[zepheris.hk]

I took this upper to the gun shop today and it fit tight on every lower they brought out...stag/noveske/cmmg etc and it was significanlty beefier than even the vltor mur....

for 138.00

I dont think I will ever buy a standard mil-spec receiver after having this one....

oh and the coating is even better.... its sateen like teflon but confirmed its just a better than mil-spec anodizing....

When did you purchase the SD upper? I know when those SD uppers first came out, they were supposed to be used in conjuction with their lower only as the tolerances were machined tighter. I had an SD lower when they first came out and it was as you said, tight fitting on all the mil-spec lowers. I had both the SD upper/lower at the time. I don't see them mentioning that anymore, so I was wondering if they may have changed the tolerances to fit on mil-spec lowers "loosely"? I want that tight fit again.