Question about Ackley Improved

BigDon

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Oct 2, 2018
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145
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Cheyenne, Wy
I have had a .257 AI and now a 6mm AI - 40* shoulder.

My gunsmith likes to cut the chamber slightly short so I get a crush fit the junction of neck & shoulder when fireforming - tight fit, essentially no headspace when fireforming. For subsequent loads I use a shortened shell holder to maintain correct head space.

I use whatever pistol primers I have available and whatever pistol powder I have, When fireforming, I start at 10% of the total capacity load then work up so I get nice sharp shoulders.. Coffee grounds (dry) sound good for a filler vs. cream of whatever. Like, if 60 grains of pistol powder fills the case to the top of the neck, I start with 6 grains, the last FF session used 9 grains of HP38.

Dies are available for popular AI calibers. My 6mm Lee collet neck sizer works with 6mm AI brass. I have a Redding 6mm AI F/L sizer die (stock item) and I use a generic 6mm Hornady seating die. Necks are turned to .268 diameter. My brass is adequately fireformed at chamber pressures of about 60K PSI - this is after COW fireforming using full charge loads with bullets. I would not select any AI cartridge that required custom dies - $$ - just me.

With the 6mm AI the case capacity is increased about 10% resulting in 80-100 FPS increase, case stretching is almost nothing, feeding is excellent in my Ruger M77 MKII LA rifle. COAL is right around 3 inches depending on what bullet I use. I planned on getting a 8 twist 6mm AI on a FN commercial Mauser but gave up on the idea when the intended rifle would not feed dummy 6mm AI rounds because the shoulder hung up on the top collar inside the receiver ring - that rifle was re-barreled to 6mm-06.

I use my 10 twist 6mm AI with 87 grain VMax bullets & H4350, RL16,or IMR4831 against rodents - real good performance - 600 yards and beyond. Many 3 shot clover leaf groups and under 2 inches at 300 - good enough for me.

The generic Hornady seater die is used for; .243W, 6mm Rem, 6mm AI & 6mm-06. Brass diameter at the shoulder is of no consequence.

Just remembered - under 10* & snowing - time for a Dickel & fireplace (gas).
I have had a .257 AI and now a 6mm AI - 40* shoulder.

My gunsmith likes to cut the chamber slightly short so I get a crush fit the junction of neck & shoulder when fireforming - tight fit, essentially no headspace when fireforming. For subsequent loads I use a shortened shell holder to maintain correct head space.

I use whatever pistol primers I have available and whatever pistol powder I have, When fireforming, I start at 10% of the total capacity load then work up so I get nice sharp shoulders.. Coffee grounds (dry) sound good for a filler vs. cream of whatever. Like, if 60 grains of pistol powder fills the case to the top of the neck, I start with 6 grains, the last FF session used 9 grains of HP38.

Dies are available for popular AI calibers. My 6mm Lee collet neck sizer works with 6mm AI brass. I have a Redding 6mm AI F/L sizer die (stock item) and I use a generic 6mm Hornady seating die. Necks are turned to .268 diameter. My brass is adequately fireformed at chamber pressures of about 60K PSI - this is after COW fireforming using full charge loads with bullets. I would not select any AI cartridge that required custom dies - $$ - just me.

With the 6mm AI the case capacity is increased about 10% resulting in 80-100 FPS increase, case stretching is almost nothing, feeding is excellent in my Ruger M77 MKII LA rifle. COAL is right around 3 inches depending on what bullet I use. I planned on getting a 8 twist 6mm AI on a FN commercial Mauser but gave up on the idea when the intended rifle would not feed dummy 6mm AI rounds because the shoulder hung up on the top collar inside the receiver ring - that rifle was re-barreled to 6mm-06.

I use my 10 twist 6mm AI with 87 grain VMax bullets & H4350, RL16,or IMR4831 against rodents - real good performance - 600 yards and beyond. Many 3 shot clover leaf groups and under 2 inches at 300 - good enough for me.

The generic Hornady seater die is used for; .243W, 6mm Rem, 6mm AI & 6mm-06. Brass diameter at the shoulder is of no consequence.

Just remembered - under 10* & snowing - time for a Dickel & fireplace (gas).

I looked at the Hornaday site and did not find a ‘generic’ seating die. I’m just edging in to AI and would appreciate your clarification on exactly which die you are using.
 

scope-eye

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Nov 9, 2009
Messages
792
Location
FL
I use several seating dies and not even caliber specific, I just find one that does not mark or mar the bullet and since I don't crimp it dosn't really matter.

Dean
 

scope-eye

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Nov 9, 2009
Messages
792
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FL
They Only Rreason I Ackley Improve a chamber is for they increase in powder charge from they extra case capacity. The cases never seem to last long enough to have to trim them or take advantage of some of they other benefits this chambering offers.

Dean
 

7stw

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Jan 21, 2010
Messages
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Location
Salisbury Maryland
I looked at the Hornaday site and did not find a ‘generic’ seating die. I’m just edging in to AI and would appreciate your clarification on exactly which die you are using.
Redding makes a standard die ser fo my 25.06ai. I also have a body die, (thanks Bro Bean), and now have Lee collet die, and FCD. When weather straightens up, gonna put it all to good use, along with some awesome Lapua brass.
 

GLTaylor

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Oct 11, 2019
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1,834
Location
Cedar Bluff, Al
They Only Rreason I Ackley Improve a chamber is for they increase in powder charge from they extra case capacity. The cases never seem to last long enough to have to trim them or take advantage of some of they other benefits this chambering offers.

