# Accuracy



## HanzCZ (Jan 29, 2008)

I need to know difrence in MOA between 10,5 barrel and 16 inch barrel.
Thanks


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## Hard H2O (Jan 29, 2008)

HanzCZ said:


> I need to know difrence in MOA between 10,5 barrel and 16 inch barrel.
> Thanks



MOA = minute of angle. It is roughly 1" @100 yards. A group of shots that fit into a 1" group center to center is said to be 1 MOA. Angles are measured in degrees. Degrees can be further divided into minutes (60 minutes per degree) and minutes are further broken down into seconds (60 seconds per minute). Think of two shots at a paper target set at 100 yards. You fire one shot and then fire a second and angle the firearm 1 minute from where the firearm was when you fired the first. The two holes will be 1 moa. On the paper they will be approximately 1" center to center.

A rifle with a 16" barrel may be more accurate than another rifle with everything identical except for a 10.5" barrel. How accurate would be an impossible qustion to answer due to the lack of other specifics in your question.


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## Diamondback 2/2 (Jan 29, 2008)

+1

H20 gave you a great break down.

As for the accuracy of a rifle barrel in MOA terms. You can talk to the manufacture and find out what MOA the barrel will hold, with whatever type of ammo used. In most cases the manufacture will know what rounds shoots the best in the barrel, and what MOA it will hold as a vice weapon.

It would be unrealistic to think you will achieve the same type of accuracy as the manufacture, simply b/c they test from a vice weapon. Meaning they are not lying down to shoot it. They lock it in a vice, and test it for grouping sizes. 

One of the big things to check with the manufacture, is what distance the barrel was tested at. 25 yards, 50 yards, 100yards. In some cases a manufacture will test the barrel at only 25 yards, if the barrel holds a ¼ inch group. They will sell it as a 1 MOA rifle…


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## HanzCZ (Jan 30, 2008)

I am talking about M4 with 16 inch barrel and 10,5 inch barrel, and i need to know accuracy let say 300m. If somebody know in MOA the difrence between this two barrels with grooving 1:7. Thanks.


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## HanzCZ (Jan 30, 2008)

Hard H2O said:


> MOA = minute of angle. It is roughly 1" @100 yards. A group of shots that fit into a 1" group center to center is said to be 1 MOA. Angles are measured in degrees. Degrees can be further divided into minutes (60 minutes per degree) and minutes are further broken down into seconds (60 seconds per minute). Think of two shots at a paper target set at 100 yards. You fire one shot and then fire a second and angle the firearm 1 minute from where the firearm was when you fired the first. The two holes will be 1 moa. On the paper they will be approximately 1" center to center.
> 
> A rifle with a 16" barrel may be more accurate than another rifle with everything identical except for a 10.5" barrel. How accurate would be an impossible qustion to answer due to the lack of other specifics in your question.


I know what MOA is, but thanks for your time.


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## WillBrink (Jan 30, 2008)

HanzCZ said:


> I am talking about M4 with 16 inch barrel and 10,5 inch barrel, and i need to know accuracy let say 300m. If somebody know in MOA the difrence between this two barrels with grooving 1:7. Thanks.



Is that something one can simply calculate? All variables would have to be identical: identical guns and ammo except for barrel length yes? If MOA is X from the gun with the 16” barrel at 300 yards, can one simply calculate the MOA of the 10” with any real accuracy? I don’t believe so, but I am not well read enough to give the definitive answer to that, so I am asking as much as pondering the answer. Never attempted to hit a target at 300 yards with a 10 “ barreled AR, but I would imagine the MOA would be approx 2-3 feet:eek:


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## Diamondback 2/2 (Jan 30, 2008)

HanzCZ said:


> I am talking about M4 with 16 inch barrel and 10,5 inch barrel, and i need to know accuracy let say 300m. If somebody know in MOA the difrence between this two barrels with grooving 1:7. Thanks.



I cannot tell you with out knowing the type of barrel, and the type of ammo.:uhh:

That is like asking what size group in MOA will a M-24 SWS hold at 300 yards. It would depend on what ammo I used, all kinds of data, and how many rounds it has through it. How well it has been maintained, and a whole lot of other stuff.

Now this is what I can give you on “rack grade” Military M-16/ M-4 (1 in 7” twist).

The accuracy requirement is 3 MOA @ 300 yards, using M855 (green tip 62 grain penetrater)

The accuracy requirement is 3 MOA @ 200 yards, using M193 (55 grain ball)

This is what the army says the weapon must be capable of, and maintain this accuracy up to 30,000 rounds.


