Hello
I’ve wanted to do this for a while now. Take a bullet and run as many powders over it as I can get a hold of, and see what the rifle really likes, instead of dictating to the rifle what it will shoot. The rifle is a Belgian FN 98 Mauser action, glass bedded and free floated. This rifle has a rather long throat so I found 3.130” to be the best with most loads. That length is represented in the targets below.



First, let me tell you that this 7x57AI barrel was made and installed by Chick Donnelly here is Southern Oregon. He set up shop under the name of Siskiyou Gun Works. Chick is the protégé of P.O. Ackley himself. He had all of P.O. Ackley’s tools and reamers.
In my mind, there is no better authority on how to ream an Ackley chamber.
A few years ago, Chick passed away on Christmas Day. He was a wonderful man and is missed very much.

Now, I’d like to talk about the Ackley chamber itself. What it is, and what is isn’t.
The 7x57 in a strong action is loaded to a pressure of 50,000 CUP in the current manuals.
So what should the 7x57 Ackely be loaded to? Unknown, it’s a wildcat.. But for the sake of argument let’s assume it’s loaded to the same 50,000 CUP. Without pressure measuring equipment, how to we arrive at this?

Well let’s look at some brass facts.
Privi Partisan 7x57 new brass, with a seated spent primer, has a water weight of 59.6grs. If it was fired in a std chamber the water weight might be around 59.8-60.0grs. So let’s call it 60.0grs. If someone can fill this gap in, please do..
Fire formed Privi brass in the Ackley chamber has a water weight of 64.0grs. That is a net gain of 4grs.. Maybe 4.2grs.. Or, a 7% gain in powder capacity.

My premise is, a 7% increase in volume would necessitate a 7% increase in powder charge to equal the 50,000 CUP pressure. (Boyles Law).. Well let’s see what the targets indicate.

I’m using the Sierra 160gr Spitzer BT bullet and Privi Partisan cases. Temps are on the cool side. Groups are shot at 200 yards.
I’m just sharing what I have so far… I still have some work to do. There are a few more powders to work with, and I’m going to re-shoot with different charges and primers.

Bolt lift was beginning to be an issue at the end of the ladder in most cases. And accuracy deteriorated as charges increased based on previous work.



Rx22.. A bit disappointing..
W780.. Shoots better in warmer weather
H-414.. Didn't like CCI250 primers. Will try WLR primers next. Adj scope up and left during this ladder.





HUNTER.. Would have like to have started at 49.0grs
4000-MR... Try a different primer




Rx 19.. Good groups all the way through. Will re-shoot out to 53.0grs




Fresh work with IMR4831 and N-160. Will re-shoot N-160 out to 52.0grs.
A re-shoot of Rx17 and Rx22.
Rx17.. 48.5grs shot better this time..
Rx22.. Bolt lift issue at 54.0grs


Still to try..
AA4350
H-100V Hybrid







W780 shoots better in warmer weather.




For the most part, ‘accuracy loads’ occurred in the 2500fps range with this 160gr bullet.
Accuracy loads were roughly 7% over what a standard 7x57 would shoot well?

BTW, Winchester Ackley fire formed brass holds 63.4grs of water so Privi and Win are very close. I also get bolt lift difficulty with Win brass with the same charges. So I don't believe Privi heads are any 'softer' than Winchester.



Anyway that’s what I have so far.

Good work. That's what it takes--lots of time and industry.

Dave Manson

Here is the latest work with Hybrid 100V..



Highest velocity load that is fairly accurate so far..

You are testing loads by .5 grains. Have you ever though of testing by .2 or .3 grains? Your groups show barrel timing problems. You may want to experiment with that.

As you develop loads, have you ever wondered why your groups come together, then fall apart, then come back together again?

Gain in vel, at same pressure, is 1/4 of the gain in capacity, expressed in percent

Take a 10% larger case, run at same pressure results will be 2.5% gain in vel

Boyle's law doesn't apply here, as velocity isnt linear, it's work, or area under the time pressure curve. Want to call me out on that? What happens if you shoot 10 rounds in a 24" barrel, then cut it down to 17 inches? If pressure alone had jack to do with velocity, then nothing would change

If you gain more than 1/4 of the % increase n capacity, you are running pressure up. I am an avid reader of ackley, and if you read his work, he recognizes that straight cases SHOW less pressure, but are still under pressure

All that being said, best of luck and be safe

quote:

Originally posted by MickinColo:
You are testing loads by .5 grains. Have you ever though of testing by .2 or .3 grains? Your groups show barrel timing problems. You may want to experiment with that.