Dean
Guess I don't run my AI cases too hard. I've got 3 boxes on their 7th to 9th loading. Course I do anneal. The 9th loading primer pockets are probably close to done?
 

Hugnot

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Sep 26, 2020
Messages
736
Location
Montana
I looked at the Hornaday site and did not find a ‘generic’ seating die. I’m just edging in to AI and would appreciate your clarification on exactly which die you are using.
Look at some site like Midway for .25-06 Hornady seating dies.

This will work:

Screenshot (106).png

I use the 6mm version on .243W, 6mm Rem, 6mm AI, & 6mm-06

Upon seating a bullet a the neck of the cartridge is inserted into floating sleeve that aligns the bullet with the mouth of the cartridge. Only the brass neck goes into the die. The same die would work for .257 R & .257 Weatherby. Get the stock number & let your fingers go shopping on-line or back order from MIdway. Die parts may be swapped to convert these dies to other calibers. Hornady might be willing to sell die parts or possibly an entire Hornady die set might need to be acquired. I have a bunch of these nice seaters. Various seating stems to match bullet ogives are availble.
 
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Hugnot

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Sep 26, 2020
Messages
736
Location
Montana
Some photos:
IMG_1401.JPG


The Hornady seater is in the middle left and to the left of the die, right to left: 6mm-06, 6mm AI. 6mm Rem, .243W. The same die upon adjusting in press will seat 6mm bullets in all 4 cartridges.

Nothing new? At the right center is an antique .30 caliber Vickerman seater die having a spring loaded sleeve with a loading window to hold and guide .308 diameter bullets into a seating stem that is partially visible. To the right of the Vickerman die are a .300 WM and .308 round. The stubby short .308 round is perched on top of an extension to allow the brass neck to reach up into the bottom of the Vickerman seater. Many .30, 168 Sierra & 168 Hornady bullets were loaded for .308W match shooting some 54 to 60 years ago using the Vickerman seater ( the window speeds things up). Many 190 Sierra Match Kings and other .30 bullets have also been loaded into .300 WM loads from then to recently.

The 6mm bullets are: 105 AMax in .243 W & 6mm-06, 105 Hornady hpbt in 6mm, and 87 Vmax in 6mm AI.

I am still working on a moderate size stash of 6mm 105 AMax bullets.

The .30 bullets are 178 ELDM in .300W and 125 Speer TNT (bang-zip-splat) in .308W.

Two dies seat bullets for 6 cartridges.
 
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7stw

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Jan 21, 2010
Messages
2,234
Location
Salisbury Maryland
Some photos:View attachment 252686

The Hornady seater is in the middle left and to the left of the die, right to left: 6mm-06, 6mm AI. 6mm Rem, .243W. The same die upon adjusting in press will seat 6mm bullets in all 4 cartridges.

Nothing new? At the right center is an antique .30 caliber Vickerman seater die having a spring loaded sleeve with a loading window to hold and guide .308 diameter bullets into a seating stem that is partially visible. To the right of the Vickerman die are a .300 WM and .308 round. The stubby short .308 round is perched on top of an extension to allow the brass neck to reach up into the bottom of the Vickerman seater. Many .30, 168 Sierra & 168 Hornady bullets were loaded for .308W match shooting some 54 to 60 years ago using the Vickerman seater ( the window speeds things up). Many 190 Sierra Match Kings and other .30 bullets have also been loaded into .300 WM loads from then to recently.

The 6mm bullets are: 105 AMax in .243 W & 6mm-06, 105 Hornady hpbt in 6mm, and 87 Vmax in 6mm AI.

I am still working on a moderate size stash of 6mm 105 AMax bullets.

The .30 bullets are 178 ELDM in .300W and 125 Speer TNT (bang-zip-splat) in .308W.

Two dies seat bullets for 6 cartridges.
Me like😁
 

scope-eye

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Joined
Nov 9, 2009
Messages
792
Location
FL
Just so you know, you can and will cause erosion to the throat by just fireforming, probably even more
since there is no bullet to dampin they ignited load of powder that is burning directly into the throat like an acetylene torch. You can still enjoy shooting while fireforming so why not, infact I have had a couple of barrels that shot better fireforming than formed cases so, I just kept forming one was a 260AI and they other was a 25-06AI. I just used the formed brass for my 6-06AI and 243AI, and lastly a fired case with no bullet will not form as nice or uniformly as one fired with a bullet, it could and usually takes a couple of firings to form a case properly without a bullet. This is just my experience from forming tens of thousands of cases over the years, take it for what it is worth.

Dean
 

nkyshooter

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Joined
Sep 16, 2014
Messages
478
Location
Northern Kentucky / Cincinnati
Two dies seat bullets for 6 cartridges.


The Frankford Arsenal Universal Micrometer Seater will seat all rifle cartridges from 22 up to 33 caliber (regardless of shoulder slope, wildcat, ackley or not) though I don't know if it can handle the case diameter of oversized magnums (Norma, Lapua, etc) ...

This die provides ample adjustment and multiple seating stems as well to permit seating from pretty much any length cartridge from a very short short 6BR up through 3.850 CIP length. These stems also allow seating of VLDs without deforming the tip/meplat.

I got mine for $75 - last I checked, Midway had them in stock ...

Here is the Frankford Arsenal webpage on it ...

 
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