HuntingNut
HuntingNut
   Login or Register
HomeCommunity ForumsPhoto AlbumsRegister
     
 

User Info

Welcome Anonymous


Membership:
Latest: RichardZ
New Today: 0
New Yesterday: 1
Overall: 13126

People Online:
Members: 0
Visitors: 169
BOT: 1
Total: 170
Who Is Where:
 Visitors:
01: Home
02: Forums
03: Forums
04: Forums
05: Photo Albums
06: Forums
07: Forums
08: Forums
09: Home
10: Your Account
11: Forums
12: Home
13: Home
14: Home
15: Forums
16: Forums
17: Your Account
18: Photo Albums
19: Forums
20: Home
21: Forums
22: Forums
23: Your Account
24: Forums
25: Forums
26: Forums
27: Photo Albums
28: Forums
29: Home
30: Your Account
31: Forums
32: Photo Albums
33: Home
34: Forums
35: Forums
36: Forums
37: Your Account
38: Forums
39: Photo Albums
40: Forums
41: Your Account
42: Photo Albums
43: Forums
44: Photo Albums
45: Forums
46: Home
47: Home
48: Home
49: Forums
50: Forums
51: Forums
52: Your Account
53: Your Account
54: Photo Albums
55: Forums
56: Forums
57: Photo Albums
58: Forums
59: Home
60: Forums
61: PointBlank Ballistics
62: Forums
63: Forums
64: Photo Albums
65: Forums
66: Home
67: Home
68: Your Account
69: Forums
70: Forums
71: Forums
72: Home
73: Your Account
74: Your Account
75: Forums
76: Your Account
77: Home
78: Photo Albums
79: Forums
80: Your Account
81: Forums
82: Home
83: Forums
84: Photo Albums
85: Home
86: Your Account
87: Forums
88: Forums
89: Your Account
90: Forums
91: Forums
92: News
93: Forums
94: Forums
95: Forums
96: Forums
97: Forums
98: Home
99: Forums
100: Forums
101: Forums
102: Forums
103: Home
104: Forums
105: Forums
106: Forums
107: Forums
108: Forums
109: Photo Albums
110: Forums
111: Your Account
112: Forums
113: Forums
114: Home
115: Forums
116: Forums
117: Photo Albums
118: Your Account
119: Your Account
120: Forums
121: Home
122: Forums
123: Home
124: Forums
125: Home
126: Forums
127: Forums
128: Photo Albums
129: Home
130: Your Account
131: Forums
132: Forums
133: Your Account
134: Photo Albums
135: Home
136: Forums
137: Forums
138: Forums
139: Home
140: Your Account
141: Forums
142: Forums
143: Your Account
144: Forums
145: Forums
146: Forums
147: Forums
148: Forums
149: Your Account
150: Your Account
151: Forums
152: Home
153: Forums
154: Forums
155: Photo Albums
156: Forums
157: Forums
158: Photo Albums
159: Forums
160: Photo Albums
161: Photo Albums
162: Forums
163: Forums
164: Forums
165: Forums
166: Forums
167: Forums
168: Forums
169: Home
  BOT:
01: Photo Albums

Staff Online:

No staff members are online!
 

Coppermine Stats
Photo Albums
 Albums: 308
 Pictures: 2451
  · Views: 820723
  · Votes: 1316
  · Comments: 86
 

  Forming AckleyImproved Brass

ReloadingOver the last thirty years or so building rifles and reloading, one subject that comes up frequently are the Ackley improved or more to the point ,what is the correct way to form brass. I'll get into some details and ramble on a bit, but I think in the end it will make sense.

( NOTE...I'm neither a writer or good picture taker. The old saying "A picture speaks a thousand words" applies .....)

The design is such that factory or handloaded ammo can be safely fired in an improved chamber. In reality,they are not ture wildcat cartridges. Wildcats are considered a rifle for which no factory loaded ammo exists. A 6.5-06 would be an example. The 6.5-308 was a wildcat for many years until Remington standardized it,now known as the 260 Remington. The 7mm-08 is another example. The term "improved" is a round reconfigured by fireforming,but where both ammo and chambered rifle exist.

With that, lets look at a typical AI cartridge. First, the shoulder is typically moved to a steeper angle, 40 degrees the most common, second, the body taper is reduced to a minimun spec,normally .010" case web to the shoulder and third, the neck-shoulder junction is moved back. This is a picture of a formed AI and parent cartridge, a 22-250 and 22-250AI.


The method to form AI brass is actually quite simple by firing factory or handloaded ammo,but I need to make a few comments first.

We all hear about the term "Headspace". A black art or a mythical process to some, but in my opinion, its simply a piece of brass trapped between two unmoveable pieces of steel. I believe in the K.I.S.S. principle.
Headspace is normally the distance from the boltface to a point on the case shoulder known at the "Datum" for a bottleneck rimless cartridge,however there are other ways to acheive it. As an example,when the 204 Ruger hit the market factory brass was at a premium, more costly than gold I think. One work around was to reform 222 Rem. Mag brass, the parent of the 204 R. Since I had a supply of left over 222 RM brass,by partically resizing the neck in the 204 die creating a "false" shoulder and fireforming, I made 204s. My load for the 204 is 29.5-BLC2 with a 32 grain bullet, the forming load,28.0-BLC2 and a 32. As to why that forming load I'll get to later. Take notice of the shoulder position between the 222 RM and 204 cases.


