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RBT starter/core seat die, type -S
RBT starter/core seat die, type -S Quantity in Basket: None
Catalog No.: BT-1-S
Price: $249.00
Shipping Weight: 0.50 pounds
Enter bullet caliber (diameter) in inches:
Select external punch:
Open tip
Lead tip
Open tip hollow pt.
Lead tip hollow pt.
Select a SWC nose shape
Open Tip external punch diameter (if known, to fit jacket ID):
Enter optional nose shape description:
Optional Note:
  Discover CS Punch diameter for my jacket/core combo ($25)
Sample jackets for fitting punch:
Yes, I AM sending 6 jackets
Use Corbin jackets, specified below
I sent 6 jackets before ordering.
I am NOT sending any jackets: just guess!
Corbin Jacket Cat.No. (if using our jackets):
Enter finished bullet weight to be made:
This is the first half of the two-die RBT-2-S set, used to seat the lead core into a jacket and form an angle on the bullet base, in preparation for finishing the RBT base in the BT-2 die.

Bullet jackets are typically flat base when you make or buy them. The pressure of seating the lead core into the .001- .002 inch undersized jacket, and expanding it in diameter, also can be used to reshape the flat base into an angled boattail shape (which lowers the drag and increases the BC or ballistic coefficient of the bullet).

The BT-1 die replaces the usual CS-1-S core seater. You do not need to seat the core first, and in fact, that will cause problems with getting the jacket into the BT-1 die. Put the loose core and jacket directly into the BT-1 die, and seat the core using the appropriate diameter core seating punch (which must fit the ID of the jacket at the particular length of core you choose, for a given weight of bullet).

You can tell when you have used enough pressure, because the base of the flat jacket will become a sort of truncated conical shape, providing an angled base section that uniform and well defined. The base left on the end of the jacket should be the same diameter as the ejection punch (internal punch, which fits into the threaded end of the die and stays internal or inside the die and ram during the entire operation).

This die is sold separately as a replacement, not as a stand alone product. While it will make a conventional boattail shape on the base, you will need to use a punch with a similar shape of cavity to push it into the point form die and make the ogive. If you do this without first completing the RBT base in the BT-2 die, the punch edges will automatically form a less than perfect step or rebate that will vary with the amount of pressure it takes to form the ogive on a given jacket. It is far better to pre-form the RBT base exactly, using a second die, than to get variable rebate step shapes depending on pressure, jacket hardness and thickness, core ductility, amount of lube used, shape of ogive, and other sometimes changing factors. That is why we sell the RBT set as a two-die package with a matching base punch for the point forming die. It is precise, consistent, accurate, and it works!

The die set comes with an internal punch (ejector), and an external punch which is a core seating punch. It is usually (by default) the size and shape for a standard open tip bullet in a commercial jacket, but the diameter has to fit the ID of your jacket. If you do not know the diameter that you need, you can use the "note" to let us know which jacket you are using and about how far down into the jacket you will be seating the core. Then we can estimate the required punch diameter, or contact you if we need sample jackets or more info.
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