You can get regular weapons into Battle Labs with custom loot pools (High Explosives, for example) by using the tent stash feature. Sadly, you can't stash items while in Battle Lab, so
Fortnite Status on X: "Due to an issue we've temporarily disabled Tents. Your stashed items are still intact and will be accessible when the Tents are back. We'll update you when we
Where To Find Abandoned Tents In Fortnite - GameSpot
Fortnite Chapter 3 floating tent glitch guarantees a Victory Royale when done correctly
I Still Have 2 LEGENDARY MK'S In My Tent! - Fortnite - Chapter 3 - Season 2 - YouTube
Fortnite Disables Tents in all Playlists | Fortnite News
Claim an abandoned Tent Fortnite Locations - YouTube
Where do abandoned tents come from? Are they the ones placed by players currently in the match in previous matches. Why are some of them in the same location every game? :
NEW* Fortnite Chapter 3: What Are Tents? (Tips & Tricks!) - YouTube
Fortnite YouTuber is hijacking tents and messaging their owners
They are still available in Tents if you stored them during Winterfest : r/FortNiteBR
Where To Find Abandoned Tents In Fortnite - GameSpot
Where to find tents in Fortnite Chapter 3, season 3 - Dot Esports