As you develop loads, have you ever wondered why your groups come together, then fall apart, then come back together again?

Hello
Yes.. As I understand barrel vibrations.. I'm just a student in all this and trying to understand more.. The idea in all this is to find a combination of components where the bullet exits the barrel at the same place on the vibration curve, thereby creating the tight groups we are looking for. I've also heard this referred to as the 'sweet spot'. There can be more than one sweet spot in a given ladder.

Now why I go with .5grs at a time, is mostly economic.. I don't have an endless budget to buy components, so I cheat a little and cover as much ground with as little components expended as possible.

Now what I will do, say with the Hybrid 100V for example, is shoot .2grs ladder between 48.2 and 48.8grs and see what happens.

Now after all this is figured out at a coolish temperature, 35-45°F, what happens if I shoot all this at 75°F? It will most likely change..

So is this what you mean by 'barrel timing problems'?

quote:

Originally posted by jeffeosso:
Gain in vel, at same pressure, is 1/4 of the gain in capacity, expressed in percent

Take a 10% larger case, run at same pressure results will be 2.5% gain in vel

Boyle's law doesn't apply here, as velocity isnt linear, it's work, or area under the time pressure curve. Want to call me out on that? What happens if you shoot 10 rounds in a 24" barrel, then cut it down to 17 inches? If pressure alone had jack to do with velocity, then nothing would change

If you gain more than 1/4 of the % increase n capacity, you are running pressure up. I am an avid reader of ackley, and if you read his work, he recognizes that straight cases SHOW less pressure, but are still under pressure

All that being said, best of luck and be safe

Nah, don't want to call anyone out.. This is my first Ackley rifle and just wanting to understand whats goin on here.. What is the relationship between a standard 7x57 case/chamber and the new improved case/chamber, and what can I realistically expect. And I know Boyles Law doesn't apply directly, just wanted to start a conversation.
Can you give me an example with this cartridge of ¼ of the % increase in capacity?

I have seen some loads for the 7x57 AI on the net, that some say they use, that if shot in this rifle, pressures would be horrendous. So I wanted to show what actually shoots well in a properly chambered rifle and, that the loads are well under some of the posted loads.

I put all this data in a graph so I could see it all at once, and it's amazing how each powder/primer combination reacts. Some had very even climbs in velocity, some were slow to climb then larger gains at the end, one, W780, actually went backwards a few times.. I don't think it likes cold weather, because this powder actually shoots very well in warmer weather.

So anyway, thanks guys for chiming in

Btw, your audette ladder work is to be commended!

here's a great example
300 win v 300 weatherby

6 grains difference, or about 7 % SHOULD result in about 1.7% diference in vel -- if at the same pressure, however, the weatherby runs at higher pressure.. about 5% higher, and is generally shot from 2" longer barrel.

let's assume 25fps for each inch (actually, its likely to be more)
adding the 6% increase in case capacity + 5% higher pressure, thats 11 (no units)
11/win cpacity (assumes pressure as baseline) results in 12.7 ish
divide 12.7/4 = 3.1% difference
1+.031 = 1.031 (factor, unitless)
1.031* winchester factory loads (assumes 180gr at 2960 data from hornady) results in
about 3054fps .. hornady lists the weatherby-50fps for 2" barrel difference, at 3070 with 180gr bullet (3120 raw data)

which is pretty darn close to 1/4 of increase results in velocity ..

it worse backwards in pressure, as well...
the 416 weatherby is SLIGHTLY larger than the 416 rigby (3.7gr) but runs at HUGELY more pressure.. -- backing into it, about 50% more pressure.. which is actually about correct.. 44 vs 65k

which is about the delta in vels listed in factory ammo ...

ANY gain, without a very large change in general design, of more than 25% of capacity increase should be associated with an increase in pressure .. an exception is my 458 Accurate Reloading as compared to the 458 lott .. it has slightly more capacity, however it si structurally different in that it has a STRONG shoulder for venturi .. my 470 AccRel has a weaker shoulder, and doesn't match (by a couple FPS) the vel gain over the 470 capstick, which is it a few % larger than ...

I did a 7x57AI way back when Ruger first came out with the 7x57. The throat was so long 160 and larger grain bullets just barely hung in the case. I NEVER did get it to shoot the way I wanted, but it did OK as far as hunting accuracy was concerned...2-3". I still have the dies, rusting, but the barrel is long gone and the Ruger Tang had a succession of barrels and is now my 510 Makatak.

John Barsness wrote an excellent article in either Rifle or Handloaders magazine quite a while back that covers all the aspects and HOW's that he came up with that formula...basically a lot of work with ballistics tables and a calculator.

