Neck Tension

[BruceP]

OK a little help here. How much difference in measurement should there be in the neck of a newly sized case with no bullet seated and the same case with a bullet seated to give proper tension on the bullet. The reason I ask is that I am in the process of forming some 300 whisper cases from 223 cases. I have found that cutting cases at the shoulder and then sizing the case down so I have a proper neck size then trimming to correct length is easer than sizing up the neck from 223 to 30 caliber and it allowed me to size it a little at a time until I had the correct head space for my chamber. I then took two cases and reamed the inside of the neck and sized them again. I measured the necks without a bullet at .3235 and then with a bullet seated I measured them at .325. So would someone with experince at this sort of thing tell me is .0015 enough difference for good tension on the bullet (I am thinking this might not be enough) or should I turn the outside of the necks instead of ream the inside so I could leave the necks a little thicker and give more tension.
This is my first time forming a wildcat case and having to thin the necks so I thank you for any help you can give. Also I know that I can buy pre-formed cases from SSK and I probably will in the future but thought that I should try forming some cases myself just for the experence.
Thanks BruceP

[Cat Whisperer]

Before addressing the question: take this as a starting point for your own rules of thumb.  You should have at least .001" on the diameter clearance between the loaded round neck and the neck of the chamber.  There are those that are much more experienced than I that you should also talk to.  (My experience is based on having a 6ppc with a .264 neck).  With minimum clearance, cleaning becomes important if not critical.  The risk is there not being enough room for the neck to expand.

Back to neck tension.  Consistancy will be more important than amount.  I typically will neck size only half way down the neck to allow the bottom part to align the case in the chamber.  For the same reason I outside neck size to make the case consistanly thick to position the bullet coaxially with the bore.  Inside neck turning is the easy way to bring the case thickness to a correct dimension.

Be safe.

[BruceP]

A little more info for you. Last night before going to work I also happened to think of the size of the chamber neck for release of the bullet so I measured the neck of a case fired in my gun (a TC contender by the way). It measured .335 that gave a clearence of .01 between the chamber and my reamed cases. I then took one of the sized and trimed cases and did nothing except seat a bullet. I measured the neck before seating and then after. It measured .327 before seating the bullet and .330 after. This still leaves .005 clearence for bullet release. If this holds true with all of the cases then it seems that they won't require thinning of any kind. I guess I should have checked all of this first.
Thanks for the all of the replys so far. I would still like to hear further answers from any of you on my question though, it still might come in handy some day.
It might be interesting to prepair some cases both ways and compare accuracy, but to be honest I'm just not good enough with a handgun yet to be able to tell a difference
BruceP