How to Zero a Rifle Scope for 100 Yards

Start Here: The Fast Way I Zero at 100 Yards

I zero a rifle scope for 100 yards by boresighting, shooting a 3-shot group at 25 yards to get on paper, then shooting 3-shot groups at 100 and adjusting only off the group center until the group is dead on.

If you chase single bullet holes and twist knobs after every shot, you will waste ammo and you will not know what your rifle really does.

Back in November 1998 in Iron County, Missouri, I killed my first deer with a borrowed rifle and a scope I did not trust.

I hit that 8-point buck, but I remember thinking, “I have no clue where this thing really hits.”

Now I hunt 30 plus days a year, mostly bow, but rifle season still matters for my freezer and my kids.

I split time between a 65-acre lease in Pike County, Illinois and public land in the Missouri Ozarks, so my zero has to hold up in wind, cold, and rushed parking-lot setups.

Decide What “Zero at 100” Means for Your Hunting

You need to decide if you want a true 100-yard dead-on zero, or a “dead-on at 100 but a touch high” zero for a little extra reach.

I keep it simple for whitetails and kids, and I run a true 100-yard zero with most rifles.

If you are hunting tight timber in the Missouri Ozarks, forget about trying to stretch your point-blank range and focus on a clean 100-yard zero you can trust at 30 yards.

If you are hunting open edges in southern Iowa or big picked corn around Pike County, Illinois, I can see the argument for 1.5 inches high at 100 if you actually practice at 200.

My buddy swears by a 200-yard zero for everything, but I have found most missed and wounded deer come from people guessing holdover they never practiced.

This connects to what I wrote about where to shoot a deer to drop it in its tracks because the best shot in the world does not matter if your rifle is printing 4 inches left.

Mistake to Avoid: Changing Ammo After You Zero

I learned the hard way that “a box of ammo is a box of ammo” is not true.

Back in 2007 in the Missouri Ozarks, I sighted in with one load, grabbed a different box on sale, and then I wondered why my point of impact moved like magic.

Pick one exact load and stick with it, including bullet weight, brand, and even lot number if you can.

If you want a simple deer load that usually shoots in a lot of rifles, I have had good luck with Federal Power-Shok 150 grain soft points in .308 and .30-06, but you still have to test your gun.

Also decide if you are zeroing for cold weather, because a rifle that groups at 72 degrees can shift a bit at 18 degrees.

Back in Buffalo County, Wisconsin, I watched a guy miss high twice in snow because he sighted in during a warm October afternoon and never checked again.

Here Is What I Do Before I Fire a Shot

I put the rifle in a solid rest, and I do not “sandbag” the barrel.

I rest the fore-end on a bag or a lead sled, and I support the butt with a rear bag so the rifle settles the same every shot.

I check every scope ring and base screw with a torque wrench if I have one.

If you do not have one, snug is not a measurement, and that is how scopes slip and groups “mysteriously” open up.

I wasted money on $400 ozone scent control that made zero difference, but I will spend $45 on a Wheeler FAT Wrench because loose screws will wreck your season.

If you want to understand why deer still bust people even with gimmicks, read my take on are deer smart because their nose and patterning beats most “miracle” products.

Tradeoff: Boresight at Home or Burn Ammo at the Range

You can boresight by pulling the bolt and looking down the bore, or you can use a cheap laser boresighter.

The tradeoff is time versus precision, because boresight only gets you close, not zeroed.

Here is what I do with a bolt gun.

I pull the bolt, set the rifle solid, center the bore on a 1-inch dot at 25 yards, then I adjust the scope until the crosshair sits on the same dot.

With some rifles you cannot look through the bore, so I use a laser boresighter and accept that it is “close enough” to get on paper.

I have used the Sightmark Laser Boresight in .30 caliber, and it got me on paper fast, but the batteries died if I left them in it all season.

It is a tool, not magic, and you still shoot groups to confirm.

Get on Paper at 25 Yards Without Wasting Your Day

Your first goal is not a perfect bullseye.

Your first goal is making sure you hit the paper and you know which direction to move.

