6 Dasher fire-forming loads- Load, Jam, and Shoot (not the false shoulder method)

[Sheldon N]

So I ordered a carbide expander mandrel for my 6 Dasher since that's part of the loading workflow I'm going to use on my Dillon 550. I figured I'd throw in a .257 mandrel into the cart since it was only $10. I had originally planned to jam/shoot with virgin brass but now I'm thinking about false shoulder method.

If I go false shoulder, should I also jam the bullets into the lands as well?

 

[skiutah02]

I've had good luck with this method (below) Fireformed 300 cases this way (most in local matches) and no misfires. A knowledgable shooter told me to use Winchester primers.

Not a Dasher, but should work the same way. But I'm a FTR shooter and only dabble in "weird" calibers so what do I know.

Drew

 

[RenoMD]

I loaded my FF rounds with 30.0gr of Varget, and seated them 50 thou past what I consider in the lands.

Bighorn TL3 action, 25" 7 twist barrel.

105 bthp from Hornady

Brand new barrel gave me 2715 fps.

Shoots great. Can't wait to see what it does with full house dasher loads.

Lapua brass, btw

Can you share what primers you used? Seems like most favor soft primers probably to ensure ignition with little forward movement since the magnum primers have a harder cup and can theoretically move forward a tiny bit when the pin strikes using the jam and shoot method.

 

[upSLIDEdown]

Can you share what primers you used? Seems like most favor soft primers probably to ensure ignition with little forward movement since the magnum primers have a harder cup and can theoretically move forward a tiny bit when the pin strikes using the jam and shoot method.

I just used 450s.

 

[shawnmb]

Are you guys lubing the case at all? And are you experiencing any case shrinkage after fireforming?

Thanks.

 

[Matt P]

Are you guys lubing the case at all? And are you experiencing any case shrinkage after fireforming?

Thanks.

IMO if the case doesn't shrink you're pulling brass from the web area (not good), once again IME forming without the false shoulder has a much greater chance of pulling brass out of the web rather than blowing the shoulder out. The case comes out and looks right, it just hasn't moved the brass from the right area. I tell my customers a good rule of thumb, no mater what method is used you want the case to come out shorter than what it went in.
Matt P

 

[shawnmb]

IMO if the case doesn't shrink you're pulling brass from the web area (not good), once again IME forming without the false shoulder has a much greater chance of pulling brass out of the web rather than blowing the shoulder out. The case comes out and looks right, it just hasn't moved the brass from the right area. I tell my customers a good rule of thumb, no mater what method is used you want the case to come out shorter than what it went in.
Matt P

I agree. Well put.

 

[Alex Wheeler]

I cant endorse the jam method. Bullets can slip. 2 things to check to see if your method is as good as it can be. You want the case to shorten up and you want the oal variation to be similar to virgin cases. If the case is not shortening up your stretching it in the wrong place, why I do not like the cow method. If you have more oal variation than virgin, some are stretching more than others. I like hydro forming best for the dasher. Cases come out about 1.538".

 

[Barlow]

I have had good results from both methods. I do leave a little lube on the case body and find it takes two bangs to perfectly form the shoulder. Barlow

 

[kochie]

Did not want to use my good competition barrel for fire forming. So switched to a well used 6 dasher barrel. Tried the jamming method (as false shoulder method takes extra steps).
Had 50% miss firers. Although the round was jammed in there, with the fire pin strike, the entire case would move forward, and I would end up with a dented primer.
From now on I use the false should method.

was thinking about doing a Dasher but fireforming and all think i will look at another 6 BR variants or 6 GT .

 

[djporter]

6BRX

 

[kochie]

6BRX

ok thanks

 

[Ledd Slinger]

Did not want to use my good competition barrel for fire forming. So switched to a well used 6 dasher barrel. Tried the jamming method (as false shoulder method takes extra steps).
Had 50% miss firers. Although the round was jammed in there, with the fire pin strike, the entire case would move forward, and I would end up with a dented primer.
From now on I use the false should method.

If you know for sure that the bullet was jammed hard into the lands, then it sounds like you have an ignition problem on your action.

Either not enough pin protrusion, weak firing pin spring, badly dragging spring/cocking piece/pin, not enough pin fall, not enough mass on your firing pin…Or a combination of many of those things.

The false shoulder firing method is easy to do and works great, but I would still have a good look at your actions ignition system because I believe you just unveiled a hidden problem while trying to fire form with jammed bullets

 

[L.Sherm]

I'm betting you didn't use enough neck tension and bullet slipped into the neck
when you chambered the round.

 

[Ledd Slinger]

I'm betting you didn't use enough neck tension and bullet slipped into the neck
when you chambered the round.

Possible. If the rim is held up against the bolt face by the jammed bullet and extractor (as was indicated by the fact that the primers had strike marks) it should fire. A good ignition with proper pin protrusion should have a fast enough lock time and energy to fire a primer even if it causes the bullet to slip in the neck as the strike occurs.

I’ve fired many rounds with light jams and .002” neck tension during fire forming in rifles with zero issues. I also shoot 40 S&W in my Glock 20 10mm hand gun. The only thing holding the smaller 40 S&W rounds against the bolt face is the extractor and I have never had a round fail to fire.

Another possibility for the lack of ignition is contaminated or bad lot of primers. I’ve had that happen before