Ack Improved Cartridges

[Jeff H]

ACK Improved Is not worth it for us guys , Ben..............

Yeah, after this thread, I think my mind's made up too. I wasn't all for or all against before, given that my dad is so pleased with his 257 Roberts Improved, but I stayed with the original for a reason - like I said before, I can turn 3000FPS+ on 100 grain bullets and 3300 fps+ on 75 grain bullets, and without straining the brass/gun/self, nor am I using a lot of powder. I can't imagine needing anything more out of a 75 grain HP based on what woodchucks look like after getting in front of one that started at 3300 fps.

As far as "long action"/"short action," I'm pretty much in the middle with my Mausers, which are perfect for the 55mm and 57mm cartridges - go figure. When I was fire-forming brass, bullets and powder were a lot cheaper and I had time to spend doing it too.

 

[Brad]

Ackley improved cartridges aren’t in general cast friendly anyway. The extra powder space is often a hinderance for us, not a blessing.

 

[Ben]

The extra powder space is often a hinderance for us, not a blessing.

My exact thoughts.
That is the reason in post # 1 that I mention that I walk away from them when I see them.

Ben

 

[Brad]

The 30-30 AI wouldn’t be bad. It could actually do well with cast with full loads. The others are strictly a full tilt proposition. Kinda like why buy a sports car to drive 45 on the highway.

 

[fiver]

they don't work with buffers or fillers too nice either.
they do have other advantages though.

such as holding a bullet square to the barrel, even if it is a little low, it is facing the right direction, and not tilted or pulling the nose straight in the crooked neck.
they also do better with a bit more of a slightly slower powder [better case fill on a longer case which holds more powder against the primer] for the same velocity.

the 7 Ackley I built for the wife was the one I never touched a case with a reloading die.
[punched the primers, re-filed with some 4895 or 2400 and pushed the bullets in place]
I was pushing 30 reloads on those cases when she got rid of it.
I just re-formed them back to the standard shape and annealed them and we now use them in Littlegirls rifle for hunting loads.

 

[Bret4207]

The AI's have their place. In the 50&60's they were about the cheapest way to get some real performance boost, just like all those other wildcats. These days you can factory buy what an Ackley/Epps/etc will do for less than what the Ackely conversion will run. Times change. But, if you had a burning desire for a 99 Savage 25-35 walking varmint rifle or a #4 Lee-Enfield in 6.5/303 those were the guys you went to.

 

[Rootmanslim]

There's a facebook group on AIs. Most have really drunk the Kool Aid. They have no pressure transducers and believe it's ok to run a 30-06 AI at 70K PSI. Had one tell me his 06AI was = to a 300 winmag ! So I sent him the Nosler data showing the 300 was 300fps faster. He's gone silent. I have one, a 280 built on an X-bolt that shoots well and (with 26" bbl) can touch 3000 w/140s BUT I also have a 1958 M54 Schultz and Larsen in 7x61 S&H (also 26") that is a tad faster and way cooler. The X Bolt will be sold when I return to the Equality State in June.

 

[fiver]

the 0-6 AI would be a waste of time, pretty much any of them on the 0-6 case is a total waste of effort.
the 280 being the dumbest iteration of the bunch, especially the way rem/nosler done it.
it's actually unbeneficial to the round and to Parkers name being associated with that worthless travesty of brass.
anyone that jumped on that bandwagon needs a lesson in case design.

just to illustrate a few things.
you could always AI the 300 H&H etc. for the next step in getting real gains from the process but Weatherby already done that and disguised it with round shoulders.
I have a 257 Bob with the double radius[ish] shoulders and it's a lot more accurate than it should be considering, but it certainly isn't going to rival my 25-06 for speed just from a shape conversion the gun wouldn't take it.

you have to use some common sense here.
is a 61mm case that already has enough powder in it to waste 10-20% of it even after a trip down a 24" barrel going to really gain anything?
no it ain't,,, you might as well just jack up the pressure on the regular case.
but is a shorter case gaining more powder volume to get closer to that of the 61mm case going to benefit?
yes it will and the shorter the case with the most taper to it the 'better' the benefits in most umm cases.

