Longcruise
New member
Jamison rechambered an '06 to '06 AI and shot the same cases, bullets, and primers at nearly the identical pressures as in the '06 and came up with an average of about 66fps "improvement" Just can't see it!
Ackley improved
- Thread starter White Eagle
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Bayou City Boy
New member
Longcruise:
As I had stated earlier, PO Ackley didn't even see a real advantage in any of his conversions if you were just looking for inceased velocity. And increaseed velocity was not why he played with straight walled cases with 40 degree shoulders anyway.
To each his own - some may like them, others may not, but I doubt that whatever side of the fence you're on that there's a clear cut right or wrong to the isssue.
Like I also earlier stated, I have a 257 AI simply because I like the looks of the cartridge case. For me, that was enough of a reason, and it didn't cost any more to have the barrel chambered in 257AI than it would have cost to have it chambered in 257 Robts at the time.
-BCB
As I had stated earlier, PO Ackley didn't even see a real advantage in any of his conversions if you were just looking for inceased velocity. And increaseed velocity was not why he played with straight walled cases with 40 degree shoulders anyway.
To each his own - some may like them, others may not, but I doubt that whatever side of the fence you're on that there's a clear cut right or wrong to the isssue.
Like I also earlier stated, I have a 257 AI simply because I like the looks of the cartridge case. For me, that was enough of a reason, and it didn't cost any more to have the barrel chambered in 257AI than it would have cost to have it chambered in 257 Robts at the time.
-BCB
James Lindley
New member
Longcruise.. It sounds to me like Jamison set up parameters and didn't take the cartridge all the way out and back like it was capable of..
To stop at the "near identical pressures of the original O6" sold the ai case short, as the ai's design would allow for higher pressures to be obtained before reaching dangerous pressure signs with said gun..
Higher pressure usually means more velocity to a certain extent...James L.
To stop at the "near identical pressures of the original O6" sold the ai case short, as the ai's design would allow for higher pressures to be obtained before reaching dangerous pressure signs with said gun..
Higher pressure usually means more velocity to a certain extent...James L.
I was criticized for posting something written in a manual about cartridge design. Let see if this gets past him. In Ackley Volume 1 they talk about headspace of the improved case .004 shorter than the parent case. Body taper no more than .0075 per inch for the improved.
I've got 8 Ackely rifles now and looking at a 9th maybe in a 30-06AI. Well good luck.
I've got 8 Ackely rifles now and looking at a 9th maybe in a 30-06AI. Well good luck.
Bayou City Boy
New member
Hi, roper:
Who's "him"? Me? I'm not looking for an issue to argue about.....with anyone. I hope you're not either....
I see your 0.004" dimension and have no diagreement what-so-ever with it. It's what Ackley mentioned in his handbok, and that's maybe the most often used. However, some smiths have used reamers that only use @0.002", so maybe anything greater than 0.000" will work? How about 0.003"? My 257AI happens to be @0.002" less and it works fine, and as a result, I used that dimension in my example. I've never lost even one case when fireforming.
The main issue is not having the same or more head space and expect factory cartridge cases to last very long when "Ackleyed". And just like any other head space issue to be safe, the Ackley concept probably has a safe parameter of +/- to work from. Please feel free to correct me if I'm wrong.
Incidently, did you ever check over at Saubier.com about the other issue we were taking about?
Hope you have a good day. - BCB
Who's "him"? Me? I'm not looking for an issue to argue about.....with anyone. I hope you're not either....
I see your 0.004" dimension and have no diagreement what-so-ever with it. It's what Ackley mentioned in his handbok, and that's maybe the most often used. However, some smiths have used reamers that only use @0.002", so maybe anything greater than 0.000" will work? How about 0.003"? My 257AI happens to be @0.002" less and it works fine, and as a result, I used that dimension in my example. I've never lost even one case when fireforming.
The main issue is not having the same or more head space and expect factory cartridge cases to last very long when "Ackleyed". And just like any other head space issue to be safe, the Ackley concept probably has a safe parameter of +/- to work from. Please feel free to correct me if I'm wrong.
Incidently, did you ever check over at Saubier.com about the other issue we were taking about?
