Neck turn before or after fire forming?

[DngBat7]

Do I neck turn “skimming/cleanup” before or after first fire forming. The reason I ask is because I noticed the brass grows on average 4 thou in many directions. Shoulder bumps up and out, necks sucks in a little i am guessing. If you turn the neck and “skin the shoulder” I am assuming that all would get changed after firing. So does it make since to wait for the first firing?

 

[Mulligan]

@Dan S
I have done it both ways with my dasher and it doesn’t appear to make a difference in a no turn neck.
CW

 

[mikecr]

You didn't declare the cartridge you're forming, but for standard cartridges turn new cases (before firing), a bit onto neck-shoulder junction, to mitgate donut formation.
PERFECT:

 

[DngBat7]

Sorry. 65cm

 

[DngBat7]

Gotcha. Sounds good. I’ll getrdone then

 

[Mulligan]

You didn't declare the cartridge you're forming, but for standard cartridges turn new cases (before firing), a bit onto neck-shoulder junction, to mitgate donut formation.
PERFECT:
View attachment 1073685

Mike,
I have cut a bit deeper (maybe a lot deeper) into the shoulders of my Lapua 6.5-284 brass that is necked up to straight 284 to mitigate the donut issue. Have you cut further into the shoulder before? if so, what was the results?
CW

 

[GSPV]

I've never seen the value of neck turning in a no-turn neck chamber. If you're able to fire form before turning, it should be a no-turn neck.

With that said, I have a buttload of chambers that are intended for turned necks and I turn prior to first firing in all of them.

 

[dcali]

I just turn it straight out of the box if it doesn't need to be formed in some other way. Never had a problem.

 

[dcali]

I've never seen the value of neck turning in a no-turn neck chamber. If you're able to fire form before turning, it should be a no-turn neck.

With that said, I have a buttload of chambers that are intended for turned necks and I turn prior to first firing in all of them.

I like to skim the necks for no turn chambers because it makes sizing the necks for light neck tension easier - you don't wind up with that oddball case that's plus or minus a thou from the rest.

 

[mikecr]

Have you cut further into the shoulder before? if so, what was the results? CW

I cut about there(just a kiss). It don't have to be exact, but don't dig into the neck-shoulder junction so far as to cause neck separation on firing.

 

[GSPV]

I like to skim the necks for no turn chambers because it makes sizing the necks for light neck tension easier - you don't wind up with that oddball case that's plus or minus a thou from the rest.

If I'm going to turn a neck, I'm going to completely clean it up. If I'm going to do that, I'm going to have a chamber designed for that neck diameter. With that said, I run more neck clearance than most. Especially in a cartridge where I seat the bullets in the lands.

 

[michaeljp65]

If you turn after fireforming wouldn't the carbon in the neck make it harder to get an accurate neck thickness measurement?

 

[Fotheringill]

If you turn after fireforming wouldn't the carbon in the neck make it harder to get an accurate neck thickness measurement?

Yes, in my experience with using a ball micrometer after turning fire formed brass. There is a variance. This weekend, I expect delivery of Lapua .223 brass and carefully turn the same and one of measurements I will be taking will be thickness variances on the inside neck.

 

[Fotheringill]

Joe R-

I have a ball on one side and the flat on the other. It has been suggested I get the ball attachment on the flat side from Amazon for about $17 and it should be more accurate. Saving my milk and cookie money now for the purchase.

 

[Forward543]

Getting into a 6bra. I do not shoot bench. What variation of accuracy should i expect if i dont turn the necks of lapua brass?

 

[Dusty Stevens]

Getting into a 6bra. I do not shoot bench. What variation of accuracy should i expect if i dont turn the necks of lapua brass?

Youll never notice IF your chamber is big enough for a no turn. And youll probably notice itll shoot better fireforming as a 6br

 

[mikecr]

What variation of accuracy should i expect if i dont turn the necks of lapua brass?

You should start a new thread for this, as it's a different matter all together.