The one oversight in this game is an indication how concealable weapons are.

How easy can you hide a Laspistol or Stub-automatic on your body, can you hide a shotgun under your longcoat and what about that Armageddon Pattern Autogun?

Okay we have the compact enhancement but not all weapons should require such things to be concealable.

My try:

Coat: Anything you can hide under a short jacket or under a sweater
This would include most pistols (save bolt), daggers and fist loads

Longcoat: What you can hide under a trenchcoat
This would include the pump action shotgun, all carbines, boltpistols and handcannons, even some swords might work.

Space Hulk: Anything you hide in a Space Hulk such as heavy weapons
Rifles, Heavy Weapons, Grenade Launchers, zwei handers , etc.

Santiago said:

My personal inclination is to require a Stealth or Sleight of Hand test to conceal a weapon about your person. The longer you spend concealing the weapon (and the more thoroughly you conceal it - which itself comes with a cost), the easier the test gets; similarly, loose or specially-designed clothing and similar can improve your chances. The bigger and bulkier the weapon, the harder the test gets (as a rule of thumb, +0 for pistols and small melee weapons, -20 for Basic weapons and the majority of melee weapons, -40 for Heavy weapons and two-handed melee weapons, +10 on top for Compact weapons). Thoroughly-concealed weapons aren't as easy to retrieve from their hiding place, making it take longer to draw them (a pistol in a concealed holster under your jacket is relatively easy to hide from cursory glances, but a detailed inspection is fairly likely to find it... but in turn is readily accessible. Meanwhile, the compact autogun under the false bottom of the holdall you're carrying is a lot more thoroughly concealed, but also more difficult to reach quickly)

I believe the DH main book says you should use the Concealment skill vs Awareness or Search. The modifier are pretty subjective. (Other than the bonus for the compact mod in the weapon section.) At lot of it depends on the size of the weapon, and if you are being searched vs just looked at. A pistol under a coat is easy to hide from some one looking at you, but very hard to hide in a pat down.

It's 40k.

Even pistol weapons are larger than normal, the Autopstol is larger than a modern SMG or Desert Eagle.

Concealability of anything larger than a 1 shot hold out pistol type affair should come with major negetive modifers.

Velvetears said:

Not larget (as I can tell from the illustration), but heavier. Heavy is good. Heavy is reliable.

Otherwise, the laspistol is no larger than a normal 9mm pistol (even described as compact), and stub guns seems to vary but usually no more than 50% heavier than RL counterparts.

Then again if you can hide an Uzi or Mac10 then you can hide a DH Autopistol!

I suggest using common sense for most of it and require a test (Concealment or Sleight of hand, I'd go for the latter) in grey areas.

It is possible to hide alot of weapons with some thinking, but doing so comportably over time and keeping readiness is not easy. Thus generally speaking pistol sized weapons I'd let people conceal easily (unless searched). I'd not let an Acolyte conceal an Autogun or larger weapons over time in an urban setting though!