Neck sizing / turning process

[JCSC]

Can someone clarify the process and reasoning for the various mandrel sizes in the step.

The hornady hand turn took for instance, has a .2615 mandrel for 6.5mm, yet sinclair sells .262 turning and .263 expanding dies.

in understand in the final neck sizing operation, that I will want a mandrel in the die that gives me .002/.003 tension, but why use the way undersize die during turning.

I want to get in to this for 6.5 on a budget. Really just something to keep me busy in stead of burning ammo. I also have a bunch of 308 brass that I could convert and neck turn if I had the proper set up.

 

[Blue68f100]

The size will depend on your brass wall thickness. Then you have to allow for spring back. And spring back is different if your annealing your brass.

Measure your finished round, get several reading on several samples. Then pick a mandrel that will give you what you shooting for.

btw. I never end up with just 1.

 

[243winxb]

Hornady is using fl sized brass coming from a standard die that uses an expander. The turning mandrel needs to be small enough to fit in the sized neck, of all brands of brass. As said above.

Sinclairs 263 is just a standard expander allowing a snug fit for the 262 turning mandrel.

The distance between the cutter & mandrell is what sets neck wall thickness. Think of it as a pinch point. The mandrel diameter just has to be close.

 

[JCSC]

Thanks. That makes sense.

 

[NMexJim]

Neck tension comes as a result of the interference fit between the ID of the sized case and the OD of the bullet. Generally, .002 or .003 is considered a good fit between the two, but some shooting disciplines may differ.

When you say "hand turn", I'm going to assume you're neck turning your cases to get an even thickness around the case rim. Personally, I avoid neck turning by buying brass that comes with concentric necks such as LaPua or Hornady, depending on what I'm doing.

So, a mandrel in a neck turning device results only in a snug fit into a sized case neck to eliminate any slack that might affect achieving good concentricity when trimming.

But, expanding, or whatever method you use to size your case necks, gets to be a whole 'nuther beast. Rather than go into it all here, I would direct you to visit YouTube for a quick learn. Go to Gunwerks and look at their video Neck Tension While Reloading. Most reloading manuals have sections on it as well. Accurateshooter.com has a couple of articles: "Neck Tension - Not Just Bushing Size" and another "Expander Mandrels and Neck Tension". Varmint Al's page under mini-lathe has a neck turning section you might like as well. Hope this helps.

 

[JCSC]

Thanks Jim.