Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Rifles, Bullets, Barrels & Ballistics

Rifles, Bullets, Barrels & Ballistics Applied Ballistics


Reply

Ackley Improved

 
LinkBack Thread Tools Display Modes
  #8  
Old 05-10-2009, 11:54 AM
Gold Member
 
Join Date: Apr 2006
Location: Alberta
Posts: 856
Re: Ackley Improved

I had read on another board that AI chamberings generate less pressure than their parent cartridges. Is there any truth to this? Eventhough the AI has more powder in it is it more efficient due to the changes in the case dimensions??

Can anybody speak to this for me?

Thanks All!
Reply With Quote
  #9  
Old 05-10-2009, 03:02 PM
Junior Member
 
Join Date: Dec 2008
Location: southwet wa.
Posts: 20
Re: Ackley Improved

Quote:
Originally Posted by ICANHITHIMMAN View Post
Just my two cents but if your going to leave it un scoped and use it as a brush gun why go to all the truble of pushing the bullet so much faster?

You will have shorter barrel life and feeding could be an issue in the springfield. Aslo I am no metal guru but I do know that the old 06 is safe for that much presure.

I think one of the smith could awnser that.

Good point, I'm sure someday I'd run prolly a Grandslam in 4.75. Never know when a guy might poke an elk out around 300yds.

I'd not AI the springfield. Just plain old 338-06 with Lyman peep sight.
__________________
BD



"Thou shall hunt where there are trophy muledeer, or forever be plagued with mediocrity"
Reply With Quote
  #10  
Old 05-10-2009, 03:20 PM
Silver Member
 
Join Date: Apr 2009
Location: western Oregon
Posts: 120
Re: Ackley Improved

Quote:
Originally Posted by Slopeshunter View Post
I had read on another board that AI chamberings generate less pressure than their parent cartridges. Is there any truth to this? Eventhough the AI has more powder in it is it more efficient due to the changes in the case dimensions??

Can anybody speak to this for me?
Thanks All!
Generally "no." They will however generate less bolt thrust. That is, the straighter case walls (less taper) are credited with gripping the chamber better and as a result, less rearward force is exerted on the bolt.
As far as overall pressure goes, in the earlier cartridges, P.O. ran more pressure than factory loadings. The reduced bolt thrust supposedly gave him a larger safety window.
Later loadings, such as the .257 Roberts+P made up for most of the gains of early Ackley chamberings. There are still advantages to most Ackley chamberings though. Especially the more unique ones.

I have a chambering of the 6.5x.257 Roberts Ackley with the 40* shoulder that is my favorite. P.O. referred to the round as the .260AAR. AAR stands for all around rifle. It is one amazing round. .270 performance, 6-10 fewer grains of powder and .243 recoil. Very efficient, 150-200 FPS higher velocity than the .260 Rem, just as accurate and handles the really long 6.5 bullets better due to it's longer neck.

Hope that helps.
Reply With Quote
  #11  
Old 05-10-2009, 05:29 PM
Platinum Member
 
Join Date: Jun 2007
Location: Wilmington NC
Posts: 4,222
Re: Ackley Improved

The reason I said get your own reamer is simple, there are variations of almost every Ack Imp cartridge and they vary from 35 to 40 degree shoulders and different degrees of body taper.

We know of at least 7-8 variations of the 300 Ack Imp and no one set of dies marked 300 Ack Imp will work with all of them with any expectation of accuracy and long case life. Now if your smith can furnish a reamer print, you can call that reamer mftr and find out if a die company uses the corresponding resize reamer for their dies. If so, then you can use the gunsmith reamer and that mftr dies.

The key is matching the chamber reamer with the die reamer.

BH
Reply With Quote
  #12  
Old 05-10-2009, 06:29 PM
Gold Member
 
Join Date: Dec 2001
Posts: 800
Re: Ackley Improved

Quote:
Originally Posted by BountyHunter View Post
The reason I said get your own reamer is simple, there are variations of almost every Ack Imp cartridge and they vary from 35 to 40 degree shoulders and different degrees of body taper.

We know of at least 7-8 variations of the 300 Ack Imp and no one set of dies marked 300 Ack Imp will work with all of them with any expectation of accuracy and long case life. Now if your smith can furnish a reamer print, you can call that reamer mftr and find out if a die company uses the corresponding resize reamer for their dies. If so, then you can use the gunsmith reamer and that mftr dies.