You calculate pressures and velos by comparing many different cases with similar case volumes...by inspection of ballistics tables. You can also calculate the different pressures between caliber sizes vs case size...or between caliber sizes in the SAME case, i.e., 243 vs 7mm vs 30 vs 35 cal, etc., in a 308 case, or '06 case or any other step increase in cal vs a specific case size.

Both PO Ackley and Powely, of Powley's formulas that are used in many software programs for calculating INTERIOR BALLISTICS and "The Powley Papers", have written many excellent articles and books on Ballistics and reloading.

Those three authors are the place to begin if you want to understand Ballistics in general and Interior Ballistics(what is going on between the bolt face and the muzzle when a round is fired) plus a bit of physics.

Actually Boyles law does apply, but more certainly Charles laws and combining the two with Avogadros law into the "Ideal gas law" makes more sense, but WAY beyond the average user unless he happens to have a laboratory full of goodies.

The next step in your process would be to benchrest prep your cases, bench prep your bullets, pick the load with the smallest group and see if benchprepping actually did help. Then shoot a 10 round group to see just what happens.

I have shot many bughole 3 shot groups(all bullets touching is my concept of a "bughole" no matter what the caliber) with bench prepped case and components, reload the SAME three cases and shoot them again within about 15 minutes, in almost the same conditions and have the group open up maybe one to 1 1/2 calibers larger.

Not just one time, but many, many times over 30-40 years and several rifles and cartridges. It can make you totally crazy, especially when you're benchresting and have a winning target going.

Basically you want to reshoot all those small groups AND some of the large groups to see if they repeat.

You should see by now that changing components can alter group size, basically, by altering barrel vibrations which spits the bullet out at different points in the dispersion cone.

Studying the targets shows you that a change in the amount of powder can cause a vertical thru horizontal dispersion to happen and when things are right you get a nice equilateral triangle.

If that triangle stays after firing another 3 shot group then you can maybe get the group to go larger or smaller by seating out longer or in shorter.

The main reason for a step by step increments is to bring the group to the smallest point where the next increments starts to open the group up.

Then you change ONE component at a time. Always clean between strings when you change a component and fire a few foulers.

It takes a lot of work. You are "breaking in" a new barrel as you go which can have an effect, that may or may not be seen fully unless you have found that bugholer right off.

Every aspect of the system from bench, to bullet, to rifle system, to how many cups of coffee you had before shooting, to the time of day, sun angle, YOUR health, etc., can affect your targets...so make copious notes and always repeat those "bughole" groups to see if they are flukes or real.

You're doing great...keep it up.

Luck

quote:

Nah, don't want to call anyone out.. This is my first Ackley rifle and just wanting to understand whats goin on here.. What is the relationship between a standard 7x57 case/chamber and the new improved case/chamber, and what can I realistically expect. And I know Boyles Law doesn't apply directly, just wanted to start a conversation.
Can you give me an example with this cartridge of ¼ of the % increase in capacity?

Starting back in the late 70s I started playing with AIs and my own blown out wildcat. I took the same 280barrel with strain guages from 280-280AI 7JRS and my own 280PDK. As best as I could measure the gain was 1 for 4 at equal pressures. Several others with pressure measurement (that I could afford) gave the same. What I found was in an 06 based case 1 for 4 was a very good rule of thumb. The 7x57 seemed to give just a touch more the 308 based just a touch less. So min to max 1 for 3 to 1 for 5. So I use a 1 for 4 as my rule.

As even Ackley stated the reduced taper hides pressure doesn't make it go away. What I found often happened was a load would look safe and 1/2gr powder increase would blow my primer.

The 7x57 and 257R over the years have always claimed use gains from AI for the most part they are comparing to factory lower pressure loads then taking the pressure up to 65,000+.

In a 7x57AI with a 160 going from 60,000 to 65,000 will gain you 75-100fps.

All that said I shoot more blown out wildcats or AIs than std. Enjoy your 7x57AI you are heading down the right direction as to load developemnt just remember the pressure signs you see in a 7x57 might no show up until too late on the AI version.

Thanks guys for the thoughtful replies.. Much appreciated.

http://forums.accuratereloadin...2511043/m/8241081861

Here is a Quickload readout based on the parameters I gave to Antelope Sniper regarding HUNTER. That accurate load, 50.0grs, came in at 49,700psi.
At 51.0grs I began to feel a resistance in bolt lift, so I didnt continue.
Not to consider QL as the last word here, but it was pretty close..

One thing about this Mauser action, appearantly when loads approach 55,000psi I get bolt lift change. I'm going to accept this to mean, do not go any further..

