Traveller
As Richard has already pointed out, a key article is this:
The Ecology of Piracy on the Spinward Main - Steven Sowards. JTAS 19, 1983, pp.9-11 & 21 - discussion of the practice of piracy and how it might occur in the Spinward Marches; notes on the five worlds that combine the technical and political requirements to make pirate havens

But there are more:
Fleshing Out the Belt - Roberto Camino. JTAS 6, 1980, pp.6-9 - Includes missionaries, conglomerates, pirates, espionage, Lloyds of London, hiring out, convicts and more to spice up adventuring in asteroid mining

Chosen at Random: A Vargr Scenario - Gary L. Thomas. Challenge 27, 1986, pp.17-22 - the players get involved in tracking a Vargr who isn’t setting up a new company of merchants, but a company of pirates

Vargr Corsair Bands - J. Andrew Keith. JTAS 21, 1984, pp.9-14 + cover - discussion of some of the most general features of Vargr corsairs, from organization to equipment 

Krimm’s Paw: Adventure Number 15 - Nancy Parker. TD 15, 1989, pp.4-13 - Akidda Laagiir and his three companions encounter pirates at Pierson (Daibei 1536) as they continue their tour; deck plans for Krimm’s paw, a pirate corsair

MegaTraveller
Castran Marauders: Lords of Thunder: Pirates and Pirate Bases - William H. Keith. MTJ 4, 1993, pp.38-43 - background and details of pirates encountered in Gateway sector [3,0].

Snapshots of the Occupation: Life Under the Vargr Corsairs -James Holden. MTJ 2, 1991, pp.47-52 - two reporters for the Corridor Chronicle describe a year spent travelling through Corridor sector [-2,1]

Four Kings: A Traveller’s Overview - John A. Theisen. TD 14, 1988, p.27 - notes on piracy in the Jardin subsector of the Solomani Rim [0,-3] with the background of a pirate group and their ships

Into the Gap - Greg Videll. Challenge 62, 1992, pp.20-25 - set in the Duchy of Oasis in Zarushagar sector [-1,-1], the adventurers must locate and eliminate a pirate base in deep space; deck plans for a Type P corsair (the deck plans for the Type R are based on those in Traders and Gunboats: Supplement 7)

Mistaken Identity: MegaTraveller Adventure - William W. Connors. TD 15, 1989, pp.14-18 - the characters jump to a world where they are mistaken for pirates and once they clear their names are soon fighting off a pirate attack

Defying the Wolf: A MegaTraveller Adventure - Rob Caswell. MTJ 2, 1991, pp.4-18 + cover - an adventure starting on Gabrael (Deneb 2807) takes the adventurers into the heart of Vargr occupied Corridor sector in search of a missing courier ship; system map for Dywosik (Corridor 0614) and ship details for a 400-ton Vargr corsair

Pirates of the Blood Asteroids - Marcus L. Rowland. Challenge 42, 1990, pp.40-41 - intended as a campaign sub-plot for any suitable campaign, The Traveller Adventure for example, this adventure involves the players’ ship being used as a graphic in an advertisement for a computer software game  [not really what you’re after I suspect, but included here for the sake of completeness!]

The Pirates of Tetrini: MegaTraveller Adventure - Greg Videll. TD 21, 1990, pp.17-26 - starting at Cossar (Zarushagar 2424) the PCs are involved in a mission to investigate a possible pirate base

Random Nuggets - James Maliszewski. Challenge 56, 1992, pp.18-21 - six patron encounters, each with six possibilities: Noble, Ex-Marine Officer, Scientist, Professor, Pirate and News Reporter.

Snowblind - Dennis M. Myers. Challenge 45, 1990, pp.22-29 - set in the Zeno system (Delphi 0339), and on Vashtii (Delphi 0721) the PCs rescue a ship from pirates and then discover the pirate’s hidden base [I had the privilege of playing this under Dom Mooney’s excellent refereeing at TravCon one year.  A highlight was being knighted by Margaret at the end of the adventure.  (of course that was before I got to play a navy Lt pregnant with Norris’ child a subsequent year and Emperor Strephon a year after that!)]

Gold Fever - Kevin Berry and Andy Lilly. TC 9, 1995, pp.7-12 + cover - an adventure for use in any era in which the PCs are contracted to carry geological samples wanted by both pirates and terrorists

Raid on Lobok! - Mike Mikesh. TC 5, 1994, pp.39-[45] - Vargr start to move in on Imperial worlds after the shattering of the Imperium; this adventure, set in Ian subsector of Corridor [-2,1], gives the PCs the opportunity to be Vargr corsairs

TNE
The Pirates of Pinafore or The Computer Who Loved a Lass - Scott Kellogg. TC 8, 1995, pp.19-22 - a delightfully light-hearted adventure that involves several plots and ideas from various Gilbert and Sullivan light operas

Operation: Wolf Snare - Mark Lucas. Challenge 75, 1994, pp.26-34 - set on Daarida (Diaspora 2426) the adventure involves the hot recovery of a 200-ton starship being used for piracy and extortion; deck plans and details of 200-ton Cobra class corsair