300 blk zero assistance

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

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Yosemite91
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300 blk zero assistance

Post by Yosemite91 » Sun Oct 24, 2021 11:04 am

Hey all new here. I recently got my first 300 with a 10.5” barrel. Im looking to zero it but I’m limited to 25yards currently. Does anyone know of a general POA at that distance to give me a decent zero at both close and distant ranges. I’ve read of a 36 yd zero that will land in a dvd out to 200. Any advice would be awesome thanks!

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der Teufel
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Re: 300 blk zero assistance

Post by der Teufel » Sun Oct 24, 2021 2:07 pm

Not directly answering your question, but it depends upon the ballistics of the round you're using.
That is, a 150 grain bullet with a muzzle velocity of 1800 fps will drop faster than a 110 grain bullet with a muzzle velocity of 2400 fps.
Both will drop less than a subsonic 220 grain round.

What are you shooting?
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ReadyAimDuck
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Re: 300 blk zero assistance

Post by ReadyAimDuck » Sun Oct 24, 2021 2:59 pm

As stated above it is going to depend upon the bullet/velocity that you are using. I would suggest that you take the ballistic data of the load that you are using and then use a couple of simple calculators that will give you a good idea of trajectory based on that load.

I like to zero for maximum point blank range. For example, one 110 gr. supersonic load I use will remain within 6" out to 238 yards if zero'd at 35 yards (second zero is at 206). I found the basis for this using the maximum point blank range calculator in the top link below. What i would do, if i wanted these results but only had a 25 yard range, would be to then look at the balistic calculator in the bottom link below and zero the optic accordingly. So, this 35 yard zero that I have shows that it would be .71" low at 25 yards. I would try to sight the rifle in to be as close to .71" low at 25 yards as possible, and this would give me the approximate 35 yard zero with a maximum point blank range of 238 yards. Give or take. It should get you close, anyway.

https://shooterscalculator.com/point-bl ... =2.75&ts=6

https://shooterscalculator.com/ballisti ... eate+Graph+

Yosemite91
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Re: 300 blk zero assistance

Post by Yosemite91 » Sun Oct 24, 2021 9:01 pm

Thanks for the replies! I’m probably going to stay with a 110gr given the research. Eventually I would like to make the move to subsonic but that’s no time soon. Still new to this round so I’m not sure about all the different options and routes to take. I’m sure there’s another thread on here discussing those topics though

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bangbangping
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Re: 300 blk zero assistance

Post by bangbangping » Sun Oct 24, 2021 9:50 pm

Assuming you're somewhere around 2200 fps with a 110 grain bullet in a 10" barrel...sight in dead on at 25 and you shouldn't be more than two or three inches high or low out to 200. That said, always verify at any range you plan to hunt.

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dellet
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Re: 300 blk zero assistance

Post by dellet » Mon Oct 25, 2021 11:30 am

As easy as this sounds, it gets very tricky. Getting on paper at 200 this will work fine. Making a kill shot at 200 based on a 25 yard zero is risky at best.

1/4" difference at 25 yards makes about 1" difference at 100, and 2" at 200. So unless you are shooting a true one hole group at 25 yards, the difference at 200 will be sizable.

Where I shoot, a 110 Vmax, 2200 fps

25 yard zero
100 yards = +1.5"
200 yards = -4.9"

.308" high at 25 yards
100 yards = +2.7"
200 yards = -2.4"

.308" Low at 25 yards
100 yards = +.3"
200 yards = -7.3"

For a bullets width difference, that could be a game changer.
edit to ad low at 25 yards
300 Blackout, not just for sub-sonics.

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bangbangping
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Re: 300 blk zero assistance

Post by bangbangping » Wed Oct 27, 2021 9:45 am

dellet wrote:
Mon Oct 25, 2021 11:30 am
As easy as this sounds, it gets very tricky. Getting on paper at 200 this will work fine. Making a kill shot at 200 based on a 25 yard zero is risky at best.

1/4" difference at 25 yards makes about 1" difference at 100, and 2" at 200. So unless you are shooting a true one hole group at 25 yards, the difference at 200 will be sizable.

Where I shoot, a 110 Vmax, 2200 fps

25 yard zero
100 yards = +1.5"
200 yards = -4.9"

.308" high at 25 yards
100 yards = +2.7"
200 yards = -2.4"

.308" Low at 25 yards
100 yards = +.3"
200 yards = -7.3"

For a bullets width difference, that could be a game changer.
edit to ad low at 25 yards
Yup. Sight height above bore can be huge, too. When sighting in at 25, a 1/2" difference in sight height could be nearly 4" difference in 200 yard impact.

"Sight in at (close) X and you'll be on at (far) Y" is never more than a rough estimate.

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