Dasher Sizing Problem

[BoydAllen]

The setback will depend on how far you have to go, based on a borescope inspection. With that much gone, there may be enough damage down the bore to make a setback impractical.

 

[Sheldon N]

If you have .268 OD for a loaded round and .266 for a sized case at the neck, then you have .002 tension which should be enough. I'm guessing that the 10% of sized cases that won't hold a bullet don't actually measure .266 though.

I would agree with the prior posters that annealing may fix the brass springback and give you more consistent sizing and neck tension.

I don't know if I'd jump to set the barrel back given the simultaneous loose action screws and neck tension issues. Perhaps wait until you've got everything stabilized again and perhaps even do some quick powder charge testing to make sure that your load is still in the accuracy node. If you've got some throat wear maybe you need to tweak seating depth to chase the lands too. If neither of those works and the gun still won't shoot, then you can set it back or rebarrel.

 

[xswanted]

If you have .268 OD for a loaded round and .266 for a sized case at the neck, then you have .002 tension which should be enough. I'm guessing that the 10% of sized cases that won't hold a bullet don't actually measure .266 though.

I would agree with the prior posters that annealing may fix the brass springback and give you more consistent sizing and neck tension.

I don't know if I'd jump to set the barrel back given the simultaneous loose action screws and neck tension issues. Perhaps wait until you've got everything stabilized again and perhaps even do some quick powder charge testing to make sure that your load is still in the accuracy node. If you've got some throat wear maybe you need to tweak seating depth to chase the lands too. If neither of those works and the gun still won't shoot, then you can set it back or rebarrel.

I think this is certainly the best option at this point. There were too many variables right off the bat to jump to a rechamber job. However thanks to the help on this thread I think I will be able to fix the problem.


As far as the tension is concerned I need to use my micrometer (measures hundred thousandths) to see what the cases measure that won't hold a bullet. I agree the .002 tension is enough and this gun has shot some impressive 600 yard groups with that amount of tension. I might even try some new brass before getting too crazy. I'm pretty sure I'll always have a Dasher so more brass can't hurt! Besides I have a 6br and a 22br laying around that could always use more brass.....right?!

Thanks again.

 

[Eric Leonard]

A loaded round measures .271 both turned and unturned.

Wrong......a loaded case measures .268 both turned and unturned

I have a micrometer however I didn't use it today so down to the thousandths is as close as I can get.

When I turned this brass I took very very little off. Just enough to clean up any discrepancies between them. However with lapua brass I don't believe it was necessary. All cases are trimmed, I don't recall the trim length.

if you turned some necks and not others I dont see how they could measure the same as unturned loaded rounds ,,

my .272 neck 6BR I turn all necks to the thinnest side of the thinnest piece,,I wind up with .268 loaded rounds and use .265 bushings and the brass comes out of size die at .2655 and and comes out of the chamber after firing at .271,,

have brass with 25+ firings that still shoot good but I anneal ever 5th cycle,,

 

[Jet]

Think it's time to get a new barrel on order. Once you get it start with fresh brass and enjoy shooting small again. Use your current barrel to fire form new brass.

Good Shooting

Rich