Can a Bag of Holding be used with Astral Projection to move items to or from the Astral Plane?

Question

The astral body you project through the Astral Projection spell "replicates" your possessions while leaving them physically alongside your real body.

Previous questions have argued that Bags of Holding open up to a separate extradimensional space. I interpret that to mean that the extradimensional space is distinct from both the starting plane and the Astral Plane¹

Assuming that the 'replicated' Bag of Holding on your Astral form functions² would it be possible to:

1. Have someone on your original plane open the physical Bag of Holding with your body, place an object inside the extradimensional space inside the bag, and close it.

2. In the astral plane open the "replicated" bag, and reaching into the same extradimensional space and therefore remove the real item (not just a projection), and close the bag.

3. Repeat

My first thought is that this wouldn't work, because the Bag of Holding on your projected form is a replica that might just have the appearance of working, with everything in it being only a replica as well ...but it seems by that logic any item projected along with your astral form would also only 'be a replica' and thus not work.

But if this did work, it might be more efficient (but slower) than using a spell like Gate to move objects or carrying them on your person as in other spells.

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¹I found someone indicating that Bags of Holding in earlier editions actually connected to the Astral but this does not appear to be the case in 5E based on the item description.

² Admittedly I am not sure that's a safe assumption— apparently this is also different in earlier editions

Answer 1

This is up to the DM.

The spell description simply does not give us a clear idea of the relationship between your real possessions and those possessions you have while under astral projection. Your question here goes well beyond the scope of what the spell description tells us, so you will just have to work it out with your DM. So before you try it, talk to the DM about it so you can come to an agreement away from the table, so you aren’t disappointed if your expectations are subverted by the DM surprising you with a disappointing ruling.

Answer 2

You may be able to do what you want with a Demiplane

As Thomas states, with a bag of holding you run into the question if the replicated bag is the same bag as the original bag. (There also is the question of what happens to replicated consumables, are they independent of the original ones and can be used "for free", or will using them affect the originals?).

As Astral Projection is a 9th level spell, and 90% of all D&D games stop by spell level 5, I would not hold my breath for a Sage Advice clarification on it, either. This will be up to your DM to decide.

However, you can get around the problem by using demiplane. If you are a wizard and have level 9 spells, it should not be an issue to have this level 8 spell either. Put everything you want to access in the astral plane "for real" into the demiplane, if needed on the prior day. Then, when in the astral plane, call up that same demiplane by using the spell again. You will have access to all your real stuff.

Answer 3

It would appear the bag of holding is a replica, not the same bag. We can reach this conclusion from these snippets of the spell description:

Your astral body resembles your mortal form in almost every way, replicating your game statistics and possessions.

This seems to imply that the possessions are considered part of of your mortal form, for the purposes of this spell, and they are replicated to your astral form.

Your astral form is a separate incarnation. Any damage or other effects that apply to it have no effect on your physical body, nor do they persist when you return to it.

So what ever you do to the bag of holding while in the Astral Plane do not apply to the "mortal form". And, this also implies it works the other way around, anything done to your mortal form does not affect your astral form (except either form dropping to 0 hit points ends the spell, explained explicitly).

So, while it is not entirely explicit, it is very strongly implied that once you have your replica astral from, including possessions, are separate incarnations.

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However, this is still not very helpful. Yes, the Bag of Holding is a replica, not the original, but does the replica access the same extra-dimensional space?

If it does access the same space, and you take an item out in the Astral Plane, what happens to the item, when it suddenly is a real item and not an Astral projection? And more importantly, what happens to a replica item, when placed in the replica Bag in the Astral Plane?

If it does not access the same space, then is the replica bag empty, when opened in the Astral Plane, or does the spell also replicate the extra-dimensional space and it's contents?

There are even more options. Perhaps the replica BoH simply does not work, it can't access the original extra-dimensional space, and it does not have its own.

These questions are left for the DM to answer, but I hope the above points will allow making a more well-reasoned ruling, or for a player to argue for the ruling they'd like.

As a purely subjective, personal ruling, depending on the campaign, I might allow transferring items between Astral and original plane by giving access to the same extra-dimensional space, so players would be able to do more stuff in and with the Astral Plane. Or, if wanted to keep Astral Plane as just a small diversion, a means of travelling, then the replica bag would simply not work, it'd be like an ordinary bag, so players would not waste time by fooling around with it.