I have read some post stating that I can neck size with a full sizing die. My question is how do I decap the primer when resizing just the neck (with a full length die). Do I have to buy the " specific neck sizing die" ?? Any help is appreciated.

I may be wrong and although i' ve never neck sized with a full length die I think it can be done but i don' t think the full length die will decap the case because it won' t be screwed down far enough. I think it would be better to buy a neck sizing die.

There are only a few thousandths of an inch between full length and neck sizing in regards to setting the depth of the die. The decapping pin will still stick out the bottom of the case.

[Deleted by Admins]

Thanks for your replies but am still wondering.... If I don' t have a neck sizing die and don' t have a decapping die, I just have a full length die. Can I neck size a bottleneck cartridge and decap it with a full length die???

Yes you can ! It takes some adjusting of the die and the decapper !
If you have Hornady dies or Lee,it is a pain in the neck,to adjust them ,because of the pinch nut that holds the decapper pin .
On others,un-screw the decapper,up to where it is away from knocking out the primer. Next,adjust the die body down to the amount you wish to size the case neck ? I use to use graphite on the neck,as a way to see just how far down I had come.Then,once set up,re-adjust the decapper pin,to knock out the primer .