Assuming im using my 270 cases in 1 rifle only, is it safe to do as im currently doing:
Using a Full length sizing die, i back it out so that only about 2/3 of the case neck is sized. I find no problems at all, my rifle shoots great and cases seem to last a long time.
In doing this, when my press's shell holder is in the all the way up position, it obviously doesnt contact the die. This i have read is a no no??? Why?
Can someone please explain if this is leading to anything dangerous....i cant for the life of me work out why it would be not recommended!
My rounds all chamber perfectly and the 270 win case has a long enough neck to support the projectile.

You shouldn't have a problem for several reloads. However, the brass doesn't spring back completely and you'll have to full length resize sooner or later. Check the first two cases in your rifle each time you reload a batch so you don't get stuck with a batch you can't chamber.

Full length resizing, with the die down hard on the shell holder is best if the batch will be shot in more than one rifle, or if it's been fired in another rifle than the one your reloading for.

Bye
Jack

What you're doing is a great reloading practice. The unsized portion of the neck is helping align the case in the chamber for good accuracy and headspacing.

As mentioned, in time and how hot you load, the cases will grow, making chambering difficult. A full length resize and trim will then be necessary.

Always resize the necks to get at least 2/3 of a caliber diameter for proper tensioning on the bullet. My practice is to size down for at least a whole caliber if possible. Some short necks negate this, so I get as much as possible while still leaving a 1/16ths or so unsized. Your .270 cases have lots of neck to them, so this shouldn't be a problem.

Personally, I feel that you need to be sizing the entire neck, stopping just short of touching the shoulder and while using a FL die backed off is ok, an honest neck die is better. The case body then will not be touched and will serve to perfecty center the bullet in the chamber, using the entire body for allignment, and you no longer need a portion of the neck not being sized to do that. I am from the old school that believes you need at least a full bullet diameter of neck holding the bullet, and more is always better; that is one reason I do not care at all for all the short-necked rounds that have become popular of late. Like a woman, a nice long neck is a good thing! Since the neck of the .270 is .383 long, 2/3 sizing it is still giving you almost full bullet diameter (.255) you are OK by most most people's standards, but I still like full diameter. Also, by getting a neck die you will make your cases last even longer as none of the body is being sized. As was said though, hang onto your FL die. After a few loading you will need to bump the shoulder back a thousandths or two, and by having two dies you will not need to readjust your die every few loadings. JMO

Flatshooter,
I think that you are doing the right thing.
I do an additional step;I neck size the case all the way.
I do this because I use cast bullets which cannot be forced into an undersized case neck,and need support from the entire neck.
Frank

No need to size the neck any deeper than you are seating the bullet, any deeper is just working the brass unecessarily. I shot bench rest and done the very same sizing as you describe. Far as cases needing to be full length resizing periodically, I never had to. Many of the bench fraternity, use only seating dies as their chambers are made extra tight in the neck, and the seating dies are only finger pressure. When any sizing is done it is done with a case neck turning tool, to cut the neck down when the brass flows forward and can be felt when hand seating the bullets.

Get a Lee collet neck sizer. This sizes down on a mandrel, so doesn't work the brass any more than necessary,( doesn't drag an expander plug back thru an excessivly sized neck area) & doesn't touch the sholder or body at all. Keep your full length die handy, as you'll eventually need to full length resize.