I own and use a Crossbow Pulse machine that is based on the Hammer head platform it was made by George who co owns the Geotech forum,the 10'' coil was of course matched and it does work very well indeed,since i have own it i have added additional coil but rather than have the frustration of winding and tuning them myself i was able to buy brand new Garrett Seahunter coils from the biggest dealer in Birmingham,it does not take much working out who i am on about.But these coils work superbly well as that was done was change the coil plugs over and i think George added a damper resistor inside the control box for me.
Curently use both the 8'' and 14''x10 Garrett Mono coil,also have been working on a 18x12 coil using a Coiltek coilcase that i was able to buy brand new but although i have had it working not sealed it as yet,but i also had a 5'' coil made by a forum member that was shipped over from Canada,it does work well with the Hammerhead setup but you do need to adjust the delay just right to get it to work exactly right.
As building coils can be a hit and miss thing when building a PI machine this is the reason i went down the route of getting a ready built coil from a main brand name and i i feel this eliminates the headache of building a coil and setting it all up,and the Garrett Seahunter coils are ultra cheap to buy brand new as well.
Good luck and hope it all comes together for you.