Neck tension

[JCSC]

I use a small base sizing for with expander ball.

[Klem]

JC,

Is your chamber tighter than SAAMI? Just wondering why the small base die.

(I use a Forster sizing die without the expander ball. It gives ,004" of neck tension whereas if I left the ball on it gives only .001". Playing around with the die I just got lucky. Doing the same to a Redding still only imparts .001". I figure sizing the outside of the neck is enough to make it concentric and the bullet acts a mandrel when seating).

[Kswhitetails]

Klem, I've found the same exact things you list here. You are correct, the bullet does act as a mandrel, but they are much softer than a mandrel. I haven't gone the mandrel route yet, that's next. I'd expect that the mandrel would be more consistent, but wonder if it's actually worth the extra step considering I load for auto loaders. Time and testing will tell, but in reality it's a fifty dollar test.

[JCSC]

Klem

The LBC 264 SB die is just what happened to be available and it’s what I use on my 556 AR ammo.

[centerfire]

Klem, I've found the same exact things you list here. You are correct, the bullet does act as a mandrel, but they are much softer than a mandrel. I haven't gone the mandrel route yet, that's next. I'd expect that the mandrel would be more consistent, but wonder if it's actually worth the extra step considering I load for auto loaders. Time and testing will tell, but in reality it's a fifty dollar test.

It is worth it. I switched to a Porter Machine mandrel and I can use any conceivable size mandrel down to .0002. In other words, you can neck size for gas guns as well as bolt guns and choose any size mandrel you want. I run .002" of interference for bolt actions and .0032" of interference for gas guns. I anneal every firing and the brass comes out identical with +/-.0005 of runout at the case mouth.

[Klem]

Ks,

I don't think it is as simple as saying one metal is softer than the other and therefore the softer metal will be pushed around by the harder metal. Surely there are other factors and forces at play here.

My Grendel cases have been sized by a die without the expander ball. The neck has been sized from the outside only. For hard metal pushing around soft metal to be of concern the neck must not be concentric. Because if the neck is perfectly round then hard metal is pushing soft metal equally in a perfect circle and everything is fine. But let's say the neck was badly dinged on one side by the deflector on ejection and you went straight into seating the next bullet (unusual hypothetical I know). Seating might also be down to the elasticity of the neck vs. the incompressibility of a solid cylinder. The 'give' in the cupronickel jacket reinforced by solid lead tamping vs. the malleability of brass with no external tamping.

Regardless, when I first removed the ball I measured the outside of the neck with micrometer to see how concentric the neck ended up. Turning the case a few degrees at a time in a full circle and realised that it was concentric...You don't need to size the inside as well. This now allays any concern that the case is going to deform the bullet unevenly as it goes in. The results on the target which is the acid test also tell me nothing has degraded.

As for using the bullet as a 'mandrel', every time we seat a bullet it is by definition a mandrel. With, or without the expander ball a bullet going into a sized neck acts as a mandrel to expand it slightly. For without being a mandrel it will not be held by the neck.

Centrefire's method of using proper mandrels is the precise way of doing it but my 'poor man's version works for me. If it was for a bolt gun in Bench Rest competition then sure, all options are on the table.

[Mad Charlie]

It is worth it. I switched to a Porter Machine mandrel and I can use any conceivable size mandrel down to .0002. In other words, you can neck size for gas guns as well as bolt guns and choose any size mandrel you want. I run .002" of interference for bolt actions and .0032" of interference for gas guns. I anneal every firing and the brass comes out identical with +/-.0005 of runout at the case mouth.

I don't think that you can really go wrong using a mandrel. I use Imperial graphite inside the necks.

[centerfire]

I don't think that you can really go wrong using a mandrel. I use Imperial graphite inside the necks.

I've been using a Sinclair for years but switched to Porter because of mandrel size availability.

I've used graphite before but still had brass galling on the mandrel. I've gone back and forth and it comes back to how much brass I'm sizing. Tonight I loaded 25 rounds of 223 and used sizing wax on a qtip. Large batches I use lanolin. Wet lubrication feels a lot better than dry from a pressure standpoint.