Now, I am become Death, the destroyer of worlds.J. Robert Oppenheimer
The basic design of handheld weaponry did not change to any great degree in the decades leading up to the Exodus. Many avenues of research, into things like friend-or-foe recognition and smart bullets were deemed too cost-inefficient to be marketable. However, several small and incremental modifications were made - such as more efficient propellant, more robust firing mechanisms and faster chambering. Non-military defence hardware did not change much beyond this; proven designs were merely optimised in ever more minute ways as time wore on.
The colony ships, while not expecting military action of any kind, were nonetheless packed with cache of small arms and some heavier defence hardware (along with the blueprints for fabricating more as necessary). Pistols and submachine guns were distibuted to civil law enforcement, while larger weapons such as rifles (and in unofficial cases, anti-materiel rifles) were used in hunting of - or as protection from - the local wildlife. They were never intended to be turned on fellow colonists, but were more than capable of suppressing human foes were the need to arise.
Research into laser weaponry, driven by the self-fulfilling prophecy of science-fiction, was conducted throughout the 21st century and saw massive funding both during the build-up to World War III and whilst it was raging. Despite this, the practicality issues with a man-portable laser weapon (namely power consumption, efficiency and size) were never truly overcome and they remained heavy defence weapons that required extensive infrastructure. The theatre in which they excelled was as point-defence anti-missile emplacements - indeed, it was the European Missile Defence Shield that granted them almost total immunity from the nuclear exchange that marked the end of the War.
Electro-Magnetically Propelled Projectiles
EMPPs, such as rail and coil guns, were already well under development at the beginning on the 21st century. Their biggest flaw - the tendency to vaporise their own barrels during the firing process - was solved with the advent of improved nano-technology, as a new barrel could simply be fabricated during reloading. While the hypersonic rounds fired from these weapons gave an incredibly short time-to-target, the lack of drop-off made it difficult to "lob" rounds over obstacles, and thus made it inferior to modern artillery and missile technology. This led to the development of Orbital Kinetic Bombardment Weapons (or "Rods from God") which would give direct line-of-site to a target for a short window of time. This in turn led to many countries developing surface-mounted Anti-OKBWs.