Expand case or neck down a case

[rockhound78]

Have a 243 LBC (6mm Grendel) and thinking of either expanding 22 ARC cases or necking down 6.5 Grendel brass. Is one way better than the other?

 

[Oso]

Assuming not moving position of shoulder then:

Necking Up may result in doughnut as thicker walled shoulder material gets shifted into bottom portion of newly formed neck, and slightly shorter necks.

Necking Down may result in thicker walls of case neck and slightly longer necks.

That said, you are barely reforming the case in either direction so not that big of a deal. Depending on the donor brass headstamp, the case wall thickness will vary resulting in differences in the newly formed cases. You’ll need to tests against you chamber for fit.

Side Note: .22cal cartridges after being fired expand to approximately 6mm diameter along the neck. If you know a guy with a 22ARC then easy source to get a couple of spent cases to measure the potential changes.

 

[GLShooter]

I neck my Grendel cases down using Redding Type S FL bushing dies. I shoot three or four uppers and a Savage bolt gun in F-Class. I also make 22 LBC and 20 LBC the same way. On the 30 LBC/ARC I nexk up the 6.5.

 

[gunsandgunsmithing]

I've done tons of it both ways and both are pretty easy. Necking up will create a bit of a donut inside the case just above the shoulder. Necking down doesn't do this but the necks will thicken and lengthen a smidge. i shoot all three, 22,6mm and 30 grendel/major. Going from 6.5 down to 22 is best done in two steps but you don't need to worry about it with your stated intent. Going from 6.5 to 6mm, I do in one step with a 6br body die....very easy. Of course the BR die is shorter so ya just back it off to only work the neck. The body dies are hardened, which makes it easy. You might get a little flare at the case mouth but it's gone after firing and works great from there on. More than one way to skin that cat but that seems to work best for me.