Ackley improved fireforming procedures...

K

kolineman

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Quick question for anyone who does a lot of fire forming of Ackley Imp. cartridges...

Do you guys think its a good idea to put the bullet into the lands maybe .005 or so, or at least touching for proper fire forming?

In the past I have just used factory stuff and just shot, which shot well btw, but looking now to start with virgin brass and reload from there.

This is for a 220 Swift Improved. Will be loading stout (near max) 220 swift loads that have shown good accuracy in the past in other barrels.

I just want to have as well formed brass as possible, with hopefully decent accuracy (I will be hunting with the fire forming loads hopefully) to work with after fire forming.
 
If you're gonna fire a fully loaded cartridge, I don't think it matters much where the bullet is. Just be careful that you don't put too much powder. I don't know the specifics of what your doing there so if the case you're starting with is pretty close to the end result you can do it in one firing. Be certain that the case neck clearance is adequate. I'm assuming it is as you didn't mention it...but check to make sure.
 
Thank you..

I'm running about .003 clearance on my necks...

I just know pushing the bullet into the lands can increase pressure as opposed to jumping them a touch..

Just didn't know if there was some overall standard practice most people use. I have done quite a bit of online research, seems people are split on rather touching the lands with the bullet during fireforming or starting .025 or so off of them.

Thanks again.
 
Here is the procedure I use:
Set shoulder back .005ish (off of chamber dimensions - not the virgin brass. Many times the virgin brass is already set back far enough) .025ish jam. .003+ neck tension. Medium/Stout load. You do not need a maximum load for fireforming.
Apply a super thin coat of oil on brass. I spay Rem Oil on a rag and gently roll loaded rounds over the rag. This will keep the brass from "sticking" to the chamber walls.

The reason for the +.025ish jam and decent neck tension is that when you chamber the round you want the brass to sit tight against the bolt and not be allowed to move forward until the explosion.

As with most things - if in doubt - just do one case and see if it turns out the way you like. Or (better yet)...fireform 2 cases the same way and see if they turn out the same. There are many ways to skin a cat on this one, but (I believe) you only get one chance to make good brass.

Stanley
 
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One reason shooters want bullets touching the lands when fireforming is an effort to keep the case head firmly against the bolt face when the firing pin strikes the primer. That way, the case has a better chance of forming properly forward.

The original design concept of the Ackley Chamber was a shooter could safely fire a factory loaded round in the rifle and out would come a fully formed Ackley Improved Case. With the advent of so many custom reamers, and customized chambers, this proccess can become tedious to someone who is not completely familiar with what is going on.

Appolo's tip of putting lubricant on the case is a good one. Only, I would use sizing wax instead of oil. Oil can flow resulting bubbles on the shoulder.
 
Thank you all...

Thank you all for the info, that's exactly what I needed to know.
 
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