6mm Dasher - Case OAL

[BigDaddie]

Hi All,

can anyone tell me what the CASE OAL for the Dasher should be?

I have just fireformed some new 6BR lapua using the false shoulder. My OAL's are running between 1.5314' to 1.5354'

I have some other brass that I fireformed and shot maybe 3 times after that is running at 1.5433' to 1.5472'

I'd like to make the whole lot uniform as the necks are within 0.001' of eachother.

BTW, the reamer is a PTG 272 neck

Any help would be much appreciated.

 

[alf]

1.555'

 

[AlanPF]

The case diagram on 6mmbr.com says 1.558. With my method of fire-forming,expand to .257 then make a false shoulder with 6mmbr neck sizer)it is usually much shorter, between about 1.530 and 1.545. Seems your method is giving similar results BigDaddie. Has anyone used a method of fire-forming that will give case length > 1.55?

Alan

 

[alf]

With 1.555' being max length, 1.545 is the trim to length.

Your fireform length is normal. Generally if you keep the fireform loads on the stout side, they'll keep to the longer dimension. Most, but not all.

 

[BigDaddie]

Thanks for the replies thus far.

My method was to expand to 6.5 on the mandrel, then size with the bushing die...adjusting until they just chamber on the 6.5 shoulder.

I suppose I can just keep firing them until they grow some more. But the concern is that I'll have all these cases with different neck lengths,ie between the 2 batches I have).

Any other suggestions would be appreciated.

 

[BigDaddie]

I decided to trim the brass yesterday to a length of 1.535',39mm). There were 4 cases that were under this measurement by a very small amount. I'm confident they'll come into measurement after a couple of firings as sighters.

Does anyone see any potential issues with this? I'm not to sure on the pro and cons of being a little short in the neck measurements so any enlightenment will be educational for me!

 

[memilanuk]

I formed my cases the same way... came out with a finished length of around 1.539-1.540. I set my trimmer to 1.538 which got all but a couple - I figure after a firing or two I'll trim them again and see if they have evened out a bit. So far the gun seems to shoot pretty well regardless.