It certainly seem so. I burnt my ammo like water.
On the other hand, pay attention to ammo they carrying. NPC doesnt pick empty case or drained energy cells, so you have nothing to recycle. if you equip them with rare caliber (12.7mm and .45-90 govt) you are in a world of hurt, shopping-wise.
EDIT: On the other hand, pay attention to details. companions cant change their ammo: either the standard stuff, or that single type of ammo they can use. So if there's different type of armored level, their shots may not punch through. Which is where you come in with VATS sighting and selective fire. Shoot the heavily wounded and the heavily armored with your selection of HP, AP, and handloaded ammo.
And note companion states, too. Very Hard can see them down to the last sliver of health if luck turn sour, or their weapons shot out of hand. With the penchant of jumping in the fray, Veronica might get mobbed in a blink and the only thing you can do is burying her in a nice dress. Dont believe me, just do a tour of Sloan or Dead Wind Cavern. Companion kill fast but get killed even faster.