Another method of headspacing as used to form AI brass is the neck-shoulder junction. The design of a true improved places the junction back from that of the parent round. The reason for that is when a factory case is chambered the only contact is with the boltface and the junction. Remember, the AI chamber has a straighter body and steeper shoulder angle, so the casehead and shoulder-neck junction points are the only place a factory case will make full contact. As a side note, the orginal spec for the 30-06 was the same, casehead to neck-shoulder junction, not the datum!

Here are three examples, a 22-250AI,250-3000AI and a 270-308AI next to the parent cartridge. All three parent cases were randomally selected from lots of brass, right out of the bag except the 270,which was necked to 27 from 308 brass only.

Notice,in all three examples, the location of the neck-shoulder junction.

Here are the three parents,smoked to show where they headspace in the AI chamber. The bright ring indicates contacts the chamber wall or zero headspace.


Next, the parent, a chamber cast and a formed 250-3000AI case.


The pictures show the correct method for headspacing a factory parent to form improved brass. When the factory round is chambered there will be a slight crush fit if the chamber was cut correctly.

Now, if the chamber was cut correctly and is in fact a true AI, there are two way to make brass. One, simply fire factory loaded ammo of you choice, the other, handload forming rounds. Now, regardless of the opinions,thoughts,ideas and rumors what charge to use, the correct one is a stiff charge for the parent round. As an example, for my 22-250AI I shoot a load of 39.5 - Varget, the forming load is 36.0-Varget, both with a 50 grain bullets. That 36 grain load is just under the top for a 22-250 listed in the Sierra manual.

Although some suggest and get away with a reduced load to form brass, from expericence, I don't recommend it. A reduced load may casue "bouncing" effect and not fully form the case. (P.O. Ackley words) Although appearence wise it looks perfect, they can be as much as .030" short causing a casehead or top shoulder seperation. In my 30 some odd years using AIs I have seen this time after time. About a year ago, a showed me a case with a complete shoulder seperation from a 243AI. It happend on the second firing He had formed the using a light load for the 243 Win. Measurements of the formed brass showed they were .005 - .0015 short. I made a chamber cast to confirm the chamber dimensions, loaded a new batch of ammo and they formed exactly right. Lesson learned.

Another miscomception is a bullet jam. A bullet will not provide headspacing, it moves! Remember my defination of headspace, a brass case between two "unmoveable" pieces of steel? A bullet will begin moving before the case can expand 100%. I've heard of the firing moving the case forward when the primer is struck. If this happens,the case is too short, or the chamber is too long. I'll say it again, "a factory case will headspace on the neck-shoulder junction in a correctly chambered barrel".
I continue mentioning "correctly" chambered.. There are those that simply re-ream an existing chamber to convert to an AI without setting back the barrel. This creates a chamber longer than a true improved. Remember the AI is longer from the casehead to the top of the shoulder and shorter at the neck-shoulder junction than the parent round. For a 22-250 - 22-250AI the measurements are....

(22-250 22-250AI)
Casehead to shoulder ............ 1.514" ... 1.524"
Casehead to neck - shoulder .. 1.664" .... 1.644"
Overall length ....................... 1.912" .... 1.892
Top shoulder diameter ............ .414" ..... .454"

Using these measurements, you can see why setting back the barrel is required. If you thinking of having the conversion done,ask how the job will be done . If it doesn't include the setback, find another 'smith...quick! I made that mistake with my first one,a 280AI. Another gunsmith did the job over, correctly.
At times a reamer is cut to a special specs, ie..freebore,neck diameter,etc. Ask for the reamer specifications before having the job done. Its always a good idea to have the 'smith test fire the rifle and supply a few fired cases. The last few I've put together have been fully threaded and chambered Savage barrels. To headspace them, I use a factory unsized case. The 22-250AI and 250-3000AI in the pictures were done using factory brass and fireformed. In fact, all my Savages have be setup this way, AI or otherwise.

After forming, reloading for an AI is exactly the same as any other catridge and caution should be used in working up a loads as one would normally do.

Now, some may agree,disagree or have other opinions This is what I've been taught, do and have formed thousands of rounds without a problem.

Well, I hope this helps those thinking the AI route. They are not the problem some make them out to be. The benifits are a higher velocities and extended case life if loading is kept within reason, but one more step in the process of reloading.


Take care !

Bill

Posted by BillPa on Saturday, April 08, 2006 (16:27:17) (15694 reads) [ Administration ]
Related Links
 More about Reloading

Most read story about Reloading:
OCW ( Optimal Charge Weight )
 

Article Rating
Average Score: 4.75
Votes: 8


Please take a second and vote for this article:

Excellent
Very Good
Good
Regular
Bad

 

 

Valid CSS! Valid HTML 4.01!
Click to check if this page is realy HTML 4.01 compliant for speed :)

All logos and trademarks in this site are property of HuntingNut.com.
The comments are property of their posters, all the rest © 2011 by HuntingNut.com
Interactive software released under GNU GPL, Code Credits, Privacy Policy

.: Upgraded to DragonFly 9.2 by *Dizfunkshunal* :.