6BR-Dasher, trim case to ??

[Gina1]

After fire forming several hundred Lupua 6mm BR Norma cases to 6BR-dasher, I checked the over all case length. (base to top of neck). The drawing of the 6BR dasher shows a max length of 1.560 inches.
The problem I have, in checking the length is I have cases that are from 1.535" to 1.552".
SO.... Asking all of you Dasher shooters out there. What length do I trim all the cases to ??
Much thanks..
Gina

 

[Terry Altom]

For mine, I want the neck as long as possible. With that, there are usually a few that are outside the average, either shorter or longer. You can trim the longer down. I'd say measure, sort into 0.001" groups. If most are above 1.540" for example, then trim to that. You can then trim the remainder of the short ones to 1.535" and use them for foulers.

I was getting a formed length of around 1.545; on my last rifle, but am seeing a consistent 1.538" on my new one.

 

[Jet]

Gina

I trim mine to either 1.542 or 1.540. Both shoot well. I've never been able to get brass formed consistently over 1.548.

Interested to see how the new Norma stuff works out.

Good shooting

Rich

 

[Charles]

I get good length by cutting neck down and fireforming,per johara article. 1.552-1.556.

 

[BenPerfected]

If you get the neck tension correct and consistent, does the length of the neck really matter?
Ben

 

[Alex Wheeler]

Trim to your shortest. Neck length is the last thing I am concerned about. I like the short cases.

 

[racesnake]

Charles....do you have a thread to the johara trim article?

 

[Gina1]

Thank you for all the advice. The majority of the cases, over 80% were under 1.540 (1.539-1.535) a very few were over 1.550. Since I can't trim them longer, I guess my target trim is going to 1.536" and see how they group. (ladder time)...again (powder and seating depth)
Gina

 

[Alex Wheeler]

Thank you for all the advice. The majority of the cases, over 80% were under 1.540 (1.539-1.535) a very few were over 1.550. Since I can't trim them longer, I guess my target trim is going to 1.536" and see how they group. (ladder time)...again (powder and seating depth)
Gina

Your short necks will not hurt accuracy in any way. My hydro brass all forms to 1.539-1.540. It shoots great, and I dont sort it. I highly recommend hydro forming, your brass will be short but extremely consistent in length because it pulls the neck down into the shoulder rather than stretching the case body which seems to be rather inconsistent as your results show.

 

[Terry Altom]

Thank you for all the advice. The majority of the cases, over 80% were under 1.540 (1.539-1.535) a very few were over 1.550. Since I can't trim them longer, I guess my target trim is going to 1.536" and see how they group. (ladder time)...again (powder and seating depth)
Gina

Are you resizing them prior to the measurements you're stating? If not, measure a few, resize them and measure again. I usually gain one or two thousandths after resizing.

 

[4xforfun]

My Dasher brass at the 2011 nationals was 1.500. A MAJOR screw up/brain fart during brass prep on my part was the cause!!!

It did ok!!

Tod

 

[Dubya]

What is a safe chamber length if your Dasher brass is 1.550.
In other words how much longer should the chamber be than the brass?

Gary C.

 

[dkhunt14]

What is a safe chamber length if your Dasher brass is 1.550.
In other words how much longer should the chamber be than the brass?

Gary C.

I always trim .005 to .010 shorter then chamber. You have to what chamber is in the gun. I have seen reamers vary from 1.550 to 1.570. Matt

 

[Brians356]

I would segregate them by blow length, then trim to whatever length you choose. Inconsistent blow length is most likely inconsistent volume thereafter.

What is "blow length"?
-

 

[savagedasher]

Without knowing what reamer lingth who could say . But 5 thousands is safe. Unless you have set the shoulder back. Larry

 

[Brians356]

I'm just referring to the case length after fire forming as "blow length"

Thanks. Are there techniques in fireforming to maximize blow length (or minimize shortening) without incurring other problems?
-

 

[22DASHER]

Thanks. Are there techniques in fireforming to maximize blow length (or minimize shortening) without incurring other problems?
-

Absolutely. Lots of trial and error involved too. That is something you need to experiment with. Some techniques work for me, other techniques work for others, and some people can't get long blow lengths no matter what method they use...

 

[savagedasher]

Absolutely. Lots of trial and error involved too. That is something you need to experiment with. Some techniques work for me, other techniques work for others, and some people can't get long blow lengths no matter what method they use...

Flat base bullets help . Larry

 

[dmoran]

I would segregate them by blow length, then trim to whatever length you choose. Inconsistent blow length is most likely inconsistent volume thereafter.

Tom

^^^ +1
Consistent blow lengths is a must for consistent volume's, in my experience.
Try to keep mine with in 0.004" and cue out the others (I use them for test/waste brass).
Also find the ones that blow short are more "sluggish" to stretch & growth then ones that blow long.
Donovan

 

[savagedasher]

I think you ask what is the trim lingth !
To me that would be dermined by the chamber reamer used when chambering. Case lingth should 5 to 10 thousand short of the reamer spec.
Any thing less then that is safe. Larry