Nech Tension question

[johnk]

Because of the lack of elasticity in brass I would wonder if it was possible to get 3 thou neck tension or would the brass just stretch with little extra tightness?

Lee suggests that there is a limit to the amount of neck tension that will actually be applied before the the elastic limit is reached.

John

[Seddo]

i did some measurement this morning:

New Lapua brass 0.331
Loaded new Lapua brass 0.334
Once fired and FL (lee die) sized Lapua brass 0.321

i will see if i can get away with just neck sizing them this time around and order a s type fl die for next time.

[mike H]

Time to try a few other measuring devices.

[DaveMc]

Seddo - have you removed the deprimer/expander mandrel from the Lee FL die? or turned it down?. It should bring you back out to 2-3 thou neck tension even if the die is taking it in too far to start.???

[Seddo]

Dave,

I haven't tried that but its worth a shot just to see what happens. i have another set of lee 308 dies here so i will see what the FL die out of that set does, i bought it just to have the seating die so i dont have to adjust them with different loads.

[Quick]

Dave, I dont think that would work as the bullet will still be the same size so it could create even more tension wouldnt it if the expander mandrel was smaller??

[DaveMc]

Sorry - my question wasn't to try it but rather it sounds like you have the wrong size in there now. My Lee FL die way oversizes but the expander brings it back up to a 334 and a loaded round is 336-337 - The expander should not leave it this undersized.

[David B]

.335 or .336 bushing, new Lap brass is too tight. You will find run out goes out the window if neck tension is to great. Is common practice to expand new Lap .308 brass necks

[XCALIBRE]

Seddo, as Alan said, run up two firings before going into the nitty gritty.
Sometimes it is surprising the variences in new case wall thickness and hardness. Two firings help iron out these variences in neck and shoulder alignment and then give the oppurtunity to give a good account of neck tension that may require brass annealing before going further. Some Lapua batches have a prepondancy to be harder than others and can grip the bullet more tightly, then shoved into a tight chamber can give a good jump in pressure putting the bullet where you don't want it! Once done, refinement
of actual seating pressure and depth can be made consistant.

[Seddo]

Thanks XCALIBRE, I brought home a second set of 308 dies today so we will see what those bring the necks in at. Either way I have decided to load up the 200 cases and have some more fun before having another shot at tuning the load.