Not really sure how you are getting such low leaden salutes really. Doing the math you should be able to get a good 40k on shinryu. Even taking into account how much less dmg shinryu seems to take from magic.
Does QD bonus not work for dark shot? Even then should be 32kish
Well ok you could get higher with drinks and mab roll and going on dark day using ws torque/belt etc.
I mean ***even wasting one of my atmas on TH as a rng/thf I still hit 50k wildfires and it's not that much better than leaden salute.
Btw for max dmg it would be double QD (assuming that works) ascetics gambir going /blm or /rdm and blm roll. MAB in every slot you can find it except head neck and waist and main. Head should have +ws dmg neck should be a ws torque and waist should be ws waist or obi if it's dark day/weather and main should be plutos. All other slots are completely unimportant. Atmas should be cosmos griffin claw and either that crappy +dark synthetic one or ultimate/PW one.
Oh I forgot actually +ws dmg or tp bonus gun would be best option in that slot too. Doing all that you should be able to hit 80k on trash mobs 50k on shinryu. Oh zodiac ring would be good too if applicable.
I guess a better example is my blu does 25k on nms without really gearring for it no staff bonus no griffin claw with sanguine blade and it's slightly better with just brew.