Hope you have a good day. - BCB
Longcruise
New member
Didn't mean to ruffle feathers over personal preference. I don't own an AI and probably won't. That's just my preference. Hopefully my preference is as valid as anyone elses!!;-)
James, I don't get what you are saying as far as not going to the pressures it's capable of? Does converting to an AI somehow allow shooting at higher pressures than the '06?
Here's what he did. He took a win 30/06 rifle and test fired it with various factory ammo loads and read the pressures with an Oehler system. Then he loaded with various powders and bullet weights to the same pressures and recorded velocity, etc. Then, leaving the pressure measureing device attached to the rifle, hje rechambered it it '06AI and then loaded the same components in the same cases to the same pressures. Results were as I stated earlier, an overall improvement in velocity of 66 fps.
I suppose you could load your AI to pressures it's not meant to take and get higher velocity but unless the AI has a max pressure advantage then it wouldn't seem like such a good plan.
After the AI test he took the chamber to a .30 gibbs and did the same test getting an average of 104 fps improvement over the '06.
I surely was not knocking anybody for playing around with the AI chamberings for whatever reason they might have, but I think that with some exceptions (as stated above) most shooters go to the AI for more "performance" or velocity. From what I see it's just not there.
James, I don't get what you are saying as far as not going to the pressures it's capable of? Does converting to an AI somehow allow shooting at higher pressures than the '06?
Here's what he did. He took a win 30/06 rifle and test fired it with various factory ammo loads and read the pressures with an Oehler system. Then he loaded with various powders and bullet weights to the same pressures and recorded velocity, etc. Then, leaving the pressure measureing device attached to the rifle, hje rechambered it it '06AI and then loaded the same components in the same cases to the same pressures. Results were as I stated earlier, an overall improvement in velocity of 66 fps.
I suppose you could load your AI to pressures it's not meant to take and get higher velocity but unless the AI has a max pressure advantage then it wouldn't seem like such a good plan.
After the AI test he took the chamber to a .30 gibbs and did the same test getting an average of 104 fps improvement over the '06.
I surely was not knocking anybody for playing around with the AI chamberings for whatever reason they might have, but I think that with some exceptions (as stated above) most shooters go to the AI for more "performance" or velocity. From what I see it's just not there.
I use a mid-range charge of fast powder for the parent caliber, jamm my pill by say .005-.010" into the lands, and light it up. The amount that you THINK you are jamming by will only serve to compress the ejector spring and put the case closer to the boltface. My cases have a PERFECT shoulder and body on the first firing this way.
The ackely improved argument will go on for years, but I can say that my ackelys exceed their parent in the MV dept. Some better than others however. The main benefit from the AI conversions are first and foremost, the 40* shoulder greatly reduces case stretch, secondly, the 40* shoulder directs the plasma more into the centerline of the bore and keeps more of it directly off the throat, which when running similar pressures will yield greater throat life, and third is increased powder capacity.
If you shoot a 6.5x284 or any of the new short mags, you have benefitted from Parker's work, whether you realize it or not. Note the case taper and shoulder angles on these chamberings.
The ackely improved argument will go on for years, but I can say that my ackelys exceed their parent in the MV dept. Some better than others however. The main benefit from the AI conversions are first and foremost, the 40* shoulder greatly reduces case stretch, secondly, the 40* shoulder directs the plasma more into the centerline of the bore and keeps more of it directly off the throat, which when running similar pressures will yield greater throat life, and third is increased powder capacity.
If you shoot a 6.5x284 or any of the new short mags, you have benefitted from Parker's work, whether you realize it or not. Note the case taper and shoulder angles on these chamberings.
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chuckaholic
New member
Very few Ackley's gain more than a 100 fps loaded to the same pressure. As far as being able to handle more pressure this is only true where the parent cartridge is underloaded such as the 257 Roberts. In these cases the parent cartridge can be load up to higher specs as well still leaving the Ackley with a maybe 100 fps advantage. John Barsness has worked out that there is a 4 to 1 velocity ratio (potential velocity increases or decreases at about 1/4 the rate of case capacity) regardless of case shape given same pressures. VERY few Ackley's gain a 10% capacity increase which would mean a 75 fps increase for a 3000 fps load. The 150+ velocity increases you hear about come from simply loading to higher pressures than the parent cartridge. Just like magic handloads that beat the books.
the arguments will continue,..but the world record in BR (IBS) was set a few years back by an AI caliber. Rich DiSimone won with a 6.5x284AI and a 147gr clinch river. Anyone wish to argue against the world record???
if you want to talk similar pressures, then test 2 of the same caliber against each other. The ackely holds a lot more pressure while maintaining the primer pocket. I have run them to rediculous pressures and they held up. Their parents exhibited sticky bolt lift and loose pockets.
