Germany will fund 200 Ukrainian-made Marta howitzers, a new Bohdana variant on a Mercedes-Benz Zetros chassis with a 155 mm L39 barrel.

Note similar rationale to producing 39 caliber (barrel length) 155mm towed bohdana, mainly lighter weight and also a whole lot of 155mm shells countries are willing to donate were designed for 39 caliber barrels.

Though it is also intimidating to focus on mass producing artillery and choosing the most up close and personal barrel length…

edit It also might be a good barrel length to focus on for soft recoil minimal weight setups.

https://en.defence-ua.com/industries/why_ukraine_is_developing_shorter_barrel_howitzers_despite_their_reduced_range_such_as_the_new_domestic_marta-16982.html