I've just managed to get an Xbox One to play year 3 content and I've heard that dismantling a year 1 Gjallarhorn will give you a schematic that let's you build the year 3 version.
Can the same be done with a year 1 Thorn to save all the palaver with the exotic bounty or do I have to do it the old fashioned way?
If I understand what you're asking:
Will breaking down the Y1 Thorn give the schematic for the Y3 or do I have to do the bounty / exotic quest means of procurement?
No. Y1 Thorn doesn't give a schematic. You'll have to obtain it the old fashioned way.
Only your original Khvostov will give you a schematic if you dismantle it.
To get the Y3 Thorn, you need to do the weekly bounties from Shiro-4. When you turn them in, you have a chance to get the new Thorn quest.