I will stand by my rifles who have never given me any issue. If there are NO pressure signs, then the caliber that runs 150fps faster is the winner. I have run them to 250fps faster with no sticky bolt lift or cratered primers. That is real world data from real world, factory actions.
I have heard everything about ackleys,..but few naysayers have spent the money to talk from experience. I have 3 as of now,..and several more on the design table. Long live Parker Ackleys work,....the man was ahead of his time.
if you want to talk similar pressures, then test 2 of the same caliber against each other. The ackely holds a lot more pressure while maintaining the primer pocket. I have run them to rediculous pressures and they held up. Their parents exhibited sticky bolt lift and loose pockets.
I will stand by my rifles who have never given me any issue. If there are NO pressure signs, then the caliber that runs 150fps faster is the winner. I have run them to 250fps faster with no sticky bolt lift or cratered primers. That is real world data from real world, factory actions.
I have heard everything about ackleys,..but few naysayers have spent the money to talk from experience. I have 3 as of now,..and several more on the design table. Long live Parker Ackleys work,....the man was ahead of his time.
chuckaholic
New member
What does a world record prove other than Ackley's are capable of fine accuracy?
Sticky bolt lift and loosened primer pockets are two different things. While AI'ing may reduce bolt thrust,likely, loosened primer pockets are related to the strength of the cartridges parent brass and will happen at the same pressure in a AI or non AI cartridge parent brass. And I have loosened primer pockets in one firing in a AI well before getting to the +250 mark while not in another non AI round of stronger brass.
The traditional pressure signs of bolt lift, reading primers, case expansion, have been shown to be a bunch of hooey by modern pressure testing equipment until way over kosher pressures, another thing Ackley was ahead of.
While AI'ing certainly helps reduce case stretch so does good loading practices like neck sizing, mininum full length resizing, and sane pressures.
Sticky bolt lift and loosened primer pockets are two different things. While AI'ing may reduce bolt thrust,likely, loosened primer pockets are related to the strength of the cartridges parent brass and will happen at the same pressure in a AI or non AI cartridge parent brass. And I have loosened primer pockets in one firing in a AI well before getting to the +250 mark while not in another non AI round of stronger brass.
The traditional pressure signs of bolt lift, reading primers, case expansion, have been shown to be a bunch of hooey by modern pressure testing equipment until way over kosher pressures, another thing Ackley was ahead of.
While AI'ing certainly helps reduce case stretch so does good loading practices like neck sizing, mininum full length resizing, and sane pressures.
hogwire
New member
I agree that when you change a cartridge's design you change the parameters for pressure, I think, Ha! My statement/question is: How do you decide what the limit is? All modern pressure equipment tells you is what the pressure is. How much is too much, I mean what determines a certain cases limit if you don't take case head diameters, primer pocket conditions, or bolt lift into consideration? Look at the SAAMI listed maximum pressures for each cartridge. There is a very wide variance, how do they come up with their recommendations?
first it proves the bunch who are the ones that are known for running loads into the unknown are still using the case design. One reason may be inherent accuracy, which I will also yield to the AI vs it's parent, but second is that I beleive the changed parameters of the new case design allow it to hold higher pressures or at least to have them present themselves in other ways. Wether that means it is right or wrong, it is the data I see. The cases seem to exhibit less pressure signs, but still when run too high, will not only maintain their primer pockets longer, but also seem to displace some pressure in other areas than the locking lugs and their seats. That to me, with lug seats and surfaces making 100% contact, and quite often in stainless actions, is worth everything right there. Gauling is now less of a concern on the load horizon in an action that even if a factory one to start, has now come close to the price of a custom by the time the smith finishes with it. Not only do I save brass life at higher pressures, but I save machine shop bills at the same time for anything from lug set-back to throat life. Those I'll take any day of the week, as do quite a few BR shooters, hence the "improved" design being so prevalent with respect to all other versions of case changes.
