Awhile back I thought I knew everything and decided to blog about it. Case in point: what distance to zero your 300 Blackout (BLK) rifle. Quite a bit of what is written there makes send and is pragmatic. However as I have grown into my kit and decided what works and doesn’t work well a new approach has taken shape- and it’s worth sharing.
Let’s refer back to this handy trajectory chart for common 300 BLK loads:
Although I enjoy shooting subsonic rounds out of my BLK it’s cheaper and more enjoyable to fire supersonics when you’re at a range and your buddy is firing his 5.56. So for a supersonic zero I have changed to a 25/150 yard – as illustrated by the red line above. This leaves me dead on at 25 yds, about 2″ high at both 50 and 100 yds, back on zero at 150 yds and 5″ low at 200 yds. That’s not too much to remember and even without doping shots hits will deviate by about 2″ or less at any range from 0-250 yds.
Now to compare the blue line to represent subsonic rounds to the red line- big trajectory difference as one would expect. Figuring out holdover on the fly (and without a dual-reticle optic) is a nonstarter in this case. For the subsonic zero range: 10/100 yard zero. That setting leaves me 2″ high at 25 yds, 3″high at 50 yds, back to 2″ at 75 yds and zero at 100 yds. Again this not much to remember and 2″-3″ is not a lot of deviation without doping.
The sighting system I’m using now is flip-up BUIS for supersonics and my Aimpoint T1 for subsonics. If you take that approach make sure to use a rear sight with a narrow aperture so you can see through the optic and stay on the sight plane. My Troy di-optic rear site proved to be too wide for that task so it has returned to the interwebs from whence it came and I replaced it with a KAC. If you ever switch to BUIS and don’t remove your optic be wary of that problem- It stumped me when I sabotaged a range outing that way.