Checking neck to shoulder thickness

[AussieShooter]

I neck turned a large batch of brass I mislabelled thinking the batches oal was trimmed.
I am now in the position of having neckturned the brass needing to trim to recomended length.
I am concerned I may have cut to deep into the shoulder.
Is there a way of checking the wall thickness at the join?
Do I need to ditch the 300 rounds of lapua brass or should I use them?
If I use them and the neck separates will it damage the chamber/ barrel or is a safety hazard?
What is recomended I do?

 

[former naval person]

Section one of the cases and measure/eyeball it. If really thin at the termination of the neck shoulder junction...toss them. Or be prepared to examine each one you fire and see where the detached neck is residing. It is possible that it can detach and stick in the bore, with subsequent bullets ironing it into the bore. Ruins your rifle and possibly your day/eye.

 

[AussieShooter]

Ok.
Thanks for that. My wallet is about to get a whole lot lighter.