A question about sight radius > Build It Yourself

Posted: 7/1/2006 6:53:03 AM EDT

I just started work on my first build and remember reading somewher that the sight radius on a 16" barrel is different than on a 20" barrel. My question is just how noticeable is the difference? All I've ever shot is the 20" and want to be able to pick up my new toy and go shooting without having to get used to a radically different sight picture.

I figure that if its too noticeable I can always just got for a dissipator type setup.

Thanks for the assist.hug.gif

Posted: 7/1/2006 7:01:23 AM EDT

[#1]

The only difference you should even worry about is when zeroing it. Due to the shorter sight radius of the 16" rifle, you won't need to turn the front post or rear windage as much as you would on the longer gun. You probably won't tell a difference in how your sight picture looks.

Posted: 7/1/2006 9:59:43 AM EDT

[#2]

It's nothing to worry about. If you are familiar with the 20", you will be fine with a 16". You could go with a 16" with the mid-length gas system. It would have a longer sight radius then a M4/CAR setup.

Posted: 7/7/2006 1:13:17 PM EDT

[#3]

The actual (measured) sight radius of my ARs is:

M4 16" 374 mm
Hbar 20" 510 mm
both with A2 removable handle.

It's about 27% difference that IMO effects aiming quality.

About click adjustment at 100 m, these are my findings:

M4 @100 m: front sight elevation 4.62 cm/click, rear sight windage 1.84 cm/click, rear sight elevation 1.87 cm/click
HABAR @100m: front sight elevation 3.4 cm/click, rear sight windage 1.35 cm/click, rear sight elevation 1.37 cm/click

Hope this helps.

Posted: 7/10/2006 5:07:39 AM EDT

[#4]

Thanks for the gouge. I've think that the dissipator is the way for me to go.

Posted: 7/10/2006 12:29:02 PM EDT

[#5]

Quoted:
I just started work on my first build and remember reading somewher that the sight radius on a 16" barrel is different than on a 20" barrel. My question is just how noticeable is the difference? All I've ever shot is the 20" and want to be able to pick up my new toy and go shooting without having to get used to a radically different sight picture.

I figure that if its too noticeable I can always just got for a dissipator type setup.

Thanks for the assist.

Your eyesight can be a factor. I am 42, with less than perfect eyesight. I find it difficult to focus on the front sight post of my carbine, but have no problem at all focusing on the front sight post on my rifle. My $0.02, FWIW.

If this is an issue for you (and you can live without the ability to use a bayonet) a Dissipator-type carbine might be the ticket. They maintain the full-length sight radius.

Posted: 7/20/2006 8:31:31 AM EDT

[#6]

Hello,

I was about to start a new thread on a similar topic, but I thought I would reply here and see what I get. I just saw the dissipator model from BM, and realized that I have always thought the front sight post seemed a little too fat on my regular 16" BM, especially at 50 to 100 yard shooting. My question is this: assuming you don't already have a dissipator model, what can you do to your normal 16" to fix this?

Is there a way to move the entire front sight assembly farther up the barrel without serious tools? (Apologies if this is a stupid question, I'm not much of a tinkerer)

Would just getting a thinner front sight post help? If so, does anyone sell a front sight post that is just thin enough that it would look the same size as a standard front sight post on a 20" rifle?

Essayons: I'm not quite 42 yet, but I'm blessed with the eyesight of 42 yrs +. I also find it difficult to focus on the front sight post.

Posted: 7/20/2006 10:30:57 AM EDT

[#7]

I have a KNS "thinner" front sight I forget the exact number.

Posted: 7/21/2006 7:19:15 PM EDT

[#8]

Quoted:

Quoted:
I just started work on my first build and remember reading somewher that the sight radius on a 16" barrel is different than on a 20" barrel. My question is just how noticeable is the difference? All I've ever shot is the 20" and want to be able to pick up my new toy and go shooting without having to get used to a radically different sight picture.

I figure that if its too noticeable I can always just got for a dissipator type setup.

Thanks for the assist.

Your eyesight can be a factor. I am 42, with less than perfect eyesight. I find it difficult to focus on the front sight post of my carbine, but have no problem at all focusing on the front sight post on my rifle. My $0.02, FWIW.

If this is an issue for you (and you can live without the ability to use a bayonet) a Dissipator-type carbine might be the ticket. They maintain the full-length sight radius.

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