Mil Dot and MOA

[Guest ORgunner]

I came across these videos on youtube earlier. I think he does a great job of simplifying the meaning of each and makes it a lot easier to understand. Just thought someone could use these.

Mils

MOA

[Guest BillOfRightsFan]

That's Ryan Cleckner and he is the bomb when it comes to shooting instruction. His instructions are always clear, sensible and he get to the point right away. Also, he walks the walk and is a total pro in long range shooting.

[JohnC]

Thank you! I've been wanting to learn all of this! Know of any good books as well on the subject?

[Guest ORgunner]

No i do not know of any books. I agree he does a great job of making it simple though.

[JohnC]

I just got a Nikon M-223 3-12x42 BDC 600 and I think these videos will help!

Also, Nikon has an online Ballistic calculator at www.nikonhunting.com/spoton for these scopes. You just register your info and then your in!

[JohnC]

Couple crappy iPhone pics.

Sent from my iPhone using Tapatalk

[Ropin4gold]

As far as a book about sniping, or long range shooting; you should look at the Ultimate Sniper by Plaster.

[Dolomite_supafly]

What I hatge about ballistically matched reticles and turrets is they rarely match real world performance. The velocity is not going to be even remotely close between a 16" gun and a 24" gun. In most cases the velocity will be different by about 40 fps per inch of barrel length with most 223 loads. The heavier bullets exhibit less while lightweight bullets exhibit more.

The turrets say 3,240 fps but what happens if the actual veclocity is say 3,100 fps? At 500 yards the bullet drops an additional 7" thats what. And that is when the conditions are the same. Now the difference in drop between 49 and 89 degrees is another 3.5". A bullet drops less in hotter weather than in cooler weather because of air density.

There are just too many variables that can affect bullet performance for a ballistically matched anything to be correct all the time or even most of the time.

The best way to make sure you can place accurate shots on target is this.

First and foremost chronograph the ammunition to get the real numbers, even if the ammo is factory ammo. I have yet to find a rifle ammunition that matches its advertised numbers in any of my platforms. Providing the ammunition stays relatively close to the temperature as when you chronograph it will be the constant. Also, those numbers will not change very much based on ambient temperature or humidity in the 10' to the chronograph. The normal variance will be more.

Now that you have the REAL velocity use it to make a ballistic chart. It should be based on where you are going to be shooting or hunting and should be for current conditions, not 6 months prior. You can also use one of the ballistic programs available to make on the fly corrections based on current weather conditions.

Dolomite

[mikegideon]

This one is on my short list. Not sure which reticle yet...

http://www.vortexoptics.com/product/vortex-viper-pst-6-24x50-ffp-riflescope-with-ebr-1-moa-reticle/reticle

[JohnC]

What I hatge about ballistically matched reticles and turrets is they rarely match real world performance. The velocity is not going to be even remotely close between a 16" gun and a 24" gun. In most cases the velocity will be different by about 40 fps per inch of barrel length with most 223 loads. The heavier bullets exhibit less while lightweight bullets exhibit more.

The turrets say 3,240 fps but what happens if the actual veclocity is say 3,100 fps? At 500 yards the bullet drops an additional 7" thats what. And that is when the conditions are the same. Now the difference in drop between 49 and 89 degrees is another 3.5". A bullet drops less in hotter weather than in cooler weather because of air density.

There are just too many variables that can affect bullet performance for a ballistically matched anything to be correct all the time or even most of the time.

The best way to make sure you can place accurate shots on target is this.

First and foremost chronograph the ammunition to get the real numbers, even if the ammo is factory ammo. I have yet to find a rifle ammunition that matches its advertised numbers in any of my platforms. Providing the ammunition stays relatively close to the temperature as when you chronograph it will be the constant. Also, those numbers will not change very much based on ambient temperature or humidity in the 10' to the chronograph. The normal variance will be more.

Now that you have the REAL velocity use it to make a ballistic chart. It should be based on where you are going to be shooting or hunting and should be for current conditions, not 6 months prior. You can also use one of the ballistic programs available to make on the fly corrections based on current weather conditions.

