How has everyone handled their explorers getting customised weapons? Has the explorer customised it themselves (with an extended tech use test) or have they found someone else to do it for them. I'm asking as I can see how a voidmaster for example would be able to strip and rebuild a lasgun as their built for ease of use but can't really see one taking apart a plasma gun.

An extended Trade (Armourer) or Tech Use, whichever is better, with the difficulty modified by the rarity of the weapon the same way rarity affects the acquisition roll.

I would limit modifications beyond the trivial (sawed off, new grip, etc.) to explorators and tech priests.

Imperial tech is deceptively advanced and dangerous to work with without training, and the adMech has a habit of murdering people who mess with their tech too much.

As far as teh adMech is concerned everything more advanced than a stubber is "on loan".

Thanks for the advice as all four explorers who have hellguns are looking towards customisation to get the reduced reload time benefit from the rule book .

Ehr, customising Hellguns is rather pointless, unless they all have like strength and toughness 50+, those powerpacks weigh 25kg, they are NOT standard mag's...

I would limit modifications beyond the trivial (sawed off, new grip, etc.) to explorators and tech priests.

You're forgetting the true master of kustomizing da stuff: Mekboyz!

Other than that, yes, allowing lay persons to modify weapons won't be too good for your relations to the AdMech. RT characters will certainly be cut some slack, but it's a nice way of getting yourself a Rival talent.

In my group the Arch Militant used his starting acquisition to buy a custom made autopistol (based on the Orthlak IV (IH)), besides it having a motion predictor it is also customised.
He is the Rogue Traders bodyguard...