Ack Improved Cartridges
- Thread starter Ben
- Start date
RicinYakima
High Steppes of Eastern Washington
Totally depends upon what cartridge you are starting with. With one with a lot of slope to the body, 250 Savage or 22-250, it is noticeable. The rule of thumb is that a 4% increase is powder capacity will get you 1% increase in velocity. 308 Winchester, not very much. IMHO.
Missionary
Well-Known Member
Good morning
We have an old interesting 1886 someone added a AI 33 Winchester barrel to. Only reason I bought it was to get the action. Maybe an increase in 100 FPS but sure does nothing to help accuracy wise with cast. Just more wear and tear on brass. But that was back when the power mania was just getting rolling.
We have an old interesting 1886 someone added a AI 33 Winchester barrel to. Only reason I bought it was to get the action. Maybe an increase in 100 FPS but sure does nothing to help accuracy wise with cast. Just more wear and tear on brass. But that was back when the power mania was just getting rolling.
Spindrift
Well-Known Member
Interesting question!
In some AI cartridges, you seem to get an increase in velocities that is out of proportion to the increase in powder capacity alone (like the. 30-06 AI). This would indicate a change in powder burn efficiency. My gunsmith (who is also a former international level BR competitor), claim the sharp shoulder and more cylindrical powder column increase accuracy potential. But, at the end of the day, I have all the speed and power I need, and my guns already shoot better than me.
My view of the Ai cartridges is, they are theoretically interesting cartridges, offering no practical gains, and necessitating the aquisition of expensive special dies. So, like you, I'll pass I think.
In some AI cartridges, you seem to get an increase in velocities that is out of proportion to the increase in powder capacity alone (like the. 30-06 AI). This would indicate a change in powder burn efficiency. My gunsmith (who is also a former international level BR competitor), claim the sharp shoulder and more cylindrical powder column increase accuracy potential. But, at the end of the day, I have all the speed and power I need, and my guns already shoot better than me.
My view of the Ai cartridges is, they are theoretically interesting cartridges, offering no practical gains, and necessitating the aquisition of expensive special dies. So, like you, I'll pass I think.
KeithB
Resident Half Fast Machinist
I have a Turkish Mauser that I rebarrelled and rechambered to .257 AI. I was working on the stock when I started having health issues a few years ago so I set it aside. Need to finish the job up but it is on the list of things to do when I get time...
Always thought the .257 was a neat cartridge and the AI version seemed to be about all you are going to get out of a .25 in a standard length Mauser action. Nothing against a .25-06 but it seems like it is almost too much case for the caliber. (Now I've started a discussion!)
Always thought the .257 was a neat cartridge and the AI version seemed to be about all you are going to get out of a .25 in a standard length Mauser action. Nothing against a .25-06 but it seems like it is almost too much case for the caliber. (Now I've started a discussion!)
Ian
Notorious member
It can. IIRC Fiver has a 7mm AI that nips at the heels of much larger, higher-recoiling calibers. I read one of P.O. Ackley's books when I was a teenager and he had a very long, scientific explanation of the improvements, though I remember it sounding like a good basic idea with excess sales pitch thrown in. Paul has spoken fondly of his K-hornets, a very similar modification.
That's the whole point. The case shape changes the burn and allows a couple ticks slower powder to be used at good efficiency, thus longer burn and more FPS. I'm sure it's a lot more practical in some cases than others, as Ric pointed out.
Hawk
Well-Known Member
AI cartridges are wildcats and at the time, may have been worth it in some cartridges. Today, with the plethora of new, short and super short SAAMI approved magnum cartridges, they are more of a novelty and not worth the cost of custom dies.
But isn't that the whole concept of the short and super short magnum cartridges?
I know they are not necessarily revisions to existing cartridges, but they use the concept of a similar minimum body taper and sharper shoulder angle to get more from the cartridge than you would reasonably expect.
I don't know if Ackley was the first one to discover this, but it seems like he may have laid the ground work for a lot of todays new cartridges.
Just my 2 cents.
But isn't that the whole concept of the short and super short magnum cartridges?
I know they are not necessarily revisions to existing cartridges, but they use the concept of a similar minimum body taper and sharper shoulder angle to get more from the cartridge than you would reasonably expect.
I don't know if Ackley was the first one to discover this, but it seems like he may have laid the ground work for a lot of todays new cartridges.
Just my 2 cents.
Rootmanslim
Banned
There are 2 worth having.