Dolomite

I get what your saying and I don't expect the BDC to be surgical precision.

But if you use their website calculator, you can key in everything down to hand loaded ammo or factory, weather, etc., and print it out. Then, those BDC marks, instead of 100-600 yards becomes odd numbers like 186 yards, etc, but should get you hitting the target.

Correct me if I'm wrong though.

Calculated without weather conditions for 5.56 NATO FMJ 62gr, etc...

Adding weather:

BDC with weather compensation:

[mikegideon]

That's quite a bit of work just to avoid a Mil Dot . I have one of the Nikon BDC scopes. It has it's pros, but I prefer Mil dot.

[Johnny Rotten]

you will not get surgical precision from a 16" carbine rifle unless were talking about 100yrds

[mikegideon]

you will not get surgical precision from a 16" carbine rifle unless were talking about 100yrds

Not true. 16" barrels can be very accurate. There's a hit in velocity, so you're bullets will run out of smoke before they will from a 24" barrel. That happenns WAY past 100 yards.

[Dolomite_supafly]

And all things considered a shorter barrel will be more accurate than a longer barrel.

The reason is with a shorter vs thickness barrel has more stabile barrel harmonics. Longer barrels have more whip and that whip is what causes inaccuracies until a load is found it likes. You want a round that exits at exactly the same time of the barrel whip.

The only time a longer barrel can be more accurate is if iron sights are being used. The longer sight radius contributes to the accuracy not the barrel itself.

And caliber has very little to do with accuracy, the platform does have more of an impact on overall accuracy.

Dolomite

[Guest BungieCord]

What I hatge about ballistically matched reticles and turrets is they rarely match real world performance....

My gripe is that they anchor you to one MV at one ambient temp at one elevation. Change any one of the three and the shooter has to split hairs to adjust. To my hillbilly brain, it's easier just to use Mils or MoA and print custom range card(s) for the conditions I anticipate encountering. That way I don't have to do so much cogitating in the field.

[mikegideon]

My gripe is that they anchor you to one MV at one ambient temp at one elevation. Change any one of the three and the shooter has to split hairs to adjust. To my hillbilly brain, it's easier just to use Mils or MoA and print custom range card(s) for the conditions I anticipate encountering. That way I don't have to do so much cogitating in the field.

Yep. I thought they were cool when I first saw them. Now, just give me a Mil dot for unknown ranges, and a plain old crosshair for known ranges.

[Johnny Rotten]

And all things considered a shorter barrel will be more accurate than a longer barrel.

The reason is with a shorter vs thickness barrel has more stabile barrel harmonics. Longer barrels have more whip and that whip is what causes inaccuracies until a load is found it likes. You want a round that exits at exactly the same time of the barrel whip.

The only time a longer barrel can be more accurate is if iron sights are being used. The longer sight radius contributes to the accuracy not the barrel itself.

And caliber has very little to do with accuracy, the platform does have more of an impact on overall accuracy.

Dolomite

I hear what your saying but:

I recently sold a colt HBAR AR15 with a 20" A2 upper, that thing was way more accurate then any of my 10.5",11.5", 14.5" and 16" uppers that I currently use.....using the same ammo...

I was in the market for a REPR last yr but settled for something else, please look at page 5 for how LWRC rates their rifle for ranges, shorter barrels = shorter distances, longer barrels = longer distances.

It's a different caliber but I'm thinking it's the same theory...

http://www.lwrci.com/support/forms/REPR_Manual.pdf

JR

[mikegideon]

Shorter barrel=slower bullet=more arc in the trajectory. Got nothing to do with accuracy until the bullet slows way down. It does require more skill in compensating for bullet drop.

[Guest BungieCord]

... please look at page 5 for how LWRC rates their rifle for ranges, shorter barrels = shorter distances, longer barrels = longer distances....

There are any number of reasons besides length why one barrel might be more accurate than another. But the simple fact is that the tendency is for shorter barrels to be more accurate.

Nowhere does that manual say or imply that accuracy is dependent on barrel length. All it says is that a rifle with barrel length "X" is "suitable" for engaging targets to range "Y." You're assuming the rest.

