Quoted:
Hey guys, I know nothing about 9mm uppers, but have an extra sbr'd standard lower and a yhm cobra 9 can laying around. Which upper would you buy? Will my can fit under the 4" palmetto rail? I cannot find the thread pitch listed for the foxtrot. Is it 1/2x28? Do they all have last round bolt hold open? Also looking at endo mags... Opinions? Also, any other brands I should consider for a cheap 9mm?? Thanks!
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I went down this road a while back...had a spare SBR'd lower, just like you do. After messing with 9mm uppers, I just bought an MP5.
All those uppers are basically the same...just buy whichever one you like the looks of best. That Foxtrot Mike upper is the best deal...I'd go with that one. Foxtrot Mike barrels are threaded 1/2x36.
The internal diameter of the hand guards is pretty small...if I remember correctly the ID of the PSA upper I had was 1.3"...too small for most 9mm suppressors. Foxtrot Mike's FAQ page says they are 1.3" in diameter.
LRBHO usually depends on the lower you are using. I know you won't lock the bolt back with ENDO mags. Maybe there is some glock mag adapter that will, I don't know.
ENDO mags are pretty cool, that's what I used in my PSA upper. No LRBHO with ENDO mags. Also, the ejector is built into the magazine...so if you following correct clearing procedures, like during a match or competition, you drop the mag first, then clear the chamber...but since the mag has the ejector, you have to hold or lock the bolt back, then reach in with your finger to push the round out of the bolt face. Not a deal breaker for me, just something to be aware of.