Re: Optimal neck tension for hunting
This is how most people express it - in my understanding.
You can measure the loaded round (OD). The amount by which the sized case is less than that (OD) is the "tension". You need to measure to determine how much you are geting; IMHO measuring is what relaoding is about, otherwise we are just feeling around in the dark. Having baselines on things helps you get back to the root cause when things suddenly all go to pieces and you wondered what the hang changed?! A bit of measuring can help you. (My bad habit is to try changing two variables at once! That doesn't help much.). So while one can guess how much springback you'll get, say 1 thou etc., you really need to measure it to know. And as brass hardens over time that will change too.
To achieve the desired tension you can use appropriately sized bushings (in a bushing die) or have sizing dies honed to the correct internal dimensions. Yes, neck wall thickness does influence this as it is the internal dimension that determines neck tension finally. If you have die with an expander that passes through the inside of the neck last, then that determines the ID diemsnion. In that case neck wall thickness does not determine tension. (Although I still think it may have an effect on release of the bullet, but I've no experience with which to back that up).
The thing is that as the necks harden as they are worked and springback changes, the bushings that got you X tension before will now get you Y. Annealing helps with this (although I still need to learn enough to say that I've got it fully worked out).
That said, I haven't experimented with neck tensions. I 've loaded as little as 2 thou and as much as 4thou in my 300 WM and a few in between, all with good results.
I've certainly found anything that finally sizes from the inside to be more consistent - why? Probably because the neck wall thickness is then less of an issue. I've turned necks and sized with bushing dies with success too.
My results are currently as good as the best they've ever been and I'm using a Lee Collett die. I have done a very slight neck turn as well. It's not even 50%, I just touched off the high spots on the necks, which are sorted WW.
I'm sure their are guys with way more experience and knowledge who will chip in and there are lots of previous posts (which is where I got started).
Last edited by LRHWAL; 05-26-2009 at 01:31 AM.
Reason: Added some detail