Home Forums Reloading Big Game Rifles Sinclair Case Neck Expander Die and Mandrels

I just ordered their Gen II expander dies and some mandrels.

If you are using madrels for neck expansion, are you getting better results regarding runout than if you used an expander ball?

I plan on using a touch of imperial in the necks before running them.

Thanks.

I found they sometimes add to the concentricity issue.....

Interesting. Any thoughts on why that might be?

Might have been due to trying to go a bit much over mandrel diameter. Been a while ago, so I don't remember all the details, but I abandoned the practice since.

I've had good results with the mandrels. I use them before neck turning of course.

Another use that has worked well with no concentricity issues, is for the sizing step.

I have some chamberings I load for that are just hunting rifles. I use standard FL dies. I've found that they give too much neck tension. My process is to size all of my cases without the expander ball then run them all through the expander die/mandrel. It's slightly oversized and gives perfect neck tension at about .002"

I just started into a brand new batch of Hornady 6.5 Creedmoor brass. I decided not to neck turn or do any other brass prep with this lot and see how they shot. All I did was to run them through the expander die, chamfer the case mouths, prime and load them with my normal load. The brass was about .005" shorter in head space than a fired case, but that was to be expected. I checked concentricity of the unloaded necks and they were perfect. The loaded rounds had no issues either as compared to my carefully prepped match rounds.

Yes, much better and I'm using a powdered dry neck lube in lieu of Imperial .... no risk of contaminating the powder and smooth as silk. I removed the expander ball stems from the dies I use a long time ago and haven't looked back.



I've also checked the concentricity of necks and cases at every step of the resizing process using both the supplied expander ball stem in die sets and tapered mandrels. IME, I get consistently better concentricity using tapered mandrels. I think a lot of this is due to expansion on the down stroke and the long highly polished taper of the mandrel. I also like the consistent 2 thous. neck tension but also need to add that is in part due to annealing your brass periodically. I have measured the diameters of a couple of expander balls in die sets against a couple of my tapered expanding mandrels and they are the same, that said, other manufacture expanding mandrels may measure up differently.

YMMV,
BD

Thanks guys.

I don't turn necks, but will be using the mandrels in place of the expander ball for sizing in my 7x57 and 280 Rem. If it works like I think it will I can easily buy other caliber mandrels. Consistent neck tension and better concentricity is what I'm after.

You guys know how to measure neck tension from a standard sizing die?

Measure the neck of a loaded round. Measure the neck of a sized case from your die.

The difference equals the amount of neck tension