Usable but challenging - TRYBE Defense AR-15 Ultra Lightweight Magnesium Alloy Stripped Upper Receiver

i have two FDEs and one black and every one of them is different the first fde was loose as a goose and the barrel pocket and the pins were sloppy . had to be swapped around several lowers to find a reasonable fit that or use one of those rubber upper slack killer things. the second fde was much tighter in the pins and just right in the barrel pocket. the black one was tight in the pins but just right in the barrel pocket. all usable but just a shade off here or there -- i do like the light weight and that they match the trybe handguards and fit those perfectly. i would say that these uppers are more for "experienced" builders that know how to make up for things being a few thou off here or there -- like "gunsmith fit" sort of deal