From what I've gathered so far with 160 and 175gr bullets anyway, there doesn't seem to be much if any velocity gain over the standard chamber. I know a few guys that shoot 7x57 and their ballistics are pretty close to what I'm getting with equal barrel lengths.

So in order to see any velocity gain, higher pressures must be used.

Anyway, thanks again.. I'll keep pluggin away

look over the rl-19 again.
my 7 ackley really like it.
53.2 grs and a rem 9-1/2 primer in the rem case with a 139gr bullet does about what you are getting there at 52 grs.
i wasn't going for full tilt velocity.
just good accuracy in the velocity that the bullet would work best for hunting.
i was using win primers to do initial load work with, and stopped as soon as i tried the remington primers in the next phase of testing.

Seems strange to have blot lift issues at 55000. Other signs?

In order my powder choices would have been:
MRP
N560
Rl22
7828
Rl19.

quote:

Originally posted by ramrod340:
Seems strange to have blot lift issues at 55000. Other signs?

In order my powder choices would have been:
MRP
N560
Rl22
7828
Rl19.

Other signs.. I've noticed that the cases that took the loads out to heavy bolt lift, primer pockets were a little looser than the others.
These Privi cases have very uniform pockets when new.

MRP.. Not available here locally. Would have to order it on-line from somewhere. I would like to order some more Norma 201 for my 222 Rem and .358 Win.

N560.. Worked with it before a few years ago. I got some outstanding groups with it, but velocities were quite slow compared to other powders.. Not sure why this was.. And I noticed that velocities, at the end of the ladders, would come to a stop and go backwards as the charges went up to max. Hit the wall, so to speak..

Rx22.. Not a stellar performance with WLR primers. Could try another.

Rx19 did quite well I thought. All except one group was under 2". Human error is always at play.. But I will re-shoot it out to 53.0 grs.
I got a feelin that 52.0, or thereabouts will be the one.

The powders that surprised me were HUNTER and Rx17.

With HUNTER, I should have started at 49.0grs.

Rx 17 is supposed to be designed with the short mags in mind, which have fairly straight walls and 35° shoulders. Similar to the Ackleys. So I guess it would make sense that it would like this case.

quote:

Rx19 did quite well I thought

I run a lot of RL19 from the wifes 7x57. Have never played that much with RL17. Have you ever tried a different brand of brass?

Yes, I have used Rem, Win, and some Herters that I picked up on ebay back when you could..
I use Win the most, but since the Privi brass had the most capacity, I used them for this latest test, thinking I would get the most performance. And this is the first time I spent THIS MUCH time and effort with this rifle.

Remington runs about 60grs of water
Win runs about 63.4grs water
Privi runs at 64.0grs water

Remington will max out quickly, but a few years back I found a load with Rem brass that is very accurate.
150gr Nosler Partition ahead of 52.5grs H-450, WLR primer. 3.130" OAL. I friend of mine gave me a lb. since he had no use for it. However when that is gone.. well, find something else. I only use these for hunting. Three deer have fallen to that load.
I think it would be worthwhile to do this again with Rem brass with a lighter bullet maybe..

The Herters brass.. well I loaded up some fireforming rounds and when I tried to chamber one, wouldn't fit. Discovered the necks were too thick. Had to take a few thousands off all the cases. After successful fireforming I found them to hold .5gr more water than a standard 7x57 unfired Rem case.
So I developed a load with 120gr Sierra spitzers. IMR4320 came out on top. The load was the same as a max load of 4320 in a standard case.

Well the So Oregon winter has arrived at last.. so shooting will be whenever there is a break.. not very often..

quote:

Discovered the necks were too thick

With your pressure signs almost sounds like your chamber neck is a touch tight.

quote:

Originally posted by ramrod340:

quote:

Discovered the necks were too thick

With your pressure signs almost sounds like your chamber neck is a touch tight.

I suppose it's possible.. Never had a chamber casting done or had it looked at that closely.

But then, if a fireformed case only holds about 57grs of water, it's THICK..

quote:

But then, if a fireformed case only holds about 57grs of water

Fireformed none resized? I think my wife's 7x57 are larger than than before resizing.

I was acutally looking for where I wrote down that info to get specifics, but I do remember that a fireformed Herter case with the spent primer still in, held just a tad more water than an unfired Rem 7x57 case with a spent primer seated to hold the water.
It was rather ridiculous how thick those cases were.

I was expecting something like a NORMA case but this stuff was unusual, even though the box says, 'made in Sweden'.

And yes, the weight was with fireformed cases, not resized.