Fire forming brass

[JFrank]

Post #32. I already said I made an incorrect assumption.

I think the horse just twitched if you want to hit it again. Because I'm done. Yes, with you, too.

I thought we were all just chatting around the camp fire ...I’ll apologize for anything I’ve said that may have offended you.
Sincerely

 

[GeoDudeFlorida]

I thought we were all just chatting around the camp fire ...I’ll apologize for anything I’ve said that may have offended you.
Sincerely

No need. My bad. Misinterpreted. Toss another log on the fire.

 

[Chuck R.]

I've used all of the different methods to fireform brass, COW, hydroforming, false shoulder, bullet jam... so I'll offer thoughts here on how and why I would approach this problem:

1) I don't like fireforming in 2019 and beyond, for the simple fact I don't like burning 7-10¢ primers for nothing.

2) I generally prefer to pull up a false shoulder if I have excessive headspace.

3) You do not want minimum or near minimum charges for fireforming. Even CoW method, you'll want high enough internal pressure to truly form the case, otherwise you're stuck with a partial form and more springback than you want.

If I were in your shoes with a long chambered 30-06, I'd pull up a false shoulder, shouldered to a slight interference fit, load with a moderate to upper end load, within the window I'd expect to be loading my actually ammo, and live happy when the brass comes out nearly-perfectly formed.

It's the method I use. Rather than waste any component, I'll just practice while fireforming. Usually the accuracy is very good anyway, can even hunt with them.

Creating a false shoulder is easy and quick.

 

[OFFGRID]

ok whats a false shoulder?

 

[Varminterror]

False shoulders are a bulge in the neck which serves to headspace against the chamber shoulder, created by expanding the neck with an oversized mandrel, then running the brass into the sizing die again to shrink the forward end of the neck sufficiently far enough to allow the case to chamber. This "wedges" the case between the bolt and the chamber shoulder, even through not all of the actual shoulder is supported. So when we fireform, the brass of the shoulder is blown out to fill the space. So for 30-06, needing to add ~8thou to the shoulder to avoid excessive case stretch, I'd anneal, pull up with a ~.323" mandrel, then run it back into the 30-06 FL sizer, setting the sizing die with the Bolt Close Method, sizing back the false shoulder JUST enough to allow the bolt to close.

Comparatively:

• CoW method wastes primers
• Bullet jam method has concerns for pressure, and if your application isn't one where jam is suitable, many folks aren't comfortable with the idea
• Hydroforming requires specialized dies and really begs for a press in an outside shop, or outside, since it's messy

But false shoulder method works with near-normal load data, precision will be nearly the same as the post-fire-formed result, and it doesn't require any special dies to accomplish.

(My preferred "next option" behind false shoulder, in the OP's shoes, would be bullet jam method. Seat the bullets long, jam hard into the lands, and use the bullet in the leade to create that "wedge" between the bolt face and the forward end of the chamber. I'd first prefer to pull a false shoulder to avoid the charge weight considerations of jamming, but my backup plan would be bullet jam. No sense in ordering custom hydroforming dies just to blow 30-06 out to a long chamber. I hate CoW fireforming).

 

[TEXASJD]

I always used about 3 grains of a fast pistol powder, say RedDot. Then fill the rest of the case with cream of wheat, grits etc. up to the top of the shoulder. Insert a wad of toilet paper in neck and compress. Then fire them. Only uses a primer and small amount of fast pistol propellant.

Funny story my uncle when I was a kid would do that to form out his BR brass in the garage at night. (I think 30x47) When he did this he would be yelling like him and my aunt were fighting to mess with the neighbors and my aunt. He would also occasionally leave a live primer for the vacuum and my aunt but I never saw that

 

[CowboyTim]

I used to fireform 8mm Gibbs out of 30-06 brass with a little Red Dot and cases plugged with a little toilet paper. Don't bother anymore, just punch the neck out to 35 and set the shoulder with the Gibbs sizer and go. Of course I don't EVER do this with a compressed load or anything that would be considered "hot".

 

[OFFGRID]

View attachment 1250792

False shoulders are a bulge in the neck which serves to headspace against the chamber shoulder, created by expanding the neck with an oversized mandrel, then running the brass into the sizing die again to shrink the forward end of the neck sufficiently far enough to allow the case to chamber. This "wedges" the case between the bolt and the chamber shoulder, even through not all of the actual shoulder is supported. So when we fireform, the brass of the shoulder is blown out to fill the space. So for 30-06, needing to add ~8thou to the shoulder to avoid excessive case stretch, I'd anneal, pull up with a ~.323" mandrel, then run it back into the 30-06 FL sizer, setting the sizing die with the Bolt Close Method, sizing back the false shoulder JUST enough to allow the bolt to close.

Comparatively:

• CoW method wastes primers
• Bullet jam method has concerns for pressure, and if your application isn't one where jam is suitable, many folks aren't comfortable with the idea
• Hydroforming requires specialized dies and really begs for a press in an outside shop, or outside, since it's messy

But false shoulder method works with near-normal load data, precision will be nearly the same as the post-fire-formed result, and it doesn't require any special dies to accomplish.

(My preferred "next option" behind false shoulder, in the OP's shoes, would be bullet jam method. Seat the bullets long, jam hard into the lands, and use the bullet in the leade to create that "wedge" between the bolt face and the forward end of the chamber. I'd first prefer to pull a false shoulder to avoid the charge weight considerations of jamming, but my backup plan would be bullet jam. No sense in ordering custom hydroforming dies just to blow 30-06 out to a long chamber. I hate CoW fireforming).

thats above my pay grade

 

[Varminterror]

thats above my pay grade

Nah, super easy stuff. You expand brass every time you size, just have to do it as a separate, intentional step.