as far as 250+ fps increase, I got it in a match chamber in a 1:8 twist PacNor, so my internal tolerances were tighter than a rechambered factory bore. That may be the reason for increased velocity over others data. I was also running a bullet of ~.625BC which means a long bearing surface and more of a seal creating a higher and faster pressure curve also adding to the velocity increase. However, when you can get to 3208fps with a 140gr a-max in a 6.5-06AI out of only a 26" tube, you are wayyyyyyyyy overpressure. That is NOT arguable,..and when I saw the chrono reading from the first string, the remainder were taken home for de-construction. The cases exhibited not the slightest increase in bolt lift in a sako action that was making great lug contact, the primers were only slightly larger in dia inside the pocket, and craters looked no worse than the strikes around factory rounds in factory rifles. I saw absolutely zero evidence of pressure, yet the cases held what I am bettting was well into the mid 70K psi range. I even reloaded them and got 2-3 more firings on the pockets before I decided I was satisfied with my test of how well they held the pressure. I have never gotten to that high in a non-AI caliber (unless it had the 35-40* shoulders and very little if any taper to begin with) without a good list of signs saying "back off some... hotrod".
Not to say Ackelys are the be-all and end-all of the cartridge world, but I have found them to exhibit some very favorable symptoms, when run too high in the pressure arena. I am partial to the lessened stresses they seem to convey to the action when a load error is made, or in the case that your rifle likes it's load best, right at the pressure edge. Saving lug integrity is always tops on my list. Their straightness is responsible for group size, so setting them back or gauling them is not prefferable.
MHO, if you stick to no more than 60,000psi, you'll be fine. Remember, lots of the old chamberings still exhist in a lot of older military actions which will not hold pressures like todays rifles, so their load specs are conservative. Also, they may be based on older, less powerful propellants. And then some with the sharp shoulders will quite often run a bit higher in the pressure ranges.
as a general rule,..I would look to go no more than 1-2gr over any book max. If no harmonic can be found at those charge ranges, then your best bet is to settle for the harmonic exhibited further back down the load ladder and run with that one. Also, if you are using a min-spec or match chamber, you will most likely NOT reach a book max. The tighter chambers and nks, at least in my rifles, won't make it to book max before they are at max in these chambers. Be aware of this when moving to tighter chambers, especially in a match barrel blank that will also run a tighter groove dimension most of the time as well.
as far as 250+ fps increase, I got it in a match chamber in a 1:8 twist PacNor, so my internal tolerances were tighter than a rechambered factory bore. That may be the reason for increased velocity over others data. I was also running a bullet of ~.625BC which means a long bearing surface and more of a seal creating a higher and faster pressure curve also adding to the velocity increase. However, when you can get to 3208fps with a 140gr a-max in a 6.5-06AI out of only a 26" tube, you are wayyyyyyyyy overpressure. That is NOT arguable,..and when I saw the chrono reading from the first string, the remainder were taken home for de-construction. The cases exhibited not the slightest increase in bolt lift in a sako action that was making great lug contact, the primers were only slightly larger in dia inside the pocket, and craters looked no worse than the strikes around factory rounds in factory rifles. I saw absolutely zero evidence of pressure, yet the cases held what I am bettting was well into the mid 70K psi range. I even reloaded them and got 2-3 more firings on the pockets before I decided I was satisfied with my test of how well they held the pressure. I have never gotten to that high in a non-AI caliber (unless it had the 35-40* shoulders and very little if any taper to begin with) without a good list of signs saying "back off some... hotrod".
Not to say Ackelys are the be-all and end-all of the cartridge world, but I have found them to exhibit some very favorable symptoms, when run too high in the pressure arena. I am partial to the lessened stresses they seem to convey to the action when a load error is made, or in the case that your rifle likes it's load best, right at the pressure edge. Saving lug integrity is always tops on my list. Their straightness is responsible for group size, so setting them back or gauling them is not prefferable.
