I've been shooting up white box Winchester 223 45 grainers ($11.99 a box of 40) and accumilating alot of brass. I've been loading new pre-primed Hirtenberger brass but when I get into the once fired Winchester brass should I full length resize the brass or can I get away with just neck sizing to extend life of brass. Thanks for the input!
Some of you may know, but for those who do not, I have been reloading for more than 30 years. I have been a reloading teacher and authored a number of articles on the subject. I am a pistol instructor as well as a coach for many disciplines within the NRA. This does NOT make me an expert although I have been used as one on more than one occasion. Like you I learn something new every day and hope to do so until the day I meet my maker. Having said that, I would like to offer my opinions:
While it is true that neck sizing is generally thought to extend the life of brass. To be honest there are other factor's that contribute. How hot you load them is tops on that list. Second how is the head space in your chamber. This one leads you back to the neck sizing. Trouble is just because the cartridge you just fired came out of that gun its dosen't necessarily have its exact dimensions. To truly get you brass to the chamber dimensions you need a specific loading process.
Some years back I had a love hate relationship with a 357Herrett cartridge in a T/C contender. If you do not know, this particular cartridge has a reputation for miss fires. As a result of a very small shoulder to head space off of. The fix is to head space off of the rim. The parent case is the 30/30 win, so it has a good rim for this purpose. I needed to be sure I had perfect chamber dimensions. I seated some 200gr rn's out to contact the rifling, added a small powder charge(Wont supply this kind of data) followed by some filler to keep the powder down near the primer. I fired about 50 of these and headed for the loading bench. Next is a starting load. Because the shoulder is still not defined, but enough for good head space. Once there are fired the result is good brass. Now you need to set up your dies to neck size only. I do this with a candle. I "smoke" the neck and shoulder of the case. Run the seizer die out and re-size a case. Remove and close inspect how much you just sized. Ideally you want the shoulder to just "KISS" the inside of the die, but NOT MOVE IT. You now set the lock and the die is set for neck sizing. There is no LEE Collet dies for this caliber.

I do LOVE the LEE collet die and I am NOT a LEE supporter.
Sorry for the longwinded story, but I think it will give you some background into neck sizing.
AS for your question, like Quick, said all guns and chambers are different. Try the neck sizing, only your gun will tell if it will work. Just be sure to use brass from that CHAMBER ONLY.
Quick,
Concerning your 243 woes, Flattened and Craterd primers are generally more pressure related than head space related. Even craterd primers can be different on Handis as the firing pin remains extended as long as your fingers on the trigger. Heck, and oily chamber can do funny things to some loads!!
Primers protruding from the pockets and a light colored ring around the base of the brass are head space signs.
If it where mine, I would do a creosafe cast of your chamber and see what that shows.
Good luck,
CW