[MC-301020] Piercing arrows do not pierce as expected at level IV when hit entities are on the same block

I was playing on my survival game and was going to complete the achievement of killing 5 different mobs with one arrow until I tried several times with a level IV piercing crossbow to complete the achievement and it only pierces 2 mobs, sometimes 3 but nothing more. The achievement cannot be completed.

Linked issues

relates to 1

MC-298767 Piercing arrows phase through mobs with the same hitbox size that are in the same block Open

Attachments

2025-08-26 15-04-08.mkv

Comments 9

Yamato320 2025-08-13T17:27:38Z

Fix: Arrows don't pierce when mobs are all together in a 1x1 space. Previously, it was possible to kill all mobs in a 1x1 space.

Yamato320 2025-08-19T23:47:55Z

Still present in Minecraft Snapshot 25w34b

ampolive 2025-08-20T23:18:41Z

Does this issue occur in 1.21.8?

Yamato320 2025-08-20T23:38:01Z

@ampolive, I have to check, but I'm very busy. I'll try to look later.

Yamato320 2025-08-22T18:36:50Z

Confirmed, it is present in Minecraft 1.21.8.

ampolive 2025-08-22T22:11:30Z

Do the mobs have the same hitbox size or are they in the same block? Could you please attach a screenshot with your setup in order for me to reproduce this bug?

Yamato320 2025-08-22T22:33:01Z

I've tried the mobs with different hitbox sizes. Yes, they're all in the same block; the error only occurs when they're all close together. Regarding screenshots, I'm unfortunately unable to do so because, since version 1.21.5, all the videos and screenshots I take appear black. Sorry. @ampolive

Yamato320 2025-08-26T21:54:35Z

It's still at 25w35a. I managed to convince someone to record a video of the error for me:

[media]

Tonohe 2025-08-26T23:55:30Z

It can be confirmed