The 30-30 AI and the 280 AI. The former reduces bolt thrust in lever guns and produces a real vel. gain. The latter can, with a 26" bbl come quite lose to the 7 mags with bullets of 140 gr and less. Gains have nothing do with case shape as HANDLOADER proved several years ago. The AI cases just hold more powder.
The 30-30 AI and the 280 AI. The former reduces bolt thrust in lever guns and produces a real vel. gain. The latter can, with a 26" bbl come quite lose to the 7 mags with bullets of 140 gr and less. Gains have nothing do with case shape as HANDLOADER proved several years ago. The AI cases just hold more powder.
Bret4207
At the casting bench in the sky. RIP Bret.
Read his books and what he got out them. I know with rounds like the 25-35 you can make big gains. IIRC the Ackley 25-35 jumps up into 250 Savage speeds at safe pressures. As Root said, 30-30AI you can see 150-200fps. Others it's not a big gain at all. In some he blew the shoulders way forward, in others he just straightened the case a lot.
RicinYakima
High Steppes of Eastern Washington
All of you are making good points but I think it gets down to, "I want one.", "Nobody in my group has one.", "Wow, that is really neat!".
30-30 - I've read a lot about it:
Sam Fadala wrote with much praise about the 30-30 AI, specifically in lever-guns and, if I'm remembering this correctly, experimented with shooting the 30-30 AI in a Winchester 94 with the bolt lugs removed to prove the point regarding reduced back-thrust. Aside from worthwhile velocity gains, he also noted a big increase in brass life. I've never had a 30-30 AI myself, but I don't shoot any 30 caliber jacketed, so I don't think I'd benefit from the alteration. Increased brass life and less back-thrust would be appealing to me but I don't even use all the case capacity as it is unless I use one of the 4350s.
257 Roberts - First-hand experience with a couple:
My dad and I have shot the 'Roberts and it's more modern twin, the 25 Souper side by side for years. He was getting worthwhile increases in velocity from some projectiles when he improved one of his chambers, but I don't remember which weight. He also shot the unmodified Roberts at very pedestrian velocities to begin with and his powder choices were based on a few he started shooting before I was born and hasn't ventured into "modern" powder formulations. I'm sure there could have been some optimization by considering other powders along with the volumetric increase. He still shoots one as his main rifle.
7x57 - First-hand experience with ONE:
I had a 7x57 Improved done up on a tang-safety Ruger 77 with a 24" Douglas barrel. Velocities I was getting were about equal to the highest velocities I've seen in some older reloading manuals for the 7x57 from 154 grain to 175 grain bullets. I clocked a whopping 2700 fps with some 120 grain HPs, but was using 3100 powder. Probably could have dine much better with another powder. The Hornady 162 grain Spire Point was the bullet I worked with the most and just barely made 2700 fps with those. We worked out of an old wildcat reloading manual (Lyman, I believe?) and some of the data shown for the 35 Whelan (before it was "legitimized" by Remington), the 257 AI and 7x57 AI, and especially the 25 Souper were very hot in my opinion. Many of the attractive increases in velocity seemed more by virtue of exceeding established pressure limits (very low in the case of the 257 and 7x57).
than from the extra powder capacity.
One especially annoying point on the 7x57 AI in the Ruger was that the plunger ejector would force the body of the case into the right lug race as the bolt was pulled back and it would hang up the bolt. Took some fiddling and cussing to dislodge and remove the fired case. Fixed ejectors in the Mausers never did that.
Sam Fadala wrote with much praise about the 30-30 AI, specifically in lever-guns and, if I'm remembering this correctly, experimented with shooting the 30-30 AI in a Winchester 94 with the bolt lugs removed to prove the point regarding reduced back-thrust. Aside from worthwhile velocity gains, he also noted a big increase in brass life. I've never had a 30-30 AI myself, but I don't shoot any 30 caliber jacketed, so I don't think I'd benefit from the alteration. Increased brass life and less back-thrust would be appealing to me but I don't even use all the case capacity as it is unless I use one of the 4350s.
257 Roberts - First-hand experience with a couple:
My dad and I have shot the 'Roberts and it's more modern twin, the 25 Souper side by side for years. He was getting worthwhile increases in velocity from some projectiles when he improved one of his chambers, but I don't remember which weight. He also shot the unmodified Roberts at very pedestrian velocities to begin with and his powder choices were based on a few he started shooting before I was born and hasn't ventured into "modern" powder formulations. I'm sure there could have been some optimization by considering other powders along with the volumetric increase. He still shoots one as his main rifle.
