As armorer desynths I am getting doubles from Hell's Kitchen in a number range of 100-150 (I believe I stopped at the 158 mark ,my notes are not with me atm, and moved up to i55s armors for more skill up per success) but overall I recieved more singles then cobalt skillets at a rate of ~3/10 attempts which was an improvement as i was 2/13 with the level 43 recipe. So I recommend trying to get something in the recipe range of 47 but under 50 as 50 yields fieldcraft II's. So electrum needle would be that criteria but your results with the lesser craft match mine with the upper so as it is cheaper no real reason to change it.