6 dasher fire-forming, false shoulder, step by step

[TackDriv3r]

I prefer a hard jam over the false shoulder, or cow. False shoulder method cases come out shorter than the other 2 methods and its more time comsuming. I just load them and Fire form on gophers. No wasted components and happy birds.

How much of a jam are you using? I have 200 pieces of Lapua 6 BR brass to fireform to 6 Dasher, but they are 1 X fired. I don't want to use the false shoulder method.

What charge of Varget is a reasonable amount to use? It may take about 2 firings to form to Dasher.

 

[Ackman]

I don't have a dasher, but do have a couple 6BRX, essentially the same thing. Forming.....expand to .25 cal and neck back down to 6mm. Not a big shoulder but you can definitely feel it. Forming loads are so accurate I couldn't believe it. But in your case, just buy Alpha 6 dsher brass and be done with it. It's good stuff, really.

 

[TackDriv3r]

I don't have a dasher, but do have a couple 6BRX, essentially the same thing. Forming.....expand to .25 cal and neck back down to 6mm. Not a big shoulder but you can definitely feel it. Forming loads are so accurate I couldn't believe it. But in your case, just buy Alpha 6 dsher brass and be done with it. It's good stuff, really.

I'm having issues with Alpha brass in a Alpha reamed 275 no turn chamber, no carbon on the shoulders on virgin brass when fired, but heavy carbon on the shoulders on 1 X fired brass with .002 bump, its why I wanted to try Lapua. Using a Alpha SAC full size bushing die as well. I did everything possible to find out what the issue is with the heavy carbon.

 

[Ackman]

I'm having issues with Alpha brass in a Alpha reamed 275 no turn chamber, no carbon on the shoulders on virgin brass when fired, but heavy carbon on the shoulders on 1 X fired brass with .002 bump, its why I wanted to try Lapua. Using a Alpha SAC full size bushing die as well. I did everything possible to find out what the issue is with the heavy carbon.

It sounds kinda strange, that the Alpha reamer would have a .275 neck. I'll be using Alpha 6 dasher brass to form some 6brx cases and see how that works.....just ran it througn the brx FL die to squeeze the shoulder and upper case body a little. Anyway, those loaded dasher cases are all .268 just like their 6BRA, same as Lapua. I can't imagine why their reamer would have a .275 nk. I think that's part of your problem. And do fired cases chamber fine? If so, why bump?

 

[FeMan]

.....do fired cases chamber fine? If so, why bump?

In the Dasher, I stopped trying to measure the shoulder bump on brass in the first few firings as it didn't seem to correlate to clean-close like in other cartridges. I just try the Dasher brass sized with no bump in the chamber and keep inching down until I get a clean close. After three of four firings it seems to stabilize.

In my experience, I would lose 3% to 5% of the cases to splits fire forming Lapua 6BR to Dasher brass without the false shoulder. With the false shoulder, I really dont lose any.

 

[TackDriv3r]

It sounds kinda strange, that the Alpha reamer would have a .275 neck. I'll be using Alpha 6 dasher brass to form some 6brx cases and see how that works.....just ran it througn the brx FL die to squeeze the shoulder and upper case body a little. Anyway, those loaded dasher cases are all .268 just like their 6BRA, same as Lapua. I can't imagine why their reamer would have a .275 nk. I think that's part of your problem. And do fired cases chamber fine? If so, why bump?

The fired cases headspace was measured at 1.193", and I tried to chamber those fired cases and it was so tight, so I bumped to 1.192", and checked bolt resistance, just little resistance, then bumped another thou to 1.191" and its perfect there. It stumps me on why the chamber is a 275 no turn, as the gunsmith stated after he sent me the rifle. The loaded round neck is indeed a .268 with Alpha and Lapua brass.
A friend loaned me 4 cases of fired Lapua Dasher brass, and I cleaned them up and sized them, and need to go out and test them.

 

[William Vogel]

It sounds kinda strange, that the Alpha reamer would have a .275 neck. I'll be using Alpha 6 dasher brass to form some 6brx cases and see how that works.....just ran it througn the brx FL die to squeeze the shoulder and upper case body a little. Anyway, those loaded dasher cases are all .268 just like their 6BRA, same as Lapua. I can't imagine why their reamer would have a .275 nk. I think that's part of your problem. And do fired cases chamber fine? If so, why bump?

I thought it was 0.272 nk. I’m pretty sure that’s what mine are.

 

[TackDriv3r]

Tried Lapua brass today, still the same issues as the Alpha

 

[shoot4fun]

How much of a jam are you using? I have 200 pieces of Lapua 6 BR brass to fireform to 6 Dasher, but they are 1 X fired. I don't want to use the false shoulder method.

What charge of Varget is a reasonable amount to use? It may take about 2 firings to form to Dasher.

The use of OFB Lapua 6BR to fire form to Dasher is not ideal. As far a having a .275 neck, I would measure the necks on a few pieces of the Alpha you have fired and not yet resized. If your reamer is a .275 that brass should measure (depending on spring back) .273 at the low and .274 or .275 at the largest.
I have Lapua Dasher brass for one .271 chamber that I found shoots best at a .266 loaded diameter but that is unusual. One usually wants .003-.004 clearance.
Having what is likely .008 neck clearance is more than likely the cause of your sooting neck/shoulder.

 

[TackDriv3r]

The use of OFB Lapua 6BR to fire form to Dasher is not ideal. As far a having a .275 neck, I would measure the necks on a few pieces of the Alpha you have fired and not yet resized. If your reamer is a .275 that brass should measure (depending on spring back) .273 at the low and .274 or .275 at the largest.
I have Lapua Dasher brass for one .271 chamber that I found shoots best at a .266 loaded diameter but that is unusual. One usually wants .003-.004 clearance.
Having what is likely .008 neck clearance is more than likely the cause of your sooting neck/shoulder.

I did measure the fired Alpha brass and it measures .274 at the neck.

Loaded round is a .268, so .272 should be the right size.
I'm going to have that chamber set back to use .272 I'm done messing with it