The key is matching the chamber reamer with the die reamer.

BH
I argree there can be lots of caliber called Ackely Imp/Ackley mag etc but most like myself we understand that there has to be a parent case. Why would anyone build a Ackley chamber rifle not know what the parent case is. Anyone can pull up this site and see the difference click on dies and see how many listed under 300 etc.

You can get a reamer print really doesn't mean much if it's not headspaced right. Last time I check Neil still want a fired case
http://www.neiljones.com/html/full_l...zing_dies.html

Don't want to get into a contest with you we just have different was of doing things. Let see I've got a 222AI, (2) 223AI,(2)6RemAI,(2) 22-250AI,243AI,280AI may do another 280AI. I did a 30 on the Nosler 280AI case,6x250AI,7x57AI,338 on a 270AI case plus others like 17 on 222AI case 7-08AI.

I may be wrong but building a die from the chamber reamers may bump the shoulder back but doesn't FL size a case I assume that's one reason Neil want some fired cases here anothe site talks on FL die http://accurateshooter.wordpress.com...s-custom-dies/

Last edited by TOM H; 05-10-2009 at 07:03 PM.
Reply With Quote
  #13  
Old 05-10-2009, 08:29 PM
Silver Member
 
Join Date: May 2007
Location: California
Posts: 458
Re: Ackley Improved

I have custom PD rifles for 22-250AI, 243AI, and 220 Weatherby Rocket, and, IMO, the extra steps required fire-forming (by whatever method), and then working up accuracy loads for the AI cases is just not worth the ballistic improvement over standard chamberings.

If I had it to do all over again, I think I'd just stick with the standard chamberings.

OTOH, maybe I'm just getting impatient and crotchety in my old age.
Reply With Quote
  #14  
Old 05-11-2009, 11:14 AM
Platinum Member
 
Join Date: Jun 2007
Location: Wilmington NC
Posts: 4,222
Re: Ackley Improved

Tom

Slight misunderstanding here. I am not saying try to build a FL sizing die from the chamber reamer. As you point out it cannot be done and yes Neil Jones still needs 5 cases fired 3X to build a set of dies. He is building two sets for me now. I can get a custom honed and matching die set without buying a resize reamer and still paying to chamber a set of dies by using Neil Jones.

Yes, the gunsmith has to know how to properly headspace an AI chamber. I assumed that was a given.

What I am saying is that many guys/smiths have "tweaked" the AI chamber reamers for AI cartridges to their specs but still call them AIs. That makes them different specs than what has been deemed original AIs but the reamer and barrel are still routinely marked XXX Ack Imp. My question is simple "How do you know if you have the original AI chamber or a modified AI chamber?"

I used the 300 AI as a specific example with a known wide variance in different AI reamers and multiple AI die sets, most radically different in body taper and shoulder angles. Yes, you can even use multiple parent cases also in this chambering so some AIs can use multiple parent cases. Depending on which one you use effects the case OAL and trim length to make sure you do not end up with a big gap between the end of the case and end of chamber.

You can match up chamber reamers from the maker with die mftrs with a phone call or email to make sure that you get an exact match.

As many have pointed out, the AIs can be extremely efficient or extremely overbore and inefficient. PO Ackleys books run down the list.

BH
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Ackley Improved
Thread Thread Starter Forum Replies Last Post
7mm stw ackley improved?? dodgefreak8 Rifles, Bullets, Barrels & Ballistics 7 01-24-2013 11:02 PM
Ackley improved or Ackley changed north of 53 Rifles, Bullets, Barrels & Ballistics 10 10-19-2008 03:49 PM
.270 Win Ackley Improved? Death Ray 7 Rifles, Bullets, Barrels & Ballistics 5 03-13-2008 03:53 PM
30-06 Ackley Improved Wind Dancer Rifles, Bullets, Barrels & Ballistics 11 02-11-2005 10:02 PM
243 Ackley Improved Terry Brady Rifles, Bullets, Barrels & Ballistics 5 11-01-2003 02:05 AM


All times are GMT -5. The time now is 02:47 PM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC