The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Factory ammo is built to standard spec...why would there be a problem?

Once fired it takes on the shape of the chamber it was fired in. Basically, a full length re-size attempts to return the case back to spec. A neck sizer attempts to get the case when loaded, back into the last chamber that fired it.

Brass lasts a bit longer when not continually full length re-sized and neck sizing is easier.

I know someone who will be on if I have over simplified.

Cherokee wrote:Thanks both for your comments. One more question:

If you use factory ammunition, could you not experience a similar problem?

Factory ammunition is produced within tolerances which correspond to equivalent chamber dimension tolerances, so that any particular maximum cartridge dimension is functional and safe in the corresponding minimum chamber dimension, and vice versa.

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Factory ammunition is sized down to smallest specificaton so that it will fit any gun of that chambering. That is why handloading gives better accuracy as you are tailoring your load to the dimensions and needs of your specific gun. When you fire a factory round the case expands to fit your chamber and the brass shrinks back enough for the case to be extracted. Full length resizing takes the cse back to factory specs and you loose that better fit, hence the neck sizing recommendation.

I am huge fan of the Lee collet dies and think they are the best neck sizing dies on the market bar none, the do need fettling to get them to work properly and they are a bit harder on the brass than the bushing type dies so the cases need annealing more frequently but the mandrel means that it is very easy to control inside neck diameter and therefore bullet tension.