6mm Dasher,Finally Completed)

[Skeeter]

Moderator = I finished working my way up in charge weights last night. Worked up to about 9.0 gr and right around 8.3 I really stopped noticing any difference in shoulder and neck expansion. Although there was a noticeable change and flattening of the shoulder angle between 7.0 and 8.3 gr. Therefore, I'm going to go with the 8.3 gr load for the remaining brass.

Gunamonth = Thanks for the info, So far I'm actually enjoying this part of the process... had I not had time to burn, I probably would have taken your advice and just stopped at 6.5. I did reference my reamer drawings from Dave Kiff and see that there is a noticeable radius on the shoulder to neck union, but does not appear to be one where the shoulder starts to form off the body. Also, do you do any annealing of your brass after forming?

A few other items of mention.

1.) My reamer has a chamber length of 1.560, unfired Lapua brass measures 1.558, my newly fire formed brass has a measured length of 1.555 .... why would it be so much shorter than the chamber? I understand there is some snapback after forming, but is this excessive?

2.) My chamber has a neck of .269 and after fire forming it measured .2685 ... so I guess I'm either going to have to neck size each case before reloading, or neck turn the cases down to provide more chamber space for the loaded round.

Any thoughts?

Thanks again everyone for the great advise.

Skeet

 

[Forum Boss]

Very nice photos. Looks like you determined the "just right" charge of Titewad.

During the fire-forming process it's normal for the necks to shorten somewhat, as you are forming shoulder from neck.

FYI, looking at my other PT&G std. 6BR reamer prints, the chamber length was spec'd at 1.570", and my fired brass runs 1.556". Many guys trim to 1.555".

I don't think the extra .004" or so will make a difference in accuracy, but you will get some carbon build-up in that small gap. I bore-scoped my barrel last night and did see some carbon right at the end of the chamber. I can brush most of that out though.

Eventually, your brass may stretch a bit again too.

 

[Skeeter]

Thanks everyone for all the great advice and assistance with my fire forming process. I am loading them all over the next two evenings and will fire them all this weekend. Next I'm onto some load testing and chronography while working up my best loads,I'll be sure to post a new thread covering those results).

Only one last question... should I and when should I anneal the shoulders?

Last photo............ Thanks again.

Editor, I PM'ed you a copy without the tag lines.

Skeeter

 

[AckleyImproved]

Great thread!

I will have 2 Dashers very soon. My current one is 0.265NK, and the new a 0.270NK.

I just formed 50 rounds for the 0.265, and in doing so it is a PITA finding the just right amount to turn the necks too before hand. The next time I will try this method, or may just try it for fun!

Awesome thread!

Cheers
AI

 

[jthyttin]

Quick question on neck turning: if you neck turn 6BR brass to the original neck/shoulder junction before the fireforming, would there be any ill effects?

I think that this excessive neck turning would at least eliminate the doughnut problem completely,since upper part of the shoulder would be as thin as the neck)?

Or is the Dasher brass so stable that there's no measurable brass flow?

I don't have 6BR or Dasher, but I plan on trying the excessive neck turning method to form 260Rem brass from 308 brass, to eliminate any possible doughnut problem,although haven't had any doughnuts yet with 243 brass).