MHO, if you stick to no more than 60,000psi, you'll be fine. Remember, lots of the old chamberings still exhist in a lot of older military actions which will not hold pressures like todays rifles, so their load specs are conservative. Also, they may be based on older, less powerful propellants. And then some with the sharp shoulders will quite often run a bit higher in the pressure ranges.
as a general rule,..I would look to go no more than 1-2gr over any book max. If no harmonic can be found at those charge ranges, then your best bet is to settle for the harmonic exhibited further back down the load ladder and run with that one. Also, if you are using a min-spec or match chamber, you will most likely NOT reach a book max. The tighter chambers and nks, at least in my rifles, won't make it to book max before they are at max in these chambers. Be aware of this when moving to tighter chambers, especially in a match barrel blank that will also run a tighter groove dimension most of the time as well.
laportecharlie
New member
Steve Timm writing in Varmit Hunter Magazine convinced me that I had to have a 280AE and that Darrel Holland in Oregon was the guy to build it. My LH Browning stainless stalker had a "Boss" which reduced the actual barrel to only 20". Holland installed a 26" Schneider barrel in a #4 contour and trued up the action. Using Hornady 139 gr SST bullets the velocity went from approx 2700 fps to a mean velocity of 3241 and a SD of 12 with the longer AE barrel. The gun will now shoot in the fives all day long if I pay attention. The gun will shoot any factory ammo with no problem. With what I payed for the used but very nice gun & scope plus the cost to rebarrel it, I now have approx $1500.00 in the rig. I love it dearly but if I had it to do over, I would buy a Remington 700 in 7mm SAUM and get virtually identical ballistics in a factory medium action rifle for about one half the cost and without the six month wait. Oh well, live and learn (I hope!)
Charlie
Charlie
Longcruise
New member
Quote:
MHO, if you stick to no more than 60,000psi, you'll be fine. Remember, lots of the old chamberings still exhist in a lot of older military actions which will not hold pressures like todays rifles, so their load specs are conservative.
I think you could safely say and do just that. After all, what is it about the 30/06 case that is able to handle 61,000 psi when squeezed to a .270 winchester. Answer, IMO, is that it's probably perfectly safe to load your '06 AI to 60,000. OTOH, there is no reason why you can't load your '06 to 60,000 either.
So... we come right back to a direct comparison that has yet to be made. What is the performance gain between an '06 loaded to 60,000 and an '06 AI loaded to 60,000?
MHO, if you stick to no more than 60,000psi, you'll be fine. Remember, lots of the old chamberings still exhist in a lot of older military actions which will not hold pressures like todays rifles, so their load specs are conservative.
I think you could safely say and do just that. After all, what is it about the 30/06 case that is able to handle 61,000 psi when squeezed to a .270 winchester. Answer, IMO, is that it's probably perfectly safe to load your '06 AI to 60,000. OTOH, there is no reason why you can't load your '06 to 60,000 either.
So... we come right back to a direct comparison that has yet to be made. What is the performance gain between an '06 loaded to 60,000 and an '06 AI loaded to 60,000?
Longcruise
New member
I guess I'd also want to ask how would one know when they are at 60,000 PSI. I know there are no end of methods of reading pressure, but the fact is that ammo manufacutrers have readjusted their load data over the years as pressure measurement methods improved.
If you are waiting for your primer pockets to loosen or for a given amount of expansion in the case webe or looking for a shiney spot from the ejector plunger hole, you are going over pressure when you get there. So, how do you reliably know hoiw far to back off?
It's a crapshoot if you don't have effective pressure measurement.
If you are waiting for your primer pockets to loosen or for a given amount of expansion in the case webe or looking for a shiney spot from the ejector plunger hole, you are going over pressure when you get there. So, how do you reliably know hoiw far to back off?
It's a crapshoot if you don't have effective pressure measurement.
James Lindley
New member
Longcruise.. Velocity and pressure are two different critters all together..
If you run them (06 and the Ai)at the same pressures then the only gain that you could expect would be case life as the design of the Ackley case is to improve the life of the case by (like has already been said) nearly stopping neck stretch etc. The straighter walled design exerts more pressure on the chamber walls than thrust on the bolt face.
