in my little structural steel shop my far from scientific research and development laboratory scientists.  (ME)   have found 1/16" 71C from Lincoln to be the most productive way to weld d1.8 compliant welds in the shop.     1.7X faster than 0.72" NR-232 or Esab coreshield 8 when factoring interpass cleaning.    Just my observations.

Hello Dennis, I have opinions on the MCAW vs. FCAW, yet these are only that, my personal opinions. I did find a link from ESAB that might address some of your questions. I'll try to include it here.

http://www.esabna.com/us/en/education/blog/advantages-and-disadvantages-of-metal-cored-wires.cfm

My experiences with MCAW were first realized by a Lincoln rep. who brought a sample to an instructors conference that we were holding a number of years ago. At that time I found it to be very easy to use and also found it to work particularly well on tube steel or other materials that might have varying sorts of corrosion inhibitors (think in terms of tube steel or pipe/tube). It was also explained to me, in layman's terms, that since the core was "powdered metal" that it took less energy to melt than a similarly sized solid wire and thus improved deposition rates. I believe that this explanation applies in a similar fashion to FCAW wires.

I just re-read your post and would include that MCAW is NOT an all-position wire and positioning of the weldments would be required for your out-of-position work.

I will be interested to hear from others as to their opinions/evidence to explain and answer your question further. Best regards, Allan

If you need all positions, MCAW is out.  While some GMAWP parameters can run metal core out of position, the deposition rates are very low compared to FCAW.

ESAB 710x  1/16"  will give you about 8 lbs an hour vertical up with 100% CO2 gas

.052 L56 solid wire with a Lincoln S500 will give close to 14 lbs an hour easily in flat and horizontal fillets, which might compete pretty well against MCAW.