Another Dasher Question

[AR Shooter]

Am setting up to fire-form 200 new Lapua 6mmBR cases in my 6mm Dasher. Am wondering if the cases need additional annealing or is 'from the factory' good enough? Will be using the 'jammed bullet' method to fire-form. Thanks.

 

[ShootDots]

You will be MUCH better served if you anneal first. In the last 200 rounds I fireformed, I lost only 1! Now, it appears to be the case that you are set on the "jam" method... You would be doing yourself a GREAT service if you used the "False Shoulder" method. However, having said that, IF YOU MUST fireform using the jam method, make sure you have 2 bases covered: 1.) make sure you have at least 3K neck tension and 4 would be better; and 2.) jam the bullets to a good jam, 15K-20K would be good.

I think you would also do yourself a favor if you used "about" 29.0-30.0grs of either Varget, H4895 or RL-15.

 

[dkhunt14]

I also hope you have a fireform gun. That's a lot life out of a barrel.

 

[AR Shooter]

I'm good with the false shoulder method, as well (did the same on Grendel brass to get to Turbo40Imp), but was trying to go the 'easy' route. Plan is 30gr of H4895 or Varget. As was suggested, am saving the RE15 for competition.

No problem on the barrel. We shoot a 300yd 'fun' match that is great for fire-forming.

 

[savagedasher]

You will be MUCH better served if you anneal first. In the last 200 rounds I fireformed, I lost only 1! Now, it appears to be the case that you are set on the "jam" method... You would be doing yourself a GREAT service if you used the "False Shoulder" method. However, having said that, IF YOU MUST fireform using the jam method, make sure you have 2 bases covered: 1.) make sure you have at least 3K neck tension and 4 would be better; and 2.) jam the bullets to a good jam, 15K-20K would be good.

I think you would also do yourself a favor if you used "about" 29.0-30.0grs of either Varget, H4895 or RL-15.

4k and 20k or more with flat base bullets works well. You will lose two or less cases per hundred.5k with boat tails works also. Larry

 

[LRPV]

I would recommend using soft primers instead of say 450's too.

 

[rickiesrevenge]

I would recommend using soft primers instead of say 450's too.

Any particular reason?

 

[LRPV]

The softer the primer cup, the less chance of the firing pin moving the case forward before ignition. Guys I shoot with will use softer primers even with false shoulder+ jam.

 

[AKShooter]

I'm is a similar boat as poster......Primers, what would you consider a soft primer? Would stepping back to a regular small rifle be smart, say the CCI BR-4? Have lots of these too, and just one brick of 450's

 

[ShootDots]

ALL CCI rifle primers are pretty hard... A Fed 205 will be a bit softer.

 

[AR Shooter]

I will use Winchester SR primers. Likely the softest primers out there (think slam-fire in ARs).

 

[BradY]

Fire formed a dozen this afternoon myself, 30gr varget, fed 205 and 105 noslers jammed 40 thou without any false shoulder. They formed perfectly. Going to shoot 300m f class this Sunday with it. I have a short 21 inch fireforming barrel that's accurate enough for club use.

 

[Phil]

Fire formed a dozen this afternoon myself, 30gr varget, fed 205 and 105 noslers jammed 40 thou without any false shoulder. They formed perfectly. Going to shoot 300m f class this Sunday with it. I have a short 21 inch fireforming barrel that's accurate enough for club use.

What did you end up getting for a case length????

 

[savagedasher]

Most of the time when you fire form from a 6BR to a dasher the cases shorten. Larry

 

[4xforfun]

+++1 on SHOOTDOTS first post!!!

 

[BradY]

1.544 was the average length of the 12 cases. Supposed to be about standard for blue box brass. I could up the pressure more with more powder to try and get a longer blow length, but its an unbushed remington bolt with fed 205 primers. Dont want to risk too much pressure on an unbushed bolt. The cratering is pretty evident. Also I think this barrel may be fairly tight. I fireformed a gold box of BR cases a while back to use as varmint cases and for a bit of club fun at 300m f class with 107 sierras. After 3 firings with 32.2gr varget and a 107 jumped 20 thou, and a couple with 35gr benchmark and 55 noslers jumped over 100 thou, the primer pockets are quite loose.

 

[Killshot]

I use 30.5gr of Varget, soft Winchester primers and a .035" hard jam with Virginia Lapua brass.

Good blow-lengths, no split necks and accurate enough for short-mid range club matches. All shot in a now-retired Dasher barrel.

The soft primers are key for the Jam method of fireforming.

 

[22BRGUY]

I also hope you have a fireform gun. That's a lot life out of a barrel.

Take your time between shots, maybe 4 or 5 minutes so as not to build up heat.
JMHO