Spell Level vs Spell Slot when it comes to Artificers' Spell Storing Item ability

Question

What I know and can look up:
Ring of Spell Storing can hold 5 Spell Slots (Ex: 5x Magic Missiles, or 1 Fly and 1 Invisibility)
and
Artificer's Spells Storing Item ability can hold a 1st or 2nd level and can be used up to 2 times Artificer's Int mod.

Question

Can you store a 1st or 2nd Spell using a higher level Spell Slot with this ability? Ex: Can you store Magic Missile (normally 3x 1d4+1 force darts at base) using a 3rd level slot (5x 1d4+1 force darts) with the Artificer's Spell Storing Item ability or is it only the base 1st/2nd level spell? Like only a (3x 1d4+1 force dart) Magic Missile that can be used up to 2x the Artificer's Int mod?

Answer 1

Yes and No. Rings of Spell-Storing and the Artificer's Spell-Storing Items are different.

The Spell-Storing Ring is a specific magic item, whose text says the following:

Any creature can cast a spell of 1st through 5th level into the ring by touching the ring as the spell is cast. The spell has no effect, other than to be stored in the ring. If the ring can't hold the spell, the spell is expended without effect. The level of the slot used to cast the spell determines how much space it uses.

While wearing this ring, you can cast any spell stored in it. The spell uses the slot level, spell save DC, spell attack bonus, and spellcasting ability of the original caster

Since the spells are cast to store them in the ring, it would be possible to cast these spells using higher-level spell slots. When you do so, the spell would be treated as a spell of the same level of the spell slot expended; if you cast Magic Missile into the ring with a second level spell slot, it would be a second level spell, take up two levels of space within the ring, and produce an effect as though it was cast with a second-level spell slot.

However, by contrast, an Artificer's Spell-Storing Item, despite having a similar name, works entirely differently:

Whenever you finish a long rest, you can touch one simple or martial weapon or one item that you can use as a spellcasting focus, and you store a spell in it, choosing a 1st- or 2nd-level spell from the artificer spell list that requires 1 action to cast (you needn't have it prepared).

No spell slots are expended; when you produce a Spell-Storing Item that contains Magic Missile, you can't expend a second-level slot to make it fire an additional missile - and Magic Missile is only a second-level spell when cast from a second-level spell slot.

Answer 2

Spell-storing items don't cast spells

Spell storing items product the effect of a spell. Rings of spell storing allow the wielder to cast the spell.

If you produce the effect of a spell, it is not "cast using a higher level spell slot", because it is not cast. You always use the base level of a spell (unless specific text says otherwise) when you produce the effect of a spell.

This also means a Spell-storing item cannot be countered.

That being said

You could possibly convince your DM that a 2nd level magic missile "spell" could be stored within the spell-storing item. In 5e spell design, 1st level spells cast as 2nd level spells are intended to be weaker than real 2nd level spells; the upgrade from upcasting is supposed to be less than the upgrade from 2nd level effects.

Artificers lack of decent direct damage spells, and the high power of magic missile as a spell, do make this less true.