Help fitting buttstock

Hello again. Im trying to turn the bolt holding my buttstock on so the front bottom handguard an sit properly, only problem is if i loosen the bolt to make the square notch level (see in picture) the buttstock becomes loose, but i cant tighten it any more so i cant fit my foreend on. any ideas?

Hello again. Im trying to turn the bolt holding my buttstock on so the front bottom handguard an sit properly, only problem is if i loosen the bolt to make the square notch level (see in picture) the buttstock becomes loose, but i cant tighten it any more so i cant fit my foreend on. any ideas?