No they're not; the Davions are. The Mariks have always had a fetish for lasers and LRMs. Their ballistic expertise is fairly limited, all things being equal; they re-engineered the LB-5X and Ultra-10 autocannons from SLDF-era records and scaled the gauss rifle to its current "light" status, but that's it. Compare that to being the re-engineering of the ER medium and small lasers, plus the plethora of LRM submunitions they came up with.
Actually, in the last few decades (approximately 3080-3140) the Mariks (from the Marik-Stewart Commonwealth) fell in love for Autocannons.
Honestly, it wasn't as much as a case of "love" (although I would admit that perhaps they decided to favor more direct approach than their traditional LGRs and LRMs), but the fact that they lost access to some other factories of the former FWL.
However, they were left with the Imperator Automatic Weaponry plant on Atreus, known for producing fine ballistic weapons such as various Autocannons and Gauss rifles.
Thanks those factors the Mariks used such ballistic weapons on their refitted and upgraded 'Mechs and designed some new 'Mechs armed with those guns.
Some examples are:
- new 'Mechs: Shockwave SKW-2F/4G (RAC-5), SKW-6H (UAC-10), Thunderbolt TDR-9M (LGR), Anzu ZU-G60 (UAC-10)/J70 (RAC-5), Trebaruna (GR)
- refitted 'Mechs:
"Orions and Tempests modified ... to utilize rotary and ultra autocannons", Albatross (GR)
- their R10 ICV sports ballistic weapons on two of its three configurations
- Partisan AA vehicles, again with twin Autocannons; Partisan tanks with quad autocannons
- Red Kite was originally designed with Light Autocannon
- Poignard ASF (LAC)