 

[JWFilips]

I was a big fan back in my early days ! (always trying to get to 4000 fps) !Now they are meaningless to me

 

[fiver]

they ain't all about speed JW.
the case shape is fairly closely mimicked in the 6.5 creedmore and even closer in the 6mm and 243X.
the 243X is the hot target round in this area, it's basically a slightly shortened 243 case with Ackley shoulders on it so you use 243 reloading data.
I'm not gonna try to beat it with anything I got.

 

[Pistolero]

For some cartridges, better headspace consistency, sure. In most cases all the gains are from raising
pressures, not from "more efficient shape" which I think is about 98-99% myth, over the
range of normal modern bottleneck cartridge geometries.

Could you invent a 4" long .22 straight case versus a 2" long bottleneck shape where the combustion
chamber shape would make a difference? Sure, maybe. But a tiny bit of shoulder shape diff
that many have make some significant diff in burning efficiency? I am very skeptical.

Barsness has tested some short fat modern carts against long skinny old carts......nothing to be found
just in the shape, it seems. Why do you think pretty much all of the hot new SSMag and such are all
just gone, most (all?) no longer cataloged? Because they don't actually do anything better than the
cartridges that we already had.

But better, more consistent headspace because of a better shoulder shape is a real issue for some cartridges,
and some of the AIs have very significant case volume increases, which is not bad. But the ones with a ~5%
volume increase where the parent cartridge has a nice shoulder size and angle......probably little or nothing there.

Look at the powder charge that a 7mm Mag needs to push the same bullet as a 7mm-08 just about 10-15% faster.
140 gr 7-08 uses 46 gr of W760 to make 2800 fps, the 7mm Mag uses 60 grains of the same powder to make
just under 3000 fps. 30% more powder required to make 7% more velocity. Now with slower powders, and
much more of them, you can go faster, a compressed charge of IMR8133 78 gr will make 3200 fps. So now
we have 1.70 times as much powder to get a velocity gain of 14% in velocity.

So, if your AI will let you burn, say 10% more powder (and I think most AIs do less, but haven't looked in
great detail) if 30% makes 7% more velocity, I'll bet 10% more will make about 2.33 % more velocity (at the same
pressures).
The 70% increase of a slower powder gets 14% more velocity, so using that ratio, 10% more
powder space might get, 1/7th of 14% ----2% more velocity at the same pressures. I imagine that AI folks,
KNOWING that they have to have higher velocity, just pump up the pressures and get that
expected gain mostly from pressure increase.

Hate to not believe in the AI Easter Bunny, but the laws of physics and all.....

Bill

 

[JWFilips]

closer in the 6mm and 243X.
the 243X is the hot target round in this area, it's basically a slightly shortened 243 case with Ackley shoulders on it so you use 243 reloading data.
I'm not gonna try to beat it with anything I got.

I 'm familiar with that an few earlier variants That is where I was in the 1980's It was a dream un fulfilled !
Thanks fiver for reminding me

 

[fiver]

good points Bill.
the shoulder shape does influence how a powder burns and influences gas flow to the barrel more than most think.

you know just adding a slight sloping shoulder to a black powder case raised the pressure @2,000 psi.
that doesn't seem like much but BP is burning at what 14-K.

the same thing carry's over to smokeless somewhat but in a different form it [sharp square shoulders]actually makes the powder burn faster.
the first thing I mention to someone wanting to Ackley something is to first be prepared to get back to where he was and then start working his loads with a step slower powder from that point onward.
they aren't just a bigger case where you dump 5 more grains of whatever powder you were using in them before and go on with your day.

 

[Pistolero]

I remain skeptical that the shoulder shape has a signifcant effect on burning
smokeless powders. I am not dogmatic about it not being true, just skeptical,
have seen some evidence that it is not a significant factor and little or no evidence
that it is a significant factor.

Always willing to learn from real evidence.

