Sizing new brass

[Webster]

Because I don't want case necks pinched between the bullet and the rifling.

I think the necks are a long way from touching the rifling. Look at a blueprint.

 

[Richard Jones]

And a bore scope will tell you if your cases need trimming.....

 

[Eraser]

Always FL size new brass

Why?
You're suggesting to "always FL size new brass." That is what the OP did now he asking what went wrong,
"everything is out of spec." The OP is obviously new, and you're suggesting to him and other new guys to "always FL resize new brass" without explaining the proper procedure that will not make the brass oversized.
I agree what has already been posted here. New brass needs no resizing and usually just some neck unfirming.

 

[Dusty Stevens]

Why?

So they will all fit and not have any surprises

 

[Eraser]

So they will all fit and not have any surprises

Oh, okay.

 

[Webster]

I think the necks are a long way from touching the rifling. Look at a blueprint.

Added Later:
I added and forgot to post. Here goes again shortened up. Take a bullet seated in a case that is seated to touch. The location on the ogive that the the rifling touches to the case neck end is the space between the rifling and the case neck end. That distance on my 6BR with a bullet seated to near touch is over 0.100".

 

[SRP Shooter 1]

Thanks to all for your response.
Dusty Stevens I will agree. The more uniform you start with makes the ammo better

KS

 

[SRP Shooter 1]

Sir Eraser, I am actually not new. I have been reloading since 1970 and was merely seeking opinions in my original post. As I am not opposed to new ideas, although some say I am narrow minded , I do accept
new concepts "SOMETIMES"

KS

 

[nakneker]

I always full length size new brass and set neck tension with a mandrel. I also check the length to see how uniform it is, if it’s wonky I trim.

 

[Murray Brook]

Anyone wanting to know their chamber length Sinclair sell chamber gages that are inexpensive and work well.

Sinclair Chamber Length Gage | Brownells

The Sinclair Chamber Length Gauges are designed so the handloader can determine the true length of his rifle's chamber when measuring from the bolt face to the end of the chamber's neck. This measurement will tell you how much excess case length y...

www.brownells.com

 

[big5ifty]

I think the necks are a long way from touching the rifling. Look at a blueprint.

Looking at a blueprint is not not the same as looking at the brass you're working with.

 

[justinp61]

I have finally started gauging my "actual" chamber length, with a home made gauge of my own concoction. Most chambers are indeed much longer than listed "trim length". I put this data in the die box, and trim accordingly. jd

I did the same thing.

 

[jds holler]

Another one of my theories, which are sometimes "hair-brained" is that if you don't trim too short, you might not get that carbon ring. jd

 

[Bill K]

I usually will run new brass, no matter the brand through a FL die to make sure the neck is prepped, as any of them can have the neck out of round due to handling, etc.
Then I check length and trim, if necessary, chamfer neck then reload them. I just like to make sure that they are all as close as possible to being prepped correctly, in my mind.

 

[Doom]

Cases that has been packaged in a box like Lapua probably will not need sizing. Cases that age bagged like Winchester may well have been tossed around and are much more likely to have deformed necks. I have resized those both FLS and neck sized. Don't use anything but Lapua now. The key to me was to either do nothing or do all the piece in that lot..