well, if you consider, say you have 100 units of 80q weapons, and you replace 10% of them via resupply with 170q. if the weapons q isn't altered, the q of the weapons will increase by 10q, to 90ish. (89)
in my case, the LRD that i'm referring to, well, i make my c3 raiding lrds all the same, 600 each ht/ha, and the rest mrmb, about 1m ammo each for the ht/ha, and 90k ish for the mrmb. i had used a considerable amount of mrmb, mrm, and hta/has in raiding. probably over half the original. if my resupply had not be altered in enroute, then i could have expected 110-130 final q. i can except a small amount of q degradation during the process, so i'd been happy with 90-100 final results. but instead, i ended up loosing money, for no benefit.
i guess thats the point i'm making here, i received ZERO benefit, from buying high q weapons/ammo. that is, when resuppling.
also, consider, that you can buy 250q weapons and ammo. when they are put into garrisons, the gars will start out at 80q, regardless of Q.