Here is what I do at 25 yards.

I shoot one careful shot at a big target with a 3-inch orange dot, then I measure how far the hole is from the dot.

If I am more than 3 inches off at 25, I stop and check mounts and rest again because something is wrong.

Most scopes adjust in 1/4 MOA clicks, which is about 1/4 inch at 100 yards.

That means one click is about 1/16 inch at 25 yards, so do not overthink the math.

At 25, I move the group in the direction I want it to go, and I get it close to center, then I move to 100.

If you want a simple mental shortcut, 4 clicks is about 1 inch at 100, and 16 clicks is about 4 inches at 100.

Mistake to Avoid: Adjusting After Every Shot at 100

I learned the hard way that a single shot is a liar.

Back in 2013 on my Pike County, Illinois lease, I kept twisting turrets after every shot and I ended up chasing my own flinch.

At 100 yards, shoot a 3-shot group, let the barrel cool, then adjust.

If you cannot shoot a 3-shot group under about 2.5 inches with a hunting rifle off bags, slow down and fix the shooter first.

Most “bad rifles” are a bad rest, a bad trigger press, or a guy trying to sight in while drinking gas station coffee and shaking.

This ties into how fast can deer run

My Quick Rule of Thumb

If your first shot at 25 yards is not on paper, do not keep firing, and boresight again before you waste a whole box.

If you see a tight 3-shot group that is 3 inches right at 100 yards, expect your scope is fine and you just need to dial 12 clicks left.

If conditions change to a 15 mph crosswind or your barrel is too hot to touch, switch to slow groups with cool-down time and confirm again before you call it zero.

How I Make Scope Adjustments That Actually Stick

I tap the turret caps with my knuckle after adjustments because some scopes do not settle right away.

Then I shoot another 3-shot group to confirm, not to “make myself feel better.”

If your scope has a zero stop or resettable turrets, set them after you are truly done.

I do not set anything until I have two groups in a row that agree.

Two groups that overlap tell the truth.

One pretty group can be luck.

Tradeoff: Dead Center at 100 or Slightly High for Real-World Holds

If you want dead simple holds, put it dead center at 100 and call it good.

That is what I do for my kids and for most Midwest deer hunting.

If you insist on the “1.5 inches high at 100” plan, you better prove it at 200 on paper, not in your head.

In southern Iowa field edges, I have seen 180-yard shots that felt like 90 because the deer was calm and the rest was solid.

In the Missouri Ozarks, that same shot can be through brush you did not see, and then your “flat shooting” plan turns into a long night.

Confirm at 200 Yards So You Stop Guessing

I do not care if you only plan to shoot 100.

I still want you to shoot one group at 200 so you know what your drop looks like with your eyes.

Here is what I do.

I keep the same point of aim, shoot 3 shots at 200, and I write the drop on a piece of tape on the stock.

If the drop is 6 inches and you cannot hold that steady, then you just learned your limit for this season.

This connects to how much does a deer weigh

Mistake to Avoid: Zeroing Off a Bench and Then Shooting Offhand All Season

I have watched guys shoot bugholes off the bench and then miss a standing doe at 70 yards.

The bench is for zeroing, not for proving you can hunt.

After I confirm zero, I shoot 3 rounds from kneeling, sitting, and standing with sticks.

I use the same sling, same coat, and same gloves I will hunt with.

Back in the Upper Peninsula Michigan, bulky gloves changed my trigger feel so much that I started jerking shots until I practiced with them.

What Gear I Actually Use, and What I Quit Buying

I burned money on gear that did not work before I learned what matters.

For sight-in, what matters is a stable rest, a clear target, and a scope that holds zero.

I like Caldwell DeadShot bags because they do not slide around, and they cost about $35 to $45 last time I bought them.

I have used the same front bag for years, and it is still not leaking, even after being tossed in my garage next to deer processing tables.

For targets, I use Shoot-N-C style splatter targets because I can see hits without walking every shot.

That saves time, and it keeps my barrel from overheating while I jog back and forth like an idiot.

I wasted money on “tactical” paper targets that looked cool and did nothing for my groups.

