I need to re-sight-in an AR15 with a red dot and an AR10 with a scope. I have a Harris bipod I can attach to both and I also have a Caldwell shooting rest. Which would you use to sight them in with?

Thanks!

Bipod and a rear bag is what I use.

Get a rough boresight by removing the BCG and looking down the barrel, zeroing the optic on that.

Then shoot at 25, adjust to where it should hit for your desired zero range (from a ballistic calculator), then kick it to the desired zero range (100 is my preferred), make final adjustments on target.

thread.

Ive had better luck with the bipod/rear bag setup

quote:

Originally posted by matai:
I need to re-sight-in an AR15 with a red dot and an AR10 with a scope. I have a Harris bipod I can attach to both and I also have a Caldwell shooting rest. Which would you use to sight them in with?

Thanks!

Do they have free-float handguards? If yes, then bipod is fine. If no, beanbag is better.

I second RHINOWSO's comments. I often shoot prone with a bipod, therefore I'm confident in the results.

But go with the support method with which you can produce the most consistent accuracy. Rough bore sighting, then a target at 25 yards is a proven method. Depending on you ultimate zero distance and optics-over-bore height, you're probably looking at point of impact being 1-2 inches low at 25 yards. That should get you close enough to obtain the true zero at your preferred distance.

Here is a chart showing the trajectory of a 55gr 5.56 or .223 bullet. As you will see, sighting in at 50 yards you will be good out to around 225 yards.

I also use a bipod with rear sandbags.




Jim

For initial zeroing I use as solid a rest as I can get, front and rear, because anything less steady will leave me wondering if it was me or the gun or something else that affected the groups and the zero. Then if I intend to shoot the gun some other way, such as prone with a bipod, I confirm the zero using that method because sometimes changing the method changes the zero.

quote:

Originally posted by sigfreund:
Then if I intend to shoot the gun some other way, such as prone with a bipod, I confirm the zero using that method because sometimes changing the method changes the zero.

The rifle's zero doesn't change when its relative position to the ground changes. What does change is the shooter, and how the shooter controls the rifle. See the video below from Jacob Bynum, owner of the Rifles Only school in Texas.

shooting positions

quote:

Originally posted by fritz:
What does change is the shooter, and how the shooter controls the rifle.

Yes, of course the rifle doesn’t change, nor does how high it is above the ground when fired affect the zero unless we were shooting at a long distance and at an extreme angle from something like a highly elevated platform.

In my experience, however, when switching from shooting in an upright position with a firm bench rest to lying prone with a bipod resting on different types of surfaces, I sometimes get different points of impact with the same point of aim. I am perfectly willing to accept that that may not be true of all shooters, but I am referring to my experiences, not others’.*

My advice was based on the assumption that other shooters might also find that they get different results between the two methods and they shouldn’t assume otherwise unless they are skilled and experienced enough that they wouldn’t be asking for advice about the question in the first place. I am also more than willing to accept that if one’s POI changes due to change in position and other factors, it may be due to poor technique that should be corrected somehow. Ultimately, however, what matters is where the bullet hits, and therefore the shooter should know if that’s affected by changing his shooting position.

And if the results of one’s shooting are important, I will also therefore continue to offer the advice to confirm points of impact in different positions while admitting that, “Learn how to shoot,” is also good advice.

* The same is evidently true of some professional snipers. Although I cannot cite chapter and verse, I recall reading the same caution in the literature.

At this moment the shooter's name escapes me, but one of the best "across the course" competitors has a slightly different zero when he shoots standing, off-hand, and slung. I recall he adjusts his zero laterally either 1/4 MOA or 1/2 MOA. But if IIRC, that's the only position he makes an adjustment for zero/POI. I haven't heard of other shooters doing this. But this guy is one of the best of the best. IMO he knows he does something in the standing slung position. He's good enough to know he can't fight it. So he adjusts his equipment.

I trained with Nick Irving for 4 or 5 days in a Rifles Only precision rifle course. Nick was a sniper for the Rangers, was deployed with a KAC SR-25 rifle, and has some 33-ish confirmed kills in the sandbox as a sniper. Nick uses the same zero for all positions that he shoots his SR-25. Since our training involved a lot of positional shooting, we thoroughly discussed the topic of a rifle's zero/POI changing with shooting positions. I am thoroughly convinced that if a rifle's POI shifts due to positional changes, the shift is induced by the shooter.

I've trained with Jacob Bynum of Rifles Only a number of times. I was not present with my linked video was produced. However, I've seen Jacob demonstrate the exact things done in that video, to students who believed rifle zeros change from various positions. Jacob has even done it with those students' rifles. Jacob's the real deal. That video is the real deal.

I compete in various rifle and carbine events -- including Precision Rifle Series, National Rifle League, Competition Dynamics, and Whittington Center events. I am around hundreds of talented shooters who do the same. I am not aware of any top competitor who believes their rifles' zeroes change due to shooting positions. However, they do believe that if the shooter's fundamentals are wonky while shooting from non-prone positions, POI will change. But it's not due to the rifle, it's due to the shooter's inconsistent technique.

Yes, I agree that some shooters experience a POI shift when they change shooting positions. I see this frequently with less experienced shooters at matches. Unfortunately, I see it with my own shooting when I'm having a bad day. It's caused by inconsistent or faltering technique.

Bottom line -- when one experiences a POI shift when changing shooting positions, it's due to something the shooter is -- or isn't -- doing while breaking the shot.

Good information that’s an excellent incentive to learn to shoot properly.

I'm not going to make any try at competing with hundreds of talented shooters. But I fully expect that almost all of them are using some sort of magnified optic. I never experience any sort of zero change when I zero a 'scope' and then shoot it in other positions.
But for red dots that is simply not my experience. I get a good zero off the bench and then I try it in more realistic positions. I have no idea the reasons but I have to make adjustments. I'm likely never to shoot a red dot off the bench so I make it go to POA/POI when I'm shooting it offhand. I get that mechanically it is all fine, but you have to do some mental adjustments on the 'dot' and those don't fully translate for me between positions.
FWIW>

I realize I am hopelessly antiquated, but:
I study the ballistic chart for the load I am zeroing and jot it all down on a 3X5 card.
Using that info, I get on paper at 25 yards, using a sandbag rest. Then I confirm and refine at whatever range I think is optimal for the cartridge. Sandbag there, too.
At this point, in the field. I show my age and obsolete technique.
I then judge/estimate range and wind based my 3X5 card info. And then I hold dead on, or over or under and let fly. No turret adjustments, lasing, or ballistic calculators used. No concern given to position. I buy my scopes with the least complicated crosshairs I can to cater to my shooting habits.
I have been known to tape the card to my stock until I can remember cartridge info. While this doesn't often give me tiny groups, it does let me make quick practical accuracy shots at most distances I feel confident at. That how I was taught and I still stick with it.
I often shoot sitting or kneeling using a shooting stick setup I made my myself. Doubles as a walking stick.
And I really like an outdated reticle: German #1. But not many scopes are made with it anymore.

For the last 20 years or so, I have been shooting my rifles almost exclusively from the prone position on a mat; either slung or with a bipod.

I have discovered, to my great dismay, that I absolutely suck when I shoot my rifle from a bench, especially my F-TR match rifle. Something about the size of the rifle, my height (6'4") and the tiny butt benches available at the range. For the life of me, I cannot get comfortable on a bench and the rifle does whatever it wants after I press the trigger. Yuck.

I'd use whatever method you will use to shoot the guns in the future.

quote:

Originally posted by fritz:
I am thoroughly convinced that if a rifle's POI shifts due to positional changes, the shift is induced by the shooter.

Generally, I agree with you, but I have a couple of little quibbles.

I think that different positions, and particularly different ways of supporting the rifle, can change the way the rifle recoils, and thus change where the rifle "wants" its POI to be.

With proper technique and by avoiding certain easily-avoidable ways of supporting the rifle, I think the shooter can manage this effectively and eliminate POI shift (or at least reduce it to the point that it is not measurable given the limits on the precision of the rifle itself). The shooter is still responsible for it, but I'm not sure it's exactly the same thing as "induced by the shooter."

The example I've personally seen where method of support has the largest impact on POI the fairly common hunting technique of shooting standing and supporting the rifle by bracing the stock, or worse, the barrel, against a tree trunk or vertical or angled tree branch. When fired, the rifle will jump sideways away from the support, sometimes surprisingly hard.

I guess you could still call this "induced by the shooter" in the sense that the shooter made a poor choice about support method that resulted in an increased tendency for POI shift.

You can pretty much eliminate the problem by using the tree for support but not actually making contact between the tree and the rifle - basically, you use the tree to support your hand and your hand to support the rifle.

I will also say that I've also seen more of a tendency for POI shifts in rifles with non-free floated barrels. I assume this is because different positions apply different forces to the forearm, and different forces on the forearm result in different forces at the contact points between the forearm and the stock. But if you're doing precision shooting, it's generally assumed you have a free-floated barrel.

Thanks for all the great info!

What are you going to shoot in the final .

Shoot it any way you want for rough sight in. Then sight it for exactly what you will shoot in the field.
200yd offhand-sight it at 200 offhand, 600 prone-sight it and keep your dope.

quote:

Originally posted by maladat:
The example I've personally seen where method of support has the largest impact on POI the fairly common hunting technique of shooting standing and supporting the rifle by bracing the stock, or worse, the barrel, against a tree trunk or vertical or angled tree branch.

Your example is so extreme (albeit valid) that it didn’t even occur to me to mention it in my discussion. It’s something I have read warned about countless times by skilled hunters and professional shooters, and something I always tell my students who may be doing nothing more demanding than using an AR type patrol rifle to engage a torso-sized target at 50 yards.