Bill

 

[Rootmanslim]

OMG the case shape myth again. I thought Handloader put this to bed years ago when they did the 300 WSM vs 300 H&H test.

from 2011:

"Finally, in the new Handloader, is the data that proves to any intelligent reader, that the classic 300 Holland and Holland or Super-Thirty is in all ways equal to the 300 WSM and in several, superior.
And please no whining about "short stroking".... a myth perpetuated by people who never were properly trained in shooting a bolt action rifle. Only seems to be a problem with belted H&Hs but I never hear it about 300 RUMs..... odd as they have same case length.
Guess those Brits back in 1920 were smarter than some "experts" (then & now) thought."

"The .300 H&H has almost exactly the same powder capacity as the .300 Winchester Short Magnum, and handloads attain just about the same velocities. In a 24-inch barrel you can safely get 3,000 fps, but not 3,100. This despite the vast differences in case shape, which supposedly allows the .300 WSM case to burn powder much more “efficiently.”

(actually no Magnum should have a 24" bbl as Remington and Winchester knew that back in the day when 300 H&Hs came w/26" bbls.)

All P.O. did was stuff more powder behind the bullet ----- that's all (unless you count crappy feeding as an improvement)

 

[Ian]

The WSM and H&H do not have anywhere near the same powder capacity. That article only proved one test, devised by one set of people, and limited by their creative ability at devising comparative experiments. Browning shows a 180 grain bullet at 110 fps faster than the H&H that boasts ten percent more case capacity. For all intents and purposes you or anyone could prove that comparison either way based on optimizing the load for EACH CARTRIDGE and EACH PLATFORM.

Ask a benchrester who KNOWS, "Why the 6mm PPC?"

 

[Rootmanslim]

82.6 gr 300 H&H, 76 gr 300 WSM.
Fastest Nosler 165 gr load, 300 H&H 3200, 300 WSM 3300 both with 24" bbls.
If loaded to same pressure,with appropriate powders, in a 26" bbl, as 300 WSM, 300 H&H blows it away.
With heavier bullets the gap widens as you can't get unuf powder in the 300 WSM (like 308 vs 30-06)
Then we have the greased banana feeding vs the pop up out of the magazine issue. (seen in happen in M70s in WSMs)
The H&Hs have been around forever. All the WSMs save one are as dead as SAUMs, RSMs, WSSMs and so on.

I actually fooled with a 270 WSM for a while. Silly thing, O'Connor would toss it off the cliff.

Hey shoot whatever you want but when the big bad thing that can kill you is heading your way H&Hs have been saving butts for a century.

No plastic, no pot metal, 300 H&H. (barrel is too short though)

400 H&H

375 H&H

 

[Bret4207]

Root, my faith in what Handloader says all depends on who wrote it and when. I've seen some stuff in there by some of the hack writers that is not anything like my experience. Not all of them , but a few.

Bill, one place the AI series shines is with the 25/35. I know, it's old and slow and funny shaped and the brass stretches like crazy. Cut the chamber to AI and the brass stretching disappears, the powder capacity is increased and you can take a 117 bullet from 22 or 2300 fps up into the 26-2700 area or more with far less back thrust and pressure. With an 100 gr you tread on the heels of the 250-3000 and with varmint bullets it's even closer. They ahve their place.

 

[Pistolero]

Bret, no argument in those kind of cases. Much like the Hornet going to K-Hornet. Much better headspace
and much increase in case volume, percentage wise. I have no problems with that. and I believe that is
the area where he made his real strides forward.

But a .280 vs .280 AI......an already well shaped and well proven case ('06) gains maybe 3-5% in volume
and then the magical shoulder ......I don't buy it at all in those ones. I refer back to my 7-08 vs 7 mag
numbers above. Not any 'there' there, unless you pump up the pressures.

Bill

 

[Rootmanslim]

Actually it was Rifle not Handloader. (my error). And the results were beyond dispute.
The rimmed cases, headspace on the rim not the shoulder. The K Hornet and rimmed AIs make sense of you have a single shot build that can't handle rimless cases. Like resurecting a non collectible low/high wall or similar. Otherwise there are factory cases to do the same. Anyone who would AI a classic high condition 99, Low or High Wall deserves flogging. I own a wonderful solid frame 99 rifle in 22 HP. I'm sure it would be "better" if "AIed" but it aint gonna happen. The scope is mounted in a unique no drill mount that uses the tang sight holes and the bbl dovetail.