fireforming , trimming 280 Ackley brass

[flatsticks]

Going to fireform regular 280 brass into the chamber of my 280 ackley .

understanding we dont want to max out the powder charge should I just stay with the startng charge ?

The chamber is the original wildcat version so what would a good method be to measure max brass length and arrive at a good trim length after resizing ?

Thanks for your ideas

 

[AJC1]

A max 280 charge will be optimal to fire form the case. You will get less than standard 280 velosity when forming.

 

[JFrank]

I might be a touch more conservative and try one of two at a slightly lower charge than normal, confirm the shoulder formation looks appropriate etc.
I could add powder if needed, are you jamming rounds on a crush fit ?
I’m not sure what the trim length is on your chamber but when I form bra Ackley cases my necks get shorter by a small amount.

 

[troy fairweather]

The necks will get shorter when fireformed, plus you need the full length neck to headspace. Ackley recommended full power loads even max book will be middle power load in the Ackley. These normally get pretty good accuracy when forming.

 

[41 Mag]

With my 3 AI calibers I used factory ammo as a starting point with two and a handload for the other. One is the .223, then a 30-30, both in Contender formats. The last is a 25-06 I had custom made.

With the '06 I used some 100gr bullets, and IMR-4831 with a load 1 grain off an averaged load from several manuals. I seated the bullets to the listed OAL in the manual. No need to jam bullets into the lands.

I set off from the getgo with 200 new cases. All were FL sized and the necks just squared. As mentioned above, they will come out shorter once formed.

After you form up 20 or so cases set 5 aside and use those to work up a max with your choice of powder. Start by measuring the base of the formed cases just above the extraction groove, before you resize them, then after. Note these down in a log. If you don't have one maybe pick up a mic that reads 0.0001. This will help determine case head expansion while you work up. I stopped when I got between .0003 and .0005 over the initial formed case head diameter and I could just see the edges of my primers starting to square off.

Also as mentioned, your max load data for the standard version should be around a 3/4 load, but depending upon the chamber and barrel it could be more so work up slow. I went with a 1-8 twist barrel in order to run heavier for caliber bullets like the Berger and other custom 130gr types. I actually settled on a 120gr CL of all things but found that the old 120gr Nosler Solid Base squeezed a bit more accuracy out so I'm sparingly using them until I run out..

If it were me,, I would likely choose something around the 150gr and a slow powder like H1000 or Ramshot Magnum, or maybe just a touch faster like H4831. I went with the powder that gave the highest listed velocity with the lower listed pressure in order to get all I could from my 28" barrel. I never have seen a need for magnum primers, but did note better accuracy when using the CCI BR2 primer over the Win and Fed I tried.

Good luck and hope you end up with a shooter. While it is improved don't get locked into trying to make it a 7 mag. Look for around 150-200'ish fps over the standard load and go for accuracy first over velocity. Just remember more isn't always better.

Hope that helps

 

[TEXASJD]

AI's will shrink when forming, will need FL sized and fired again to get true shoulder. I normally start at close to max on parent case even fireforming, H4350 and H4831sc work well.

 

[flatsticks]

Appreciate the insights so far.

Was thinking I should get a 7mm sinclar chamber length gauge and see how long the brass actually is stretched all the way out in the chamber ?

Can trim from there I suppose when they get too close to the max length .

I have H4831SC to load them up with and some 150 Hornandy eldx to use to firform the brass .

Hogdon website has load data for280 ackley ( the improved version ) 150gr bullets from 54.1.-57.5

Have some reloads that were made up for the gun by a local guy who had 140 nosler bt in rp brass and 60.0 of h4831, they already have the shoulder on them .

Have the bullet seater depth set up already to mirror the length on the reloads that were made for the gun , did not have it set up to touch the lands .

 

[AJC1]

Jamming the bullets is to hold the case against the bolt to prevent case head seperation. It may not be nessary if your gun is headspaced correctly.

 

[flatsticks]

Jamming the bullets is to hold the case against the bolt to prevent case head seperation. It may not be nessary if your gun is headspaced correctly.

Thanks for that was not aware what that process was for .

 

[Varminterror]

Improved chambers shouldn’t need any fireforming tricks, especially if they were originally reamed as AI chambers, rather than opening a standard chamber (which is why most smiths prefer to set back barrels a turn before improving) - we should have a tight fit at the shoulder/neck junction.

I pull up a false shoulder instead of jamming bullets, especially in AI’s.

I will echo - don’t use starting loads for fireforming. We need good mid-to high pressure loads to form clean shoulders, something in the upper end of standard cartridge, non-AI load data.

 

[AJC1]

Thanks for that was not aware what that process was for .

Before 280ai was standardized some people would have issues trying to fire form, because the ai shoulder was not in the proper place to hold the case, and many people had problems. Another good way to prevent the same problem is with a false shoulder. It requires an expander that you might not have on hand. Both solutions are effective at preventing excessive stretch near the base, and some are uncomfortable jamming. I like having options.

 

[AJC1]

Improved chambers shouldn’t need any fireforming tricks, especially if they were originally reamed as AI chambers, rather than opening a standard chamber (which is why most smiths prefer to set back barrels a turn before improving) - we should have a tight fit at the shoulder/neck junction.

I pull up a false shoulder instead of jamming bullets, especially in AI’s.

I will echo - don’t use starting loads for fireforming. We need good mid-to high pressure loads to form clean shoulders, something in the upper end of standard cartridge, non-AI load data.

Ha ha we were both typing the same advice

 

[flatsticks]

Thanks for clearing up the reason people were jamming the bullet in.

Checked out the non AI 280 rem load data on Hogdon and for 150 bullet and it is 50-53.7 , as expected lower than the 54.1.-57.5, for the 280 AI data .

 

[Nature Boy]

One of the nice benefits of an AI is not needing to trim after you’ve established the new dimensions.

I assume the 280 AI is the same

 

[AJC1]

One of the nice benefits of an AI is not needing to trim after you’ve established the new dimensions.

I assume the 280 AI is the same

I'd say you may be lucky to trim ever if your die and chamber are close... I expect a lot of shrinkage on fire forming.

 

[Nature Boy]

I'd say you may be lucky to trim ever if your die and chamber are close... I expect a lot of shrinkage on fire forming.

My 6 BRA brass hasn’t grown any since fire forming.