Thanks to all for tha help. I was in bind and ended up using 5 inch. I was using them to attach Toledo heads to Herters. I just bored out the hole a little to make the 5 inch work.
Tom Tschabold makes indestructable decoys. My son 9 year old son Thomas saved his money (I matched him dollar for dollar) and bought a dozen Super Magnum Mallards. He will be able to apss them to his grandkids without a single busted head. They are TOUGH.