I don't know what their definition of a "suitable" range is but, considering the context, one would presume it is something akin to max effective range, and MER at the very least considers accuracy and lethality.

Their use of "suitable" range instead of the customary military term probably is a clue that they're using their own custom standards that exceed the military's definition of MER. And with the ranges they've selected, I'd bet speed of sound was a key consideration. They claim their 20" REPR is "suitable" for engaging point targets to 1000 yards, and 20" is not a lot of barrel for shooting the .308 to 1000 yards if you're expecting to still be supersonic. Same with 18" and 800 yards, and 16" and 600 yards.

Still another possibility is the ability to use 'standard' combat optics, like the ACOG and the Aimpoint M3, without resorting to canted scope rails. The manual mentions that their rifles should be used with "bullets heavier than 168 grains for peak accuracy." Heavier bullets will produce a lower MV, and it could be the more pronounced arc of that slow a bullet exceeds the limits of vertical adjustment one or more of the 'standard' combat optics at that range. But that's just speculation.

But it definitely ain't because shorter barrels are less accurate.

[Johnny Rotten]

OK wow, I'm in learning mode now (not a smart AZZ comment)..

then why do they make barrels longer then 16" if it doesn't matter (other then fps is greater out of a longer barrel)? and why do the make bull barrels??

BTW: I already learned something off the MOA video above

[Dolomite_supafly]

OK wow, I'm in learning mode now (not a smart AZZ comment)..

then why do they make barrels longer then 16" if it doesn't matter (other then fps is greater out of a longer barrel)? and why do the make bull barrels??

BTW: I already learned something off the MOA video above

Accuracy and range are two different things.

A fully prepped .22 lr will shoot circles around any AR inside of 100 yards. But the range of the AR is much father than a 22 lr.

Barrel stiffness is a result of length vs width. A long thin barrel will be less stiff than a barrel of the same length but twist as thick. Likewise a barrel that is 1/2 as long but as thin as the thin one will be stiffer than the original thin barrel.

As a gun fires the barrel whips just like a bullwhip just on a microscopic level. And this whip can be affected by the thickness of the barrel and the length. This is why it is much harder to get a sporter barrel to shoot a wider range of ammunition accurately.

The reason why bull barrels are made is to make the barrel stiffer. The stiffer the barrel the less wildly the whip of the barrel harmonics will be. And if there are less harmonics that barrel exhibits it while tend to shoot better with a wider range of ammunition. It will also be easier to tune the loads to squeeze the most accuracy out of it. And during tuning your loads you want the bullets to exit at exactly the same point in the whip.

Dolomite

[mikegideon]

A thick barrel is also changes point of impact less as it heats up.

[Dolomite_supafly]

A thick barrel is also changes point of impact less as it heats up.

Yes but the shift has more to do with the concentricity of the bore to the outside of the barrel.

A thick barrel with an off center bore (yes it happens) will shift more than a sporter barrel with the bore concentric to the outside. But the shift can be more pronounced with a thinner barrel than a thicker barrel.

Dolomite

[mikegideon]

Yes but the shift has more to do with the concentricity of the bore to the outside of the barrel.

A thick barrel with an off center bore (yes it happens) will shift more than a sporter barrel with the bore concentric to the outside. But the shift can be more pronounced with a thinner barrel than a thicker barrel.

Dolomite

My worst may be my Browning X bolt in .243. Haven't played with it enough to document it, but it moves as the barrel warms up.

[Dolomite_supafly]

I had a Savage that shot honest to goodness groups of .5". And it did it for exactly 3 rounds. The 4th round was 1/2" to the left. The 5th round was 1" to the left. I never shot more than that at a time. In retrospect I would have really liked to see how far it would have drifted. Maybe I was the holder of a Cornershot before they had even been invented.

I tried everything I could to resolve the issue but in the end I just put a tensioning sleeve over the barrel. That fixed the heat related drift and did it cheaper than rebarreling. It also did it without adding a substantial amount of weight.

Dolomite