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.300 ACC BLK, 16" barrel, 1:8 twist shooting, REM UMC 220gr OTFB & REM UMC 120gr OTFB at 50 yards.
Zero'd with 120gr and when I shoot the 220gr the drop is 3" at 50yards. I realize it is a heavier bullet, but why 3" at 50 yards.
Just doesn't make sense to this OldMan
220's are only doing around 1000fps, less than half of the 120's.
Never used a ballistic calculator (forgot site), until I built and used my 10" 300 BLK AR for the first time. Zero'd at 100 and spent a day at the range playing with different subsonic loads hitting plates at 100. Moved to smaller plate at 150 and all misses. Just had to stop and run the calculator for zero and drop for each range 25-150 yards. Eye opening, had read about 300BLK, had researched 300BLK, but over 10" drop at 150 with 100 yard zero was eye opening. But quiet.
The notion of "subs to supers with a simple magazine change" is overstated, unless you're willing to carefully evaluate your loads and zeros, and make certain compromises. (Or if you only shoot the subs at close range, or don't care where they hit)
I only use both subs and supers in one rifle. (All my other 300blk's have a single, dedicated load)
It's zeroed for supers (115 grain at 2145fps)at 50y, and my subs (168 grain at 950fos) impact ~7" low at 100.
http://i1121.photobucket.com/albums/...CB545DA6A.jpeg
http://i1121.photobucket.com/albums/...D6D8B58FE.jpeg
The 50 yard zero is not my preference, but to make both loads work ok, it was a compromise.
This combination of subs and supers works ok in my 10.5" (with my handloads) but goes to €ге% in my 16", as the 16" throws the subs several inches left, in addition to even more drop (~10") due to thin barrel profile + suppressor mount timing.
(Edit: yes, subs drop like a rock)
I ran some Remington 220 subs through my chronograph. 12.5 in barrel some were supers... This data makes no sense to me either. I would try something else to see if it performs better for you.
Average: 1698.3 FPS
SD: 587.8 FPS
Min: 897 FPS
Max: 2110 FPS
Spread: 1213 FPS
Shot/sec: 0.1
True MV: 1699 FPS