Well,
Civilian Guild guns were made in various grades. Some were made on ex-military receivers / barrels / parts while others were made with in the white parts... so, each case is different. Many times, you won't know who made it, but only who "paid to have it built"...
As military "guild guns" goes, they usually supplied parts which were assembled at one manufacurer (not unlike the LSA and SSA L-E were built). The guild then was a sub-contractor for a major plant, not the assembly plant itself. Usually, the assembly plants were spinn-offs or subsidiaries of bigger manufacturers. These plants may or may not have produced parts and / or used parts from the major plants.
The guilds were much more active prior and in the 19th Century and to a lesser extent in the early 20th Century and beyond. Of course, in war time, they were put to contribution.
But usually, when we talk about guild guns, we think "civilian".