Fire forming

bigdumboy

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Joined
Mar 23, 2011
Messages
223
Location
Shippensburg Pa
Ok these are some examples of the brass maybe just to worried about getting it right the first time. Comments would be helpful sometimes I over think things
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lancetkenyon

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Jun 3, 2013
Messages
3,917
Location
Arizona
I have had (and loaded for) a few Ackleys, and a bunch of other rifles with improved chambers in wildcats that emulate Ackleys.
.22-250AI
.243AI
.250AI
.25-06AI
6.5SLR
.260AI (and building another now)
6.5SS (×3 with 800+ rounds of fire forming)
6.5-.280AI
6.5-06AI
7SS
.280AI
.30-06AI
.300NMI

I seat jammed to lands .003". Moderate to top charge weight for the parent case in most instances unless they don't have a parent case. I usually get 95% or more formed cases. Enough that 2nd firing doesn't make hardly any changes.

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jdyoung

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Mar 1, 2020
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545
Location
Ironman Country
Given the current “here today, gone tomorrow” situation of retailer component stocks, I wouldn’t “waste” bullets by "Jam fireforming."
I would create a false shoulder and then use the COW method to fireform the cases . When you go to the range you can get down to business developing that accurate load.
Don’t forget to anneal.
 

del2les

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Joined
Oct 24, 2007
Messages
943
Location
South Central, CO
Lots of good info already posted, but I will throw in my experiences.

I've formed several AI's and other in my life, and I have used most every method posted. The COW and false shoulder with fast pistol powder saves components and throat wear, but also, I have used bullets jammed, lead and jacketed, with a proper load of pistol powder to reach the correct pressures (Lyman cast bullet manual helps). Also, I have loaded with hunting/target bullets and a top end load of rifle powder and used those loads to practice at the range, varmint shoot, etc, etc. Many times, they are very accurate even in the forming stages, so I did not feel I had wasted the components.

With today's component shortage/costs and if one does not have a fair stockpile on hand, I would lean more toward the COW-pistol powder method for initial forming. YMMV
 

FEENIX

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Dec 20, 2008
Messages
17,635
Location
Great Falls, MT
Ackley's design concept is to able to shoot factory loads. In my .270 AI rifle, I have accuracy load for .270 Win and AI. Why complicate it unnecessarily?

I establish a false shoulder and use the COW method only if it is too big of a jump, i.e., from .35 Whelen to .30 Gibbs.

.30 GIBBS fire-forming progress.jpg

From L-R:
1. .35 Whelen virgin brass
2. Established false shoulder with .30 Gibbs sizing die prior to COW method.

.30 Gibbs fire-forming from .35 Whelen - COW method 11g WSF 1 of 2.jpg

(11g of WSF, COW to the shoulder area, and stuffed with a cotton ball).



3. After the COW method.
4. Fire-formed off the chamber with a full load.
 
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bengineer

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Joined
Sep 10, 2011
Messages
88
Location
N WY
I use around 20% case volume of pistol powder below a lee dipper of CoW. Then a measured piece (1/9th for 25-26 calibers)of tp as a wad to hold things together. DO NOT shoot through a brake!!

Fill a case completely with your fast powder of choice. Weigh the powder. Use a fraction of that, working up until you get good fill out. You can also play with the CoW volume and the tp size, both depend on case volume and bore diameter.
 
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Mike Matteson

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Joined
Jun 26, 2017
Messages
1,346
Ackley chambers are designed a bit short in head spacing for a slight interference, just for fire forming.
On firing the body-shoulder junction moves forward to increase shoulder angle. When it does this, it pulls the neck-shoulder junction back a bit, for near perfect form.
You shouldn't need to jam bullets for this.
Depending on how the chamber was set up. A 280AI case to the shoulder is a little longer than most. I am having a 6mm/280AI rifle being built presently. We see how that works. I have been thinking about rechambering my 25/06's to that 280AI size case length, and getting a reamer built for that. I have 500 280AI cases on order from Peterson. When that going to filled, is anybody guess. I have new Lapua and Peterson case new in either 270 and 30/06 on hand. Nosler builds 280AI case, but they want $2. per case, which I feel is out of line.
 

BigDon

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Joined
Oct 2, 2018
Messages
145
Location
Cheyenne, Wy
Depending on how the chamber was set up. A 280AI case to the shoulder is a little longer than most. I am having a 6mm/280AI rifle being built presently. We see how that works. I have been thinking about rechambering my 25/06's to that 280AI size case length, and getting a reamer built for that. I have 500 280AI cases on order from Peterson. When that going to filled, is anybody guess. I have new Lapua and Peterson case new in either 270 and 30/06 on hand. Nosler builds 280AI case, but they want $2. per case, which I feel is out of line.

Why go to all that trouble and expense? Just go with a 25 Sherman and get exactly what you just described!
 
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