i noticed when i put the barrel in the upper receiver that the barrel extension seemed a little loose in the upper, there was a slight bit of up, down ,left and right play. i did not torque it or tighten the barrel nut i just wanted to see how it went together. should it be loose oe a tight fit before torqueing? i know it will tighten up after torqueing but will there be movement when fired? i bought a used upper maybe thats it but it looks fine. i just ordered a new stripped one from bm, i'll see how that fits.

 It has to be tightened.

thanks Waldo,
i kinda figured that, but i had to know for sure anyway. now all i have to do is get my lower back that i sent to DPMS six weeks ago to get refinished. yeah, i know, i should have sent it to someone else, i'd probably already have it back.