7x57 - First-hand experience with ONE:
I had a 7x57 Improved done up on a tang-safety Ruger 77 with a 24" Douglas barrel. Velocities I was getting were about equal to the highest velocities I've seen in some older reloading manuals for the 7x57 from 154 grain to 175 grain bullets. I clocked a whopping 2700 fps with some 120 grain HPs, but was using 3100 powder. Probably could have dine much better with another powder. The Hornady 162 grain Spire Point was the bullet I worked with the most and just barely made 2700 fps with those. We worked out of an old wildcat reloading manual (Lyman, I believe?) and some of the data shown for the 35 Whelan (before it was "legitimized" by Remington), the 257 AI and 7x57 AI, and especially the 25 Souper were very hot in my opinion. Many of the attractive increases in velocity seemed more by virtue of exceeding established pressure limits (very low in the case of the 257 and 7x57).
than from the extra powder capacity.
One especially annoying point on the 7x57 AI in the Ruger was that the plunger ejector would force the body of the case into the right lug race as the bolt was pulled back and it would hang up the bolt. Took some fiddling and cussing to dislodge and remove the fired case. Fixed ejectors in the Mausers never did that.
RicinYakima
High Steppes of Eastern Washington
" Many of the attractive increases in velocity seemed more by virtue of exceeding established pressure limits (very low in the case of the 257 and 7x57), than from the extra powder capacity."
I think that is a very true statement. When we tried to estimate pressure in the 1960's and 70's, it was very crude to say the least.
223 Remington MAP 52,000 CUP; 257 Roberts 45,000 CUP, 7X57 46,000 CUP and 30/06 50,000 CUP
I have been told that the normal 30/06 pressure for modern factory loaded ammo is about 44,000 CUP with improved powders and modern commercial chambers, and it meets listed specification.
FWIW
I think that is a very true statement. When we tried to estimate pressure in the 1960's and 70's, it was very crude to say the least.
223 Remington MAP 52,000 CUP; 257 Roberts 45,000 CUP, 7X57 46,000 CUP and 30/06 50,000 CUP
I have been told that the normal 30/06 pressure for modern factory loaded ammo is about 44,000 CUP with improved powders and modern commercial chambers, and it meets listed specification.
FWIW
Ian
Notorious member
A very smart choice IMO, the AI gives a more defined shoulder for headspacing.
I finally got a chronograph around '89 or '90, not long after the "Shooting Chrony" came out. For a while, my dad and I sent a lot of rounds over that thing and we got a lot of surprises on tried and true loads which were accurate and terminally effective for years. We'd work up to the "pressure signs" and back off a bit. That little red box-o'-truth hurt our feelings sometimes.
We almost always came up short of what velocity we thought we were getting, but I remember discontinuing the use of a certain 310 grain cast load in the 44 mag right about then too. Geez, cases nearly fell out of the chambers, so it couldn't be that hot, right? That's when I really came to respect the strength of the OM Super Blackhawk.
Are you doing that with your fire-forming load? I found the 7x57 and 257 AIs to shoot very well when fire-forming.
Have you been able to chronograph "before and after?" That one takes out a lot of body taper and the volume increase must be significant compared to many others.
Did I miss an intro somewhere? "scb" sounds familiar.
Welcome!
CZ93X62
Official forum enigma
I have P.O. Ackley's books on my garage shelf with my reloading manuals. Mr. Ackley was not coy about pouring in the powder. The A/I cartridges always seemed like me to be a "Bigger boiler = more steam = more velocity" matter to me, like the 30-06 vs. 308. (THERE is yer "fur-a-flyin'" discussion for ya!)
I did consider the 25/35 A/I re-chambering as a cure for the spoiled chamber I developed in my Win 94 25/35 WCF. P.O. Ackley stated in his "Manual" that post-war 25/35 cases did not fire-form successfully. I had a gunsmith somewhat lined-up to do the work, but he was honest guy--and crunching the numbers for custom dies, barrel work, and the labor-intensive work involved with forming cases......having JES Reboring turn the rifle into a 38/55 was about 1/3 the tariff, all-in. SIGN ME RIGHT UP. In appreciation, I had the gunsmith re-barrel my shot-out 22-250, and he did a GREAT job of it. Win/win, all around.