Decide How You Will Handle Cold-Barrel Versus Warm-Barrel Shots

Most deer get shot with a cold barrel.

So I care where the first shot goes, not just the third.

Here is what I do.

I fire one cold shot at 100 at the start of the session, then I do my groups, and I fire another cold shot at the end after a long break.

If the cold shot is off by 2 inches, I pay attention because that is a real hunting problem.

Back in November 2019 in Pike County, Illinois, I killed my biggest buck, a 156-inch typical, on a cold-front morning sit.

That shot did not care what my rifle did on shot number five.

Tradeoff: High Magnification for Tiny Groups Versus Real Hunting Sight Picture

I see guys crank a scope to 12x to sight in and then never touch it again.

That is fine until a buck shows up at 40 yards and your scope is a soda straw.

I sight in at the magnification I plan to hunt with, usually 4x to 6x in the woods.

If I have a variable scope, I confirm at both low and high power because some cheaper scopes shift a bit.

I am not saying you need a $1,800 scope, but I am saying cheap glass can cost you a deer.

Mistake to Avoid: Ignoring Wind at the Range

Wind will lie to you, especially at 100 if you are shooting lighter bullets.

If you have a steady 12 mph crosswind, your group might be tight but drifted, and you might “zero” to the wind by accident.

Here is what I do.

If the wind is steady, I still zero, but I write down the wind direction and speed, then I confirm again on a calmer day if I can.

If the wind is switching, I stop trying to be perfect and I focus on getting a reliable center hit, then I come back.

This connects to what I wrote about do deer move in the wind

How I Teach Kids to Zero Without Building Bad Habits

I take two kids hunting now, and I do not let them sight in by themselves.

I sit next to them, load one round at a time, and I talk them through one clean shot.

I start them on a .243 or a soft .350 Legend setup in straight-wall areas like parts of Ohio, because recoil makes flinches fast.

If you are building a new hunter, forget about “magnum pride” and focus on a rifle they can shoot 20 rounds without fear.

I also keep the sessions short, like 12 to 18 rounds total, because tired kids start yanking triggers.

When they make a good shot, I stop and let that be the last thing they remember.

Where People Get Hurt: Rushed Tracking Because They Don’t Trust Their Zero

Bad zeros create bad decisions after the shot.

I learned the hard way that pushing a deer too early can ruin your chance to recover it.

In 2007 I gut shot a doe, pushed her too early, never found her, and I still think about it.

Part of that mistake was me not having total confidence in my setup and rushing the whole process.

If you want to stack the odds after the shot, read what I do in how to field dress a deer

FAQ

How many shots does it take to zero a rifle at 100 yards?

I can usually do it in 9 to 15 shots if the scope is mounted right and I am not fighting wind.

If you are burning 30 rounds, you are probably adjusting after every shot or your mounts are loose.

Should I sight in at 25 yards first or go straight to 100?

I start at 25 any time the scope was removed, the rifle got bumped hard, or it is a new setup.

It saves ammo and it saves pride because missing the whole target at 100 is a dumb feeling.

Why is my rifle shooting a wide group even after I adjust the scope?

A wide group is usually the rest, the shooter, or loose hardware, not “the scope being off.”

I check ring screws, base screws, and then I slow down and let the barrel cool.

Where should my bullets hit at 100 yards for whitetail deer?

I set it dead on at 100 for most whitetail hunting because my holds stay simple inside 200.

This pairs well with my shot placement notes in where to shoot a deer to drop it in its tracks

How often should I re-check my zero during deer season?

I check it once before season, once after any hard fall or scope bump, and once mid-season if I am traveling.

Going from Pike County, Illinois to the Missouri Ozarks in the same season, I confirm zero because gear gets bounced around.

Can I trust one perfect group and call it good?

I do not, because one group can be luck and one flyer can be you, not the rifle.

I want two groups that agree, and I want at least one cold-bore shot that matches them.

When I am trying to time deer movement after I confirm zero, I check feeding times first.

When I am setting expectations for how deer react after the shot, I think about how fast can deer run

When new hunters ask me basic deer terms at the range, I send them to what is a male deer calledwhat is a female deer called

When I am picking stand spots after rain, this ties into where do deer go when it rains

My Last Check Before I Put the Rifle Away

Before I leave the range, I shoot one last 1-shot “confidence check” at 100 yards from a cold-ish barrel.

If that last shot lands with the rest of my group, I stop messing with it and I go hunting.

Here is what I do before that last shot.

I snug the turret caps, I mark my turret position with a silver Sharpie line, and I make sure my scope isn’t creeping in the rings.

I also write my load on a piece of tape on the stock, like “.308, 150 Power-Shok,” so I do not grab the wrong box in the dark.

I learned the hard way that “I’ll remember” is how you end up with three different partial boxes rolling around the truck floor.

Tradeoff: Keep Chasing Perfection, or Lock In a Repeatable Zero

There is always a way to make a group a half inch tighter if you keep burning ammo.

The tradeoff is you can also burn your confidence right along with it.

For deer hunting, I care about repeatable hits in an 8-inch vital zone, not Instagram groups.

If your rifle is stacking 3 shots into 1.75 inches at 100 and the group is centered, that is a dead deer out to sane ranges.

Back in Buffalo County, Wisconsin, I watched a guy chase a perfect cloverleaf for an hour and leave with a hot barrel and a worse zero than he started with.

He would have been better off locking it in, going home, and practicing field positions.

Here Is What I Do to Keep a Zero Through the Season

I keep the rifle in a case when it rides in the truck, and I do not toss it behind the seat like a shovel.

I also do a quick “bump check” after any fall, even if it is just one shot at 50 or 100.

Here is my routine that has saved me more than once.

I re-check ring and base screws after the first 10 to 15 rounds on a fresh mount job, because things settle.

If I am traveling, I confirm zero the day I arrive if I can.

Going from Pike County, Illinois to the Missouri Ozarks, rifles get bounced on gravel roads and dragged in and out of side-by-sides.

I do not care what the internet says about “quality optics never shift.”

I have seen expensive scopes get knocked off from one dumb drop onto a tailgate.

Mistake to Avoid: Forgetting Your Scope Height and Shooting Over a Deer at 20 Yards

This one bites new rifle hunters every year, and it is not their fault.

Your scope sits 1.5 to 2 inches above the bore, and at close range you will hit low if you aim “perfect.”

Here is what I do to fix that.

After I zero at 100, I shoot one round at 25 and one round at 50, using the same point of aim.

Then I know exactly how low I hit up close, and I do not have to guess on a doe at 18 yards in thick Ozark timber.

If you are hunting tight cover, forget about dialing turrets and focus on knowing your 25-yard impact and making a calm shot.

What I Want You Thinking About on Opening Morning

I want you thinking about the wind, your entry, and your shot angle, not your zero.

A rifle that you trust makes you slower in a good way.

You pick a spot, you press the trigger, and you watch what happens.

That confidence is earned at the range, not talked into existence in the stand.

Back in November 2019 in Pike County, Illinois, that 156-inch buck stepped out after a cold front and I never once thought about my scope.

I only thought about hair, shoulder line, and a clean squeeze.

If your zero is solid, your brain has room for the stuff that actually kills deer.

One Last Money Tip From a Guy Who Has Wasted Plenty

I am not a pro staff guy, and I am not trying to sell you a “system.”

I am telling you what has kept me from screwing up seasons.

If you are going to spend money anywhere, spend it on solid mounts and a decent rest.

I have had better luck with boring stuff like quality rings than I ever did with gimmicks like ozone machines.

I wasted money on $400 ozone scent control that made zero difference, but a $45 torque wrench and decent rings have saved me multiple years.

Leave the Range With a Simple Plan

Your rifle should be centered at 100, verified at 200, and checked at 25 or 50 so close shots do not surprise you.

If you do that, you are ahead of most guys on the firing line.

Then go shoot from kneeling and sticks, because that is how deer season really happens.

After that, quit touching the turrets unless something actually changes.

Trust your zero, hunt smart, and put meat in the garage.