Forming bra brass with full loads??

[gunsandgunsmithing]

IIRC, P.O. Ackley recommended a medium charge(for the parent) of a relatively fast(for the cartridge) powder for fire forming his cartridges. Sounds like very plausible info.

 

[ttfreestyle]

Thanks guys, I will relay that he may wanna back off on the initial fire forming load a bit and may want to form them all with the same charge for consistency. Or since I gotta shoot against him..............hmmmm! Nah I’ll pass this info to him.

 

[shoot4fun]

DJ doesn't list 6bra brass.

I thought we all were going to 6bra because its pull the trigger, bang, and go...

There you go thinking again.

 

[JMayo]

I didn't read MAX load by the op.
One would be foolish to ff at max with any case.
I read a bra load. . The 30's is a common ground for 6mm.
I personally ff with 28 - 30 varget.
My pet load for shooting is 30.6.

I also ff'd with pistol powder and cow ...what a mess...

 

[Dgd6mm]

So is the 6bra fully formed after one firing?

 

[mikeeg02]

So is the 6bra fully formed after one firing?

If I anneal before the first firing, I am confident in mine.

 

[farmerjohn]

If I anneal before the first firing, I am confident in mine.

Just to be sure I understand, you anneal new brass before you fire form it?
Farmer

 

[mikeeg02]

Just to be sure I understand, you anneal new brass before you fire form it?
Farmer

With my last four sets of match brass yes. Anneal the virgin cases.

 

[DJSBRS]

DJ doesn't list 6bra brass.

I thought we all were going to 6bra because its pull the trigger, bang, and go...

I have hydro formed several thousand 6 BRA Lapua for many customers all over the country.

It is noted on my web page at the top. djsbrass.com

DJ
DJ's Brass Service
205-461-4680

 

[Ledd Slinger]

So heres an interesting little piece of info I just found...

I hydroformed a bunch of Lapua 300 NMI cases and loaded them for fireforming. (35 deg shoulder and .0179" body taper from .200" line to shoulder)

I then loaded 10 pieces of virgin untouched brass to compare against the hydroformed cases after fireforming. The results were quite interesting.

All body and headspacing measurements came out the same, but when measuring to trim cases for uniformity, I found that the hydroformed cases had an overall length .015" shorter on average than the cases fireformed from untouched virgin brass.

Hydroformed prior to fireforming: 2.465" avg. length
Virgin parent cases fireformed: 2.480" avg. length
Quite a big difference!!!

All virgin untouched Lapua 300 Norma cases out of the box measured 2.481" +/-.001"

Has anyone else tested this and noticed the same thing?

 

[mikeeg02]

So heres an interesting little piece of info I just found...

I hydroformed a bunch of Lapua 300 NMI cases and loaded them for fireforming. (35 deg shoulder and .0179" body taper from .200" line to shoulder)

I then loaded 10 pieces of virgin untouched brass to compare against the hydroformed cases after fireforming. The results were quite interesting.

All body and headspacing measurements came out the same, but when measuring to trim cases for uniformity, I found that the hydroformed cases had an overall length .015" shorter on average than the cases fireformed from untouched virgin brass.

Hydroformed prior to fireforming: 2.465" avg. length
Virgin parent cases fireformed: 2.480" avg. length
Quite a big difference!!!

All virgin untouched Lapua 300 Norma cases out of the box measured 2.481" +/-.001"

Has anyone else tested this and noticed the same thing?

The brass has to go somewhere.

260 -> 260 ai loses ~ .020" (I only remember that because mine went from 2.027 to 2.007.

I forget what br->dasher/br-improved loses.

You just have to make sure your chamber is long enough on your reamer for the parent virgin case. Unless you're having someone else form them.

 

[urbanrifleman]

I have hydro formed several thousand 6 BRA Lapua for many customers all over the country.

It is noted on my web page at the top. djsbrass.com

DJ
DJ's Brass Service
205-461-4680

My bad. Did not see the text, just the picture.

 

[Alex Wheeler]

So heres an interesting little piece of info I just found...

I hydroformed a bunch of Lapua 300 NMI cases and loaded them for fireforming. (35 deg shoulder and .0179" body taper from .200" line to shoulder)

I then loaded 10 pieces of virgin untouched brass to compare against the hydroformed cases after fireforming. The results were quite interesting.