Since 90% of my rifle shooting gets done with cast bullets, the siren song of the Ackley Improved has little vigor for me. Creating MORE case volume seems to be moving counter-productively, and case life is already improved markedly by the reduced pressures involved with the poured projectiles.
I did consider the 25/35 A/I re-chambering as a cure for the spoiled chamber I developed in my Win 94 25/35 WCF. P.O. Ackley stated in his "Manual" that post-war 25/35 cases did not fire-form successfully. I had a gunsmith somewhat lined-up to do the work, but he was honest guy--and crunching the numbers for custom dies, barrel work, and the labor-intensive work involved with forming cases......having JES Reboring turn the rifle into a 38/55 was about 1/3 the tariff, all-in. SIGN ME RIGHT UP. In appreciation, I had the gunsmith re-barrel my shot-out 22-250, and he did a GREAT job of it. Win/win, all around.
Since 90% of my rifle shooting gets done with cast bullets, the siren song of the Ackley Improved has little vigor for me. Creating MORE case volume seems to be moving counter-productively, and case life is already improved markedly by the reduced pressures involved with the poured projectiles.
fiver
Well-Known Member
i have a few Improved rounds
not all improved rounds are Ackley, and there are several iterations of the same round.
i know of about 5 different iterations of the 7x57 alone, the 280 Ackley has a correct one and then the one Remington done [which is an abomination]
as a kid I knew Parker and hung around his shop a couple days a week [he actually wrote me a letter of recommendation to join the air force]
anyway there are some very good reasons for using an Ackley improved cartridge shape.
one is it lets you use a slower more case filling powder.
[the shoulder shape will speed up the burn about 1 step]
the case doesn't stretch, i usually just neck size and anneal for the first 10 loadings of the case.
not all case sizes actually gain much from being improved, but they are changed.
the x57 i have that Ian mentioned earlier is the one i kept, the original actual Ackley chambered rifle is the one i built into the XCB rifle.
the second is actually the ICL version with straighter case walls, and the longer neck length.
i have easily pushed 140gr bullets to 3,000+ fps with it, normally i run the Hornady 139gr SP at about 2900 fps.
but taking an old 45-K pressured round.
add about 12% case capacity and jack the pressure up to 270 pressures and you really brings things alive, or in the case of this rifle just the opposite.
now had i done a short neck version and pushed the case out further i could have gained another 2-3 grains of case capacity letting me burn about 57grs of something like 4831 pretty safely.
not all improved rounds are Ackley, and there are several iterations of the same round.
i know of about 5 different iterations of the 7x57 alone, the 280 Ackley has a correct one and then the one Remington done [which is an abomination]
as a kid I knew Parker and hung around his shop a couple days a week [he actually wrote me a letter of recommendation to join the air force]
anyway there are some very good reasons for using an Ackley improved cartridge shape.
one is it lets you use a slower more case filling powder.
[the shoulder shape will speed up the burn about 1 step]
the case doesn't stretch, i usually just neck size and anneal for the first 10 loadings of the case.
not all case sizes actually gain much from being improved, but they are changed.
the x57 i have that Ian mentioned earlier is the one i kept, the original actual Ackley chambered rifle is the one i built into the XCB rifle.
the second is actually the ICL version with straighter case walls, and the longer neck length.
i have easily pushed 140gr bullets to 3,000+ fps with it, normally i run the Hornady 139gr SP at about 2900 fps.
but taking an old 45-K pressured round.
add about 12% case capacity and jack the pressure up to 270 pressures and you really brings things alive, or in the case of this rifle just the opposite.
now had i done a short neck version and pushed the case out further i could have gained another 2-3 grains of case capacity letting me burn about 57grs of something like 4831 pretty safely.
Bret4207
At the casting bench in the sky. RIP Bret.
I think RicinYakimas points about pressure are noteworthy. One of the things I never understood was why when so many people were rebarreling '03 actions to hot numbers like the 257R they were advised to hold the pressure way down to Remington Rolling Block specs. I suppose it was the old version of a consumer protection bureau type of thing, but I bet a lot more Springfields, K98's and Arisakas got built into 257s than Rolling Blocks or 93 Mausers. And for that matter, the '91/93/95/96 Mausers were fine rifles that stood loads in Europe we never put them through here. Well, that's water under the bridge. Some of Ackleys or Epps (Canadian) improved rounds make a lot of sense to me.
Jeff- Sam Fadala, good writer, thanks for reminding me of him.
Jeff- Sam Fadala, good writer, thanks for reminding me of him.
Last edited: