300 BLK SBR - what is your zero?

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just_me_mongo
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300 BLK SBR - what is your zero?

Post by just_me_mongo »

Howdy,

I want to try hunting this year with my .300blk SBR. 762 can by Silencer CO. My handload is 1050fps.

Are you guys zeroing at 50 yds, 100yds, or something else?

I zeroed my sbr @ 50 yds. I noticed that the front sight post was deep down there. May not be enough for 100 (but I havn't tested it yet).

I was wondering if a 100 yd zero is a bit too far...

All advice welcome!

Thanks.
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plant.one
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Re: 300 BLK SBR - what is your zero?

Post by plant.one »

knowing what bullet you're using will help as the BC is important.


but generally speaking - if memory serves correctly - a hunting zero of 75 yds gives a +/- of approx 3" from like... 25 yds to 100 yds. with certain projectiles anyway.


dont hold me to that - without more data about YOUR setup i cant be accurate with that estimate - plug your data into a ballistic calc like hornady's and see what it comes up with the best trajectory for YOUR projectile and YOUR firearm (sight height is important!)




https://www.hornady.com/team-hornady/ba ... lculators/#!/




this for example is the sub-x @ 1050 (16" barrel) with a 100 yd zero with a 2.5" sight height

Range Velocity Energy Trajectory Come Up (MOA)
0 1050 465.0 -2.5
25 1036 453.0 1.2
50 1022 441.0 2.9
75 1010 430.0 2.5
100 998 420.0 0.0

this is a 75 yd zero

Range Velocity Energy Trajectory Come Up (MOA)
0 1050 465.0 -2.5
25 1036 453.0 0.4
50 1022 441.0 1.2
75 1010 430.0 0.0
100 998 420.0 -3.3


either of thes will give you a MPBR (point and shoot, no elevation adjustment necessary) for a vitals shot on a deer out to roughly 100 yds. however as you can see, the 75 gives a flatter curve in the front 3/4 of that shooting range.

i strongly suggest you go read GDS's primer on subsonic hunting to brush up on when/where its approiate to use this kind of velocity levels for hunting as well.

viewtopic.php?f=145&t=87186

and please remember - knowing your range and your ability to have good shot placement are going to be absolutely critical to your success, so if you dont have one already, you should consider a good rangefinder, or know your shoting distances at your hunting spot very closely. and then spend time practicing. as much as you can reasonably afford to with the projectile you have chosen to hunt with.


HTH
Reloading info shared is based on experiences w/ my guns. Be safe and work up your loads from published data. Web data may not be accurate/safe.
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Dr.Phil
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Re: 300 BLK SBR - what is your zero?

Post by Dr.Phil »

As previously stated, determine the round that you intend to use.
Unlike most other cartridges, 300 BLK has a HUGE swing in trajectories.

Start with reading up on Point Blank Zero:
https://www.everydaymarksman.co/marksma ... lank-zero/

Here is a calc to help:
http://www.shooterscalculator.com/point-blank-range.php

I personally use a 100 yard zero for supers and dial up 15 MOA to adjust for Subs.
viewtopic.php?f=128&t=91066
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TRshootem
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Re: 300 BLK SBR - what is your zero?

Post by TRshootem »

Thanks Dr. Phil for that reminder, especially for some of the newer guys here. I certainly found your info useful, including 55 gr SP .223 subs in a RARR. One revolution up from my super zero put these TiteGroup powered subs on a 2" plate at 100 yds. The gal friend was stunned at how quiet the suppressed rifle was and the accuracy.

In the 300 BLK loads, depending on the bullet and velocity, the 11-12" dial up gets things as described. Thanks again for a timely post.

TR
gnfiter3
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Re: 300 BLK SBR - what is your zero?

Post by gnfiter3 »

I looked at this several times and came to a 50 yard zero. It appears my 10.5 inch pistol barrel from Rosco, is better than the unknown 16 inch from a different upper. 50 yard zero is just a bit tighter at 100 than the 16 inch.
The 10.5 is for HD, and I found the POI with a 50 yard zero to be a few inches low at 30 feet.
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wildfowler
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Re: 300 BLK SBR - what is your zero?

Post by wildfowler »

There’s really not a big difference on paper even though the BC can be significantly different when using a 220 grain bullet at subsonic muzzle velocity. Specifically I’m referring to the difference between the 220 Sierra match king or the 220 Sierra round nose in my example.

As others have stated, the ballistic calculators are going to help you make your own determination based on what your objective is. What I do is run the numbers using different zeros then screenshot them so that I can scroll back-and-forth quickly and do a quick comparison.

For me personally, my sub sonic shots generally will not exceed 100 yards and normally or 50 yards or less. So for me a 50 yard zero is paramount.

A 100 yard zero puts me 3” high at 50-70 yards with either bullet.

A 50 yard zero puts me basically dead on with either bullet between 25-50 yards and is still less than 2” low out to 75 yards which for all practical purposes is still a dead armadillo but could I miss high at the same distance with the 100 yard zero.

Conversely, folks who shoot subsonic at longer ranges will take notice that the amount of bullet drop is approx 12” greater if using a 50 yard zero than if using a 100 zero at 200 yards.

I don’t have anyway to post pictures anymore but it literally took me less than four minutes to generate five BC reports. I then edited the screenshot and added some text like SMK/50 or RN/100 so I would know what I was looking at. Scrolling back-and-forth quickly I can absorb a large amount of data very quickly and it becomes very easy to see the difference. Depending on your objective the differences or significant.

Edit: it’s never a bad idea to shoot on paper at various distances to confirm what the calculators tell you. For your own piece of mind.
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