper & gentle shoulder design provides SUBSTANTIAL room for improvement. After fireforming, the improved case offers an increase of about 11 percent over the original design.. This is a fairly substantial difference & provides a significant boost in velocity over the std. 6mm Remington." Indeed, they show 3,200 with a 107 MK, pretty salty!

Cartridges of The World, 9th edition has this to say about the 30-30AI: "Many hunters have wished that the 30-30 had a little more oomph. The 30-30 Improved does just that by providing an additional 200 to 300 fps within the working pressure limits of the 94 Winchester action." BTW, they show 2617fps with the 150gr, I get 2,400fps with a 150BT in my Super 14, a good 250 over what the std round would do. Is that magic, well no, the std case has alot of taper as opposed to the AI with this cartridge. Again, more taper of the std. case, therefore more than the often quoted 100-125fps gain.

It is worth noting some data by one of the reamer companies of many AI rounds.
  http://www.4-dproducts.com/ackleychart.php

That being said, I don't think the AI's are for most people at all, but work for me fine in some cases.

[jeepmann1948]

I agree with nomosendero! I have several Ackley cartridges that show a definite improvement over their standard cousins.While not a true Ackley Improved,(but with the same 40 degree shoulder and min taper) The 22 CHeetah shoots a 60 gr sierra Hp @ 4060 with no pressure signs at all. As a matter of fact I can go faster but the accuracy drops off.(probably due to bullet design). My 6mm Ack is wicked with 70 gr Hps , the 257 Roberts is above 25-06 factory  ballistics,The 25-06 ack is working at real 257 Weatherby ballistics (tested with a chronograph with factory Weatherby Loads in a Mark 5). The 06 ack does much better than the factory 180 bullets but not much gain in the lighter ones ( just as P.O said in his book).The best thing I can say about The Ackley series is they are meant for the dedicated reloader that hates to trim brass all the time and takes the time to work up a safe load for their gun.
 Is the extra velocity worth it ? Yes if you can put it where it belongs! A Bad shot with an Ackley is just as bad as a standard factory chambering.

[Graybeard]

Aaargh, not again. Am I going to have to totally ban discussion of AI rounds on this site? Can folks not get it thru their head there is no magic to making a tiny increase in case capacity that allows it to perform like a far far larger case.

Damn it folks it's cuz you are running the pressure to unsafe levels and for no other reason you are getting the velocity.

No signs of pressure? Did the bullet exit the barrel? That's a real good sign you have pressure. There are no reliable indicators of pressure levels other than pressure testing equipment.

[nomosendero]

Aaargh, not again. Am I going to have to totally ban discussion of AI rounds on this site? Can folks not get it thru their head there is no magic to making a tiny increase in case capacity that allows it to perform like a far far larger case.

Damn it folks it's cuz you are running the pressure to unsafe levels and for no other reason you are getting the velocity.

No signs of pressure? Did the bullet exit the barrel? That's a real good sign you have pressure. There are no reliable indicators of pressure levels other than pressure testing equipment.

Bill, we can control the topic better I guess, I would prefer it doesn't come up at all. As you can see in my post I agreed with you with the '06 cases & gave detailed results with my 25-06 AI, which falls between the 25-06 & the Wea, which is only logical since the spread of the rounds is 250-300 fps & the AI is giving me 125fps & change in some cases. now I see that someone is saying the 25-06AI is matching the 257 Wea, which it will not without too much pressure. Yes the 257Rob. AI will meet some 25-06 fact speeds, but the 2 rounds loaded to the same pressure will put the 25-06 slightly ahead of the 257RobAI regardless.
I mentioned some rounds with considerable case taper getting more than the std. thought of 100fps gain because well, the cases are tapered more than the '06 case, thus more of an increase, nothing hard to figure out about that & I am sure that Sierra would gladly discuss why this gain occurred if some aren't sure why.

It is what it is & we don't need to make the AI rounds more than they are, which I have not done, but some seem to want to make an '06 a 300mag or a 25-06AI the same as a 257Wea & they are not.

Bill, you may want to comment further & being the owner you certainly can, but I had just as soon close this thread down.