Neck tension

[chief99]

Loading 95 gr. 380 copper plated . Bought 500 once fired brass. Noticed that on some of the brass did not feel right when seating the bullet. Some seating to easy without enough neck tension . Loading mixed headstamps. Upon further inspection realized the Winchester, Federal and Speer had the least neck tension. Loading 25 rounds with these 3 brands and 25 with the with the less known brands , which had more neck tension . The other brands which had much more neck tension was so much more accurate than the 3 well known cases. Does this mean that the Winchester , Federal and Speer brasses are thinner . I think mostly it made me realize how important proper neck tension can effect accuracy. Does this make sense ?

 

[rcmodel]

Yes.

But more probably, you are using Lee dies, and the expander plug is too big, and rough.

Take it out and measure it.
If it measures more then .352", and is rough?

Chuck it in a drill and polish it down until it is just a hard slip fit in a sized case.

You don't want it to expand.
You want it to act a a guide to keep the case centered on it till it reaches the belling portion of the plug.

And you want it slick & smooth.
Not ringed with lathe marks like a bolt thread.

rc

 

[gamestalker]

Do as RC suggested, and if that doesn't solve the problem, try some of the tips below.

How much are you belling? Over belling can significantly diminish neck tension. Only bell enough to prevent issues with seating or shaving.

Over crimping can also diminish neck tension. Under that copper plating is a soft lead core, which gets swagged down when crimping. Only apply enough crimp to remove the slight bell.

Measure the bullets to see if they are under sized.

Generally, Winchester and Speer brass is good quality brass. As to Federal brass, I haven't had much of an issue with it, but now and then I do run into a few bad one's.

GS

 

[Blue68f100]

The majors may be softer not necessarily thinner. If this is the case, repeated use will make it harder. But like already said your expander is too large and needs to be turned down to give proper neck tension.

 

[GLOOB]

IMO, it's highly likely that your sizing die is loose. For one, this is where the biggest variation lies.

Besides that, factory expander plugs are way too small to do this. They're 2 mils under bullet diameter, so they can't even expand a case, let alone reduce neck tension. The Lee 380 expander is quite short and tapered, to boot, and 380 bullets seat relatively deep. So it's simply impossible for the expander to be the problem, even if you are flaring the mouths like trumpets. A factory pistol expander is simply a flare die, which is all you need in most cases, but with the added ability to mildy expand a way undersized case so that it's still too tight for anything but a jacketed bullet.

When you are expanding your cases, feel which ones are loose and set them aside for oversize bullets. Or send the sizing die back and try another.

But if you ever want to try cast bullets, this sizing die will be gold.