If your shell holders does not securely grip the shell and firmly fit into the press during reloading, you are bound to have headspace and sizing problems. At RCBS they manufacture their shell holders to the industry's tightest tolerances, using only the finest steel.br /br /Shell Holder Rams and Adapters permit the use of RCBS Shell Holders on the presses indicated. Clip spring holds Shell Holder in place, yet allows rotation to any convenient angle.br /br /RCBS Shellholder #18 Fits:br /br /- .44 Magnumbr /- .44 Special