If you run the same velocity between the two then you are at less pressure with the AI case than you are with the parent 06. Therefore you are still preserving the case.
If you go to the same pressure... You have increased your velocitiy by (according to your test quoted) by 66 feet.
If you go ahead and push the AI round to show and exihibit the same pressure signs as exhibited by the 06 , you should gain a little more velocity.. This is where things get tricky. Will you?? I don't know because I don't have one handy to test.
It will not be the same for every case because of the original case design or the parent case being used. I can't tell you whether or not the 06 will bring more velocity than the ai (doubtful) but because of the design I'd bet on the AI case reaching greater velocities a lot easier than the 06.
Since not just every Tom, Dick, and Harry has all that fancy expensive pressure testing equipement, we have to rely on someone else testing that way for us..
No two barrels are the same and no two guns of the same caliber will take the same pressures..
SAAMI max pressures are industry standards that allow the use of modern loading prctices in some very old guns and still assure that they will not blow up in your face..
60000 in one might just shove the bolt back through your face in the next one..
But I would lay my money out and bet that it wont be the Ackley because of the way that it is designed.
In reloading I have never been one to really push the envelope on velocity. I did on a couple occassions but I'll plead temporary insanity..
Increased case life is a good incentive to convert a caliber to AI as it will deffinatley save money in the end.. James L..
If you run them (06 and the Ai)at the same pressures then the only gain that you could expect would be case life as the design of the Ackley case is to improve the life of the case by (like has already been said) nearly stopping neck stretch etc. The straighter walled design exerts more pressure on the chamber walls than thrust on the bolt face.
If you run the same velocity between the two then you are at less pressure with the AI case than you are with the parent 06. Therefore you are still preserving the case.
If you go to the same pressure... You have increased your velocitiy by (according to your test quoted) by 66 feet.
If you go ahead and push the AI round to show and exihibit the same pressure signs as exhibited by the 06 , you should gain a little more velocity.. This is where things get tricky. Will you?? I don't know because I don't have one handy to test.
It will not be the same for every case because of the original case design or the parent case being used. I can't tell you whether or not the 06 will bring more velocity than the ai (doubtful) but because of the design I'd bet on the AI case reaching greater velocities a lot easier than the 06.
Since not just every Tom, Dick, and Harry has all that fancy expensive pressure testing equipement, we have to rely on someone else testing that way for us..
No two barrels are the same and no two guns of the same caliber will take the same pressures..
SAAMI max pressures are industry standards that allow the use of modern loading prctices in some very old guns and still assure that they will not blow up in your face..
60000 in one might just shove the bolt back through your face in the next one..
But I would lay my money out and bet that it wont be the Ackley because of the way that it is designed.
In reloading I have never been one to really push the envelope on velocity. I did on a couple occassions but I'll plead temporary insanity..
Increased case life is a good incentive to convert a caliber to AI as it will deffinatley save money in the end.. James L..
chuckaholic
New member
I don't know. I don't think you can save enough cases via extended case life during a barrels life span to pay for a proper Ackley conversion. Today there are so many cartridges available in almost every caliber in baby steps that the chasing of performance really has no merit except in maybe a few cartridges. Why bother with a 30 06 AI when there are the 300 WM's, WSM's, and Weatherbys available? What will a 30 06 AI do at 400 yards that a 30 06 won't. Same holds true for almost any other caliber. 250 Savage,257 Roberts,25 06, 257 Weatherby. Not to mention the 224's. If you want it, its available. Not that I'm against messing around with AI's for being a enthuseist and clean fun. But I don't believe there are performance or money saving reasons that can stand the test of reasoning these days.
Case life and lug integrity as well as the redirecting of plasma to a more centerline flow in the throat, ability to use factory ammo in a pinch, etc etc. These are all gains, however some folks don't shoot to the degree where some of these advantages are benefits. The case life issue matters not if you don't have a tight chamber where brass is match prepped (lots of time of yours).
also, you don't by AI rifles out of the box. But, if you are chambering a barrel anyway, why not go AI for the same price and pick up the benefits.
That's my .002"
also, you don't by AI rifles out of the box. But, if you are chambering a barrel anyway, why not go AI for the same price and pick up the benefits.
That's my .002"