zeroing a 308 rifle with iron sights.

I’ve come into a bit of a pickle about Zeroing my rifle I already use a 36 yard zero on my AR’s and it works great on both the SBR and the standard 16 in Barrel. The only catch is these are done in 5 5 6, so the next question is whether or not this zero will hold with a throw a platform.

I am currently using a 18in barrel 308 from Aero Precision and a custom assembled 12.5 sBR for the shorter version. Does the ballistic drop chart for the 36-yard 0 on a aR-15 line up with the 308 version. Example when doing a ballistic drop test you can see the round impact in a tight group pattern.

Would the 308 be a tighter grouping smaller than 5 in or compared to a CD or would it be a more wider spread

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I’ll take a stab at it. I assume you want the .308 to hit @ point of aim @100 yards and you have access to a 100 yard range. Zero the .308 @ 25 or 35, it doesn’t matter. Next step. Take a shot at 100 yards. If you’re on the paper, adjust the sights and shoot again. If you’re not on paper, get a bigger piece of paper. Repeat the process until you hit @ point of aim. The size of your groups will depend on the rifle, the ammunition and you.
“That’s all I have to say about that”
F. Gump

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thanks for responding to my post. I’m going to post a video of what I’m trying to portray.

the question is what is the spread on various targets at known ranges.

If you watch the video its the spread of the 36 yard zero that i like and compared to my time in the army 25/300. would this line up on 308 or would it be tighter of from 0-300.

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This threw me off. A group is the total bullet spread, horizontal and vertical, at a given range.(my interpretation) I watched the video and now I understand what you’re asking.

.223 and .308 have similar bullet drop, up to a point. Of course it depends on the ammunition that is used.
Damn, I wasted a perfectly good tutorial on how to sight in a rifle.:smile:

“That’s all I have to say about that”

                 F. Gump
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It was a well done tutorial by the way. Have you shot ar10 with irons pass 300 by chance?

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yes
but that was 30 odd years ago

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I zerod my 308’s with iron sights at 50 yards. if I shot them at 300 the target would have to be a 4x6 sheet of plywood.:rofl:

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@58marine @srdiver @Belt-Fed There has to be someone on here that does video of running a 308 from 50 to 400 with irons. I think its something that is not touch on in the gun community. The AR15 and 556/223 is like a god and every other caliber is left to the side line. I think its a lost art with shooting caliber other than 223/556 with iron sights.

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use to do it on a regular basis with a FN or G3 most of the time out to 600m and at least 3 times a year to 1000m with the FN

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There are several “double barrel” members here from 308AR.com

Perhaps one of them will chime in soon -or be able to point you in a direction this info can be found.

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No. M16a1 out to 500 meters is the closest . Check this ballistic calculator out. Might help.

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lets see

@Ambassadors

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Playing with the calculator is more fun than doing yard work, so…
150 gr. bullet, b.c. of .408, m.v. of 2820 f/s,
sights 2.5" above bore center, zeroed at 36 yards.
25 yards, .7" low
150 yards, 3.7" high ( highest part of trajectory)
300 yards, 2.8" low
About 6.5" vertical spread.

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For doing any kind of ballistic calculations, I use a great app called Bullet Drop. It is available free for IOS if you run an Apple product.

This is great for plug and play calculations as long as you can input the variables.

I use this routinely to figure out what range I need to zero my rifles at in order to have a bullet traveling within a 4-6” Circle from 0-300 yards (if the ballistics of that round permit it)

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I’ll get into this stuff tonight. I’m running my .308 Win 150gr handloads at 2600 fps from an 18" barrel. Hornadr FMJ-BTs. All my 150 loads are just range ammo, and get shot across all the .308s when I’m out there. It’s my go-to load just to shoot.

For a 5" vital zone, it gives me a Maximum Point Blank Range of 321 yards, but that needs to be with a 274-yard zero on the gun. If I accomplish that 274-yard zero, everything from the muzzle, to 321 yards, never leaves a 5" point of impact. That just means I hold centermass on everything out to 321 yards, and I’m good within 5" of where my sights are.

I use JBM Ballistics “Trajectory” calculator to come up with this stuff. Here’s the chart I came up with:

Fire off any questions you have. I’ll be here all night, so kick back and relax, enjoy the music, and remember to tip your server… :stuck_out_tongue_winking_eye:

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I’m just happy there is one to tip, was worried they all spit

oops, split

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The man in the know has arrived.:+1:

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Let’s look at that chart more, and check out the drops at different distances. I need a 274-yard zero. at 250 tards, it’s 8.0" of drop (with 100-yd zero). At 300 yards, it’s 14.3" of drop. If I divide that between the two, for 275 yards (close enough), that’s around 11"~12" of drop, at 275. Not other shorter distance has that kind of drop. So, how do you accomplish that…

Change the data in your chart. Go back, and change to a 274-yard zero, and find out what you get for data. Here’s what that gave me:

^^^ That’s a 274 yard zero that I can do at a shorter distance - with the drop numbers. If I zero that gun 1.4" high at 50 yards - that’s a 274 zero. Or, I can zero it 3.9" high at 100 yards - 274 zero.

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I’ve got a 13.5" barrel .308AR, with a pinned brake on it - barely over 16" of barrel length. I know that thing is right on the money inside of 300 yards - point, shoot, hit - with red dot. I’ve stretched it to 400 holding a little high, (head high over the IPSC target gets hits on steel), but I never payed attention to where it was hitting. The target gave me “hit” feedback, so I was good with it. I’ll take it out next weekend at hundred yard increments on IPSC steel, and see what it does, and get feedback in here. That should help, with honest target pics of the impacts.

This is the little hooker, right here:

https://forum.308ar.com/uploads/monthly_2018_07/P1060432.thumb.JPG.2915f48b776c2ef48b9e464a91c7cf60.JPG

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Shiit, that didn’t work. Here it is:

13-5%20308ar

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