Holding a GC while sizing it

[PopcornSutton]

I seat my Gator checks in a hand die I made that holds the bullet aligned and seat them with an arbor press. I know that at least then, they are seated to the bullet base and square. I then run them into a sizing die, base first. When they come out, they aren't flat anymore, there is a dish in the check, and I have no assurance they didn't cock going into the sizing die, even though my rig has an ejector rod that is held at the top of the stroke that I press against. But for sure, they were flat when I seated them at first, then with the crimping/sizing, the dish forms, which means the edges may not seated firmly against the bullet base anymore.

Seems a method of holding the check against the bullet base WHILE sizing would not allow that dish to happen. Ideas?

Accuracy is the goal here, the base is important.

[Winger Ed.]

my rig has an ejector rod that is held at the top of the stroke that I press against.

When you bear down on the lever, there's no pressure holding the rod up and it will free float going down
until it hits the depth/stop adjustment point.

To seat them on the press- put a flat piece of steel over the die.
Someboby makes a special little tool for doing that, but anything flat and about 1/8" or so thick will work.

I'd wonder if the check is really seated that well to start with.
I use Hornady checks out of habit, and can feel and almost hear sort of a click when they are fully seated,
and the boolit will stand straight up on the bench before I size and crimp it on the boolit base.

The cup on the rod helps keeps all the pressure around the edge of the check where it needs to be to get a uniform crimp.

[PopcornSutton]

Well, that is a good idea, I could cup the rod to push against the outside edges instead of flat. Thanks.

[Winger Ed.]

Well, that is a good idea, I could cup the rod to push against the outside edges instead of flat. Thanks.

You're more than welcome.
It just popped into my head, so I did a edit to describe seating the check on the press too.
Good luck with it.....

[Hick]

I did some experimenting awhile back on group sizes and gas checks seating. What I found for me was that the group sizes were excellent and the same regardless of whether the gas check was flat or dished--as long as it was even (in other words, the checked bullets stand up straight on the bench). If the bullets would not stand up straight group sizes went up.

[Bfb]

Not sure which way you are “dished “ but just run a gc thru THEN put that gc on seating stem and run them thru. That wil take up difference between forming pin and and shank of gc. Basically make a gc and use that as a spacer in your die

[725]

I seat my GC's with a "C" Lee press. I made a flat to install as you would install a shell holder and then I milled a bolt flat to thread into the area where a die would thread into. End objective is to have two flat surfaces approach each other when the ram is run up & down. Works primarily for flat meplat and bolts that don't mind a little flat on the nose. Hollow points are OK if they have substantial girth to withstand the pressures of seating the GC. Quick and easy and it firmly seats those that are difficult to get all the way on. Then I run 'em through a sizing die in another press.

[tward]

My SAECO and Cramer lubesizers have a little cast arm that swings out for gas check seating, the boolit get aligned with the top punch and is squished down on the gas check. Tim

[Rapier]

You can use a 1/8" thick steel plate, 1" wide to cover the sising die hole, seat the GC against it with the top punch. I use Hornady GCs because they crimp onto the bullet base.
Any more, I just PC bullets with a GC. I get plain base bullets.

[country gent]

depending on the amount of dome you may be seeing a thing thats been known in the die making industry, When you size a cups dia down the area reduces and the base is to big causing it to dome

[PopcornSutton]

depending on the amount of dome you may be seeing a thing thats been known in the die making industry, When you size a cups dia down the area reduces and the base is to big causing it to dome

Understood. Since this dish forms with the edge "high", I recut the bottom of the stop with a taper inwards. I tried a 4 degree in the compound and tried seating a check, and the base was then domed outwards, so I moved to 3 degrees, and they look nice and flat. Essentially, forced the edge farther. I'll see how they shoot.