Honestly IS tech needs to catching up to Clan stuff.
The clans have had their advanced lasers, missiles and PPCs since at least 2854 (reference the Coyotl). Since the Exodus happened in 2784, and then a second exodus in 2801, that means that the clans seem to have pocket wizards and the IS are intellectual morons.
In the span of roughly 70 years, or 53 years, the clans created laser weapons and missiles that were more than twice as effective as their IS counter parts. The IS, even ignoring everything up to the Helm core, still gives from 3037 to 3150 or roughly 113 years, including have examples of clan laser tech from 3050 onward (i.e. 100 years), to have played catch up to the clan laser tech which has basically stalled since 2801.
By 3050, the I.S- on it's own, was able to reproduce most of the lost Battlemech technologies of the Star League that they had lost to the succession wars. (XL Engines, Ferro-Fibrous armour, double heatsinks, ER Large Lasers, LB-X 10s, UAC 5s, etc.)
By 3055, the I.S was producing its own Battle Armour, ER and Pulse Small and Medium lasers, SSRM 4s and 6 racks, the Lbx 2,5, and 20, the Ultra 2,10 and 20, and all technology that the Star League never quite achieved.
By 3060, they could produce Clan technology (See Maximum Tech) and had working prototypes of X-Pulse Lasers, Hyper Velocity Autocannons, Light Autocannons, Angel ECM, Light Engines CASE II etc. -all technologies that significantly surpassed the Star League era. In additional, they had developed entirely new weapons such as Light and Heavy Gauss Rifles, C3, Stealth Armour (that is arguably better than Null-Sig), stealth armour for BA (that was the basis for the void-sig) that puts the Chameleon light shield to shame, as well as things such as Blue Shield, XXL engines, Reflective armour, Tandem Charge SRMs and LRMs, and Extended Range LRMs. Most of which was completely innovative and puts the Clans to shame in that field (The Clans are typically limited to making improvements of existing technologies). Don't forget the Direct Neural Interface from the NAIS...
By 3067 we've got technologies that arguably surpass their Clan counterparts (MMLs and Plasma Rifles) as well as gear the Star League never even dreamed of- C3i, Heavy PPCs, Light PPCs, etc.
By 3075, the I.S are producing Clan grade Prototypes (XTROs)
Hell, the Clans showed up in 3050- the I.S took less than a decade to begin churning out their very own Omnimechs (Draconis Combine comes to mind. By 3058, they had Omnimechs in full production and on the front lines. This means no later than '54 or '55 they had working prototypes).
It's not just knowledge. You don't take a Clan ER PPC, open it up and say 'Gee, well that's how it's done...wow, we're stupid'.
If you go back in time to Apollo 11's moon landing- where all of NASA's equipment could be summed up by today's pocket calculator, and gave them an Intel i7 Processor...do you really think they could replicate it within a couple of years? They didn't have the knowledge back then to even conceive a microprocessor, let alone the facilities to create one from the 1970s. We're seeing the same thing here. There's far more than just the technology of the weapon- there's the materials that go into it, the refinement, the infrastructure (The Clans brought their own facilities to the I.S, and have to convert I.S factories up to Clan grade before they can produce Clan 'mechs, remember?)
To use the CPU example, modern day (Clans) introduced a modern microprocessor to the 1950s (I.S). Within 5 years, they were producing the equivalent to the 1970s processors (basic Star League) and within 10 years they were producing early 1990s (advanced beyond the Star League). They could also produce modern CPUs (Clan tech) but only by hand and at great cost. Within approximately 15 years, the I.S has narrowed the gap so much, I'd say they were mass producing the equivalent of early 2000s CPUs.
If the vitriol about the Dark Age Era is to be believed, and based on the XTROs, the I.S will likely be producing Clantech by 3100.