All body and headspacing measurements came out the same, but when measuring to trim cases for uniformity, I found that the hydroformed cases had an overall length .015" shorter on average than the cases fireformed from untouched virgin brass.

Hydroformed prior to fireforming: 2.465" avg. length
Virgin parent cases fireformed: 2.480" avg. length
Quite a big difference!!!

All virgin untouched Lapua 300 Norma cases out of the box measured 2.481" +/-.001"

Has anyone else tested this and noticed the same thing?

We saw the same thing in the dasher. Its why I always preferred to hydro-form dasher brass. The hydro die will pull the neck down into the shoulder more than fire forming will because the neck expands and grips the chamber. So you end up stretching the brass some to fill the shoulder. The test for me is to measure new cases and fire formed cases. I like to see the same kind of es in oal in new vs formed brass. If formed cases vary more than new ones your forming process could be improved.

 

[Ledd Slinger]

We saw the same thing in the dasher. Its why I always preferred to hydro-form dasher brass. The hydro die will pull the neck down into the shoulder more than fire forming will because the neck expands and grips the chamber. So you end up stretching the brass some to fill the shoulder.

Ok that makes sense. Thanks Alex

 

[farmerjohn]

We saw the same thing in the dasher. Its why I always preferred to hydro-form dasher brass. The hydro die will pull the neck down into the shoulder more than fire forming will because the neck expands and grips the chamber. So you end up stretching the brass some to fill the shoulder. The test for me is to measure new cases and fire formed cases. I like to see the same kind of es in oal in new vs formed brass. If formed cases vary more than new ones your forming process could be improved.

Thanks for that Alex, now I understand why I had so much trouble with case length when I was fighting the dasher brass war. Main reason I went to to the BRA was constant problem with getting all the cases to come out alike. If I had it to do over I would try the hydro route. I'm also beginning to see why my smith chambered my fireform barrel .002 undersize or I should say short, I fire form with a lighter bullet shooting prairie dogs and when reload for the first firing all I do is neck size and have a snug fit. cases all come out even length.

John

 

[gunsandgunsmithing]

We saw the same thing in the dasher. Its why I always preferred to hydro-form dasher brass. The hydro die will pull the neck down into the shoulder more than fire forming will because the neck expands and grips the chamber. So you end up stretching the brass some to fill the shoulder. The test for me is to measure new cases and fire formed cases. I like to see the same kind of es in oal in new vs formed brass. If formed cases vary more than new ones your forming process could be improved.

I prefer the opposite. First, the parent case must chamber. So, I prefer my forming method to produce a formed case nearest the actual chamber length. A properly designed reamer should be minimally longer than the parent. Just my 2 cents, though.

 

[urbanrifleman]

Peterson should have made native Dasher brass instead of 6br.

 

[Alex Wheeler]

I prefer the opposite. First, the parent case must chamber. So, I prefer my forming method to produce a formed case nearest the actual chamber length. A properly designed reamer should be minimally longer than the parent. Just my 2 cents, though.

And many guys agree with you. I remember everyone trying to form long dasher brass. I dont like to stretch the brass, or let necks get anywhere close to the end of the chamber. I shortened up chamber lengths at one time, didn't like what I saw, now Im back to giving them room. We have all seen things that form our opinions. To each his own.

 

[Ledd Slinger]

I tried playing it close to full neck length on a couple chambers using varmint rifles. Blew a few case mouths out into the end of the chamber with freshly annealed brass. Pressure spikes and hard extractions. Not good. I stay away from the end of the chamber neck now.

 

[gunsandgunsmithing]

I tried playing it close to full neck length on a couple chambers using varmint rifles. Blew a few case mouths out into the end of the chamber with freshly annealed brass. Pressure spikes and hard extractions. Not good. I stay away from the end of the chamber neck now.

I still trim to .010 less than actual chamber length. Not sure of any voodoo that may have caused your experience. Clearance is clearance and you either have it or ya don't. Or at least I would think so, when it comes to length. I've just never experienced what you describe. I will say that you can't trust a reamer print to be precise in terms of actual length dimensions.