I am looking to set up a new rifle build and was looking to go the route of a custom action this time. I want to stick with SAVAGE threads for prefits so that narrows the field. I also would like to stick with exchangeable bolt heads. While I am at it, I want a left hand action, going short action as well. I know what a pain.. I have looked at: Big Horn TLS and origin Nucleous Are there others I should consider?