As a previous owner of an M1014, I will relate to you what I encountered...
Regrettably, you cannot remove the M1014 recoil tube and replace it with an M4 tube. The M4 tube cannot be purchased as a spare part (to prevent us from converting the M1014 to a collapsible stock weapon).
The M1014 recoil tube is "permanently" welded to the receiver with a powdered European version of a "Locktite" compound. Removal of the "welded" tube requires a heat and torque application that will damage the attached aluminum receiver.
There is a gunsmith in Florida that will mill your M1014 tube without its removal. However, the dark finish that is on the tube will be ground off. The tube is stainless steel, and Benelli uses a proprietary chemical process that reacts with stainless to give it the dark mil-spec finish. It is NOT Parkerizing, as you might think. Parkerizing does not react with stainless. And the "polyresin" baked finishes wear off at the places of sliding contact.
Some NFA rules were not lifted for imported weapons, and the BATF is very sensitive to THIS gun in particular. Benelli took note, and went to great lengths to defeat our attempts to convert the civilian M1014.
My desire to own a legal and functioning collapsible stock became an obsession. So, I abandoned my conversion efforts and purchased a true M4.
[ 02-25-2006, 10:45 PM: Message edited by: jetflyer ]