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## Hard H2O (Jan 30, 2008)

WillBrink said:


> Is that something one can simply calculate? All variables would have to be identical: identical guns and ammo except for barrel length yes? If MOA is X from the gun with the 16” barrel at 300 yards, can one simply calculate the MOA of the 10” with any real accuracy? I don’t believe so, but I am not well read enough to give the definitive answer to that, so I am asking as much as pondering the answer. Never attempted to hit a target at 300 yards with a 10 “ barreled AR, but I would imagine the MOA would be approx 2-3 feet:eek:



Another thing is that two seemingly identical firearms, coming off the assembly line one after the other, are not going to print the same on target. They might not even favor the same ammunition.

With the M4/M16 for the most part you are talking factory barrels. You are not talking match type barrels and firearms tuned for accuracy.

So one could say that a 16" barrel should be more accurate than a 10.5" barrel. You can not say across the board that a 16" barrel will group X.X MOA and a 10.5" barrel will group X.X MOA.


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## Pete031 (Jan 30, 2008)

Hard H2O said:


> So one could say that a 16" barrel should be more accurate than a 10.5" barrel. You can not say across the board that a 16" barrel will group X.X MOA and a 10.5" barrel will group X.X MOA.



Exactly..... MOA never changes. Just what you shoot whether it is MOA, Sub MOA, or a large grouping is what changes. 
Without getting into too much ballistics, I can tell you that most rounds become ineffective with a 10.5 inch barrel. The round doesn't get the velocity it needs, and apparently starts to tumble and become ineffective after 100 meters or so.


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## WillBrink (Jan 30, 2008)

Pete031 said:


> Exactly..... MOA never changes. Just what you shoot whether it is MOA, Sub MOA, or a large grouping is what changes.
> Without getting into too much ballistics, I can tell you that most rounds become ineffective with a 10.5 inch barrel. The round doesn't get the velocity it needs, and apparently starts to tumble and become ineffective after 100 meters or so.



Ah, well that is another issue of course. There was an interesting conversation on just that topic in this thread if interested:

http://www.shadowspear.com/vb/showthread.php?t=7776&highlight=terminal+ballistics

We talked about the issues of the M4 vs standard issue m16 on the above loss of effective terminal ballistics, much less a 10" barrel


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## Pete031 (Jan 30, 2008)

WillBrink said:


> Ah, well that is another issue of course. There was an interesting conversation on just that topic in this thread if interested:
> 
> http://www.shadowspear.com/vb/showthread.php?t=7776&highlight=terminal+ballistics
> 
> We talked about the issues of the M4 vs standard issue m16 on the above loss of effective terminal ballistics, much less a 10" barrel



Thanks for the link.


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## Diamondback 2/2 (Jan 30, 2008)

Pete031 said:


> Exactly..... MOA never changes. Just what you shoot whether it is MOA, Sub MOA, or a large grouping is what changes.
> Without getting into too much ballistics, I can tell you that most rounds become ineffective with a 10.5 inch barrel. The round doesn't get the velocity it needs, and apparently starts to tumble and become ineffective after 100 meters or so.




This all depends on the type of ammo you are running, I have seen 10.5 inch barrels shoot better then some 14.5 inch barrels.  

The round tumbling is caused by weight of the bullet Vs the amount of spin from the LANs and grooves. Just like how the 1 in 12” twist on the old M-16A1, if you fire M855 (the 62 grain green tip) the bullet never stabilizes in flight, and yaws and tumbles right out of the barrel. In addition, is ineffective past 90 meters.

Now the ballistic punch or FPS (feet per second) the bullet is moving, is what is affected by barrel length. It will diminish faster the shorter the barrel is. Once you lose FPS, and the bullet is no longer supersonic, the bullet can start to yaw.


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## HanzCZ (Jan 31, 2008)

Ok, thank you. 
I red somewhere that there is big difrence between 16 and 10,5 inch barrel about 3MOA. We have  Mk262 ammo.
I am interesting about M4 (COLT)with piston and HK 416. Now we are trying to find out which barrel will be the most suitable for us. It is mean, for more tasks like CQB, .... We already have a lot of machineguns for longest distances SR25 and AWP .338 Lapua Magnum but we need something universal and compact for operator. Do you know what is the shortest barrel for M4 with M203?


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## Diamondback 2/2 (Jan 31, 2008)

HanzCZ said:


> Ok, thank you.
> I red somewhere that there is big difrence between 16 and 10,5 inch barrel about 3MOA. We have  Mk262 ammo.
> I am interesting about M4 (COLT)with piston and HK 416. Now we are trying to find out which barrel will be the most suitable for us. It is mean, for more tasks like CQB, .... We already have a lot of machineguns for longest distances SR25 and AWP .338 Lapua Magnum but we need something universal and compact for operator. Do you know what is the shortest barrel for M4 with M203?



With M203, your are going to want a 14.5" barrel. The 10.5 makes a good room broom, but the 14.5 is a better universal barrel.


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## pardus (Jan 31, 2008)

J.A.B. said:


> but the 14.5 is a better universal barrel.



Sounds good to me.


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## The91Bravo (Jan 31, 2008)

Damn the NFA!!!!


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