Neck sizing/Neck trimming

[Bigeclipse]

Hey guys,
I am neck sizing some rifles to experiment with accuracy and case lfie. One in particular is a belted magnum. I do not want this thread turning into a "you shouldnt neck size or you should"...etc. Just have a question on overal case length. On my full length resized cases I have always trimmed to between .005 - .010 less than what the book states. For example, if overall max case length is 2.450, then I would trim to at least 2.445. Most time I favor .010 but if it is a rifle that I know they dont move much I dont mind going .005. Anyways, should I do the same thing on neck sized cases or does this become less crucial because they are fire formed to your chamber? The reason I ask is I measured my once shot cases yesterday and after neck resizing they are .003 less than the book max. Should I trim or is it not needed with neck sized brass as long as they are under book value and fit in your chamber?

Thanks!

 

[rsnell]

As long as you are not crimping, you do not need to trim the case until it exceeds the recommended maximum.

 

[MTBULLET]

I trim new brass (after fire form/neck turn/neck size) to .010 under max, but most most important is keep all brass the same length.

 

[Bigeclipse]

I trim new brass (after fire form/neck turn/neck size) to .010 under max, but most most important is keep all brass the same length.

this is what I currently do for my full sizing brass but was unsure about neck sizing. Is there a reason why many people size shorter than max? I would think as long as you re under max it should be okay.

 

[MTBULLET]

if by "size shorter than max" you mean trimming to minimum, i do it because i get more reloads before trimming again.

 

[Bigeclipse]

if by "size shorter than max" you mean trimming to minimum, i do it because i get more reloads before trimming again.

yes I did mean trimming. Thank you for the clarification!

 

[dkhunt14]

Any time you let the brass grow to maximum length you run the chance of really driving pressures up. If you have a little carbon in the neck portion of your chamber and are into it the brass cannot expand and let the bullet go. It is also noted that some guns have shot better with the brass trimmed shorter. It might be because of clean releases of bullets. Matt

 

[Mikecr]

Should I trim or is it not needed with neck sized brass as long as they are under book value and fit in your chamber?

Trimming reqs don't have anything to do with neck sizing, or any 'book max' for that matter.

You trim for an actual chamber end clearance you're comfortable in managing.
Closer the better, but still providing any clearance.
Trim frequency is a matter of cartridge design and sizing amount,, FL sizing amount (not neck sizing amount). So while you're not FL sizing, your actual trim length is not growing. But low shoulder angle/high body taper cases will continue to lengthen over firings, and you will have to bump shoulders back. Each affecting your chamber end clearances as measured.
This is the management I'm talking about, in that you have to closely watch chamber end clearances while you're close.
For some it's not worth the efforts and they'll just trim to excess end clearances and be done with any concern about it.