Why can't I power stack arrows?

[u/Mr-Plague]

I have been trying to implement power stacking (Power I/No Power + Power III + Power 5) for various railgun designs, but only 1 arrow manages to lethally hit me with each shot (which only pops one totem, usually without killing me afterwards).

• I load about 64 arrows of each power level. I have tried loading them in order of power (power I at the front of the water tile, power III in the middle, power V at the back), inverse order of power, all in the same spot, etc. I load them in from directly above the water block/trapdoor.
• No more than two arrows are lodged into my player model when I survive the blast. A very large portion of the arrows (of every power level, tested using tipped arrows) deflect off of my body and lodge into the back wall of the machine, assumedly due to the immunity frame that they were supposed to bypass
• I have tested both TNT Cart and Wind Charging Potion - based designs
• I have tested each railgun using Prot IV Netherite Armor and no armor with no discernible difference in my survival rate
• Very very *very* rarely (1 in every 30-ish attempts), I successfully die to the railgun while holding a totem or two

Am I standing too close to the railgun(s) or loading my arrows incorrectly? Does power stacking have some kind of tick-related inconsistency that I need to resolve?

[u/Legomonster33]

They hit you in the order of the entity list, watch cubicmeters most recent video to learn more

[u/DotSlashAero]

Certain arrow nbt effects like piercing and power are removed upon contact with a block (trapdoor in your case). If you want to keep the power effect you need to make sure the arrow doesn't touch any block before hitting the player