I have a S&W M&P15 TS and I'm trying to set it up to be as close to an M4 performance wise as I can. specifically I'm a little confused about the sight radius. I want it to be the same as a standard M4 and I'm not sure where to mount the front sight. It is my understanding that the sight radius is 14.5". measured out on the TRX it came with it is forward of the gas block. should I move the front sight back directly over the gas block or are my dimensions correct as they are?
AR sight radius
- Thread starter UM3Gun
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You want your sight radius to be as long as possible no matter what type of rifle you are using. Mount your rear sight as far to the rear as you can, and mount your front sight as far forward as it can go without hanging over the front of your rail system. Just like the picture..
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The M4 sight radius isn't optimum, it's an institutional compromise. These days with a red dot as standard issue, it's not even used, BUIS often aren't mounted at all.
The M4 is also a NFA 14.5" barrel, also a compromise. Why is a completely off topic and controversial thread on it's own. One area of concern to take from that is what the .Gov sees as a need for a broad based application for various user groups isn't what is best for YOU. And what some perceive as their trend in developing an urban/CQB application stemmed from the original goal to provide a PDW for NON combat users and special operations forces.
However, once the air divers and officers got them, they became "cool." Visually they couldn't be differentiated as the two completely different users they were, and the Army used the same base gun for both - it was the gear clamped on them (or not,) that told the story.
Point being, we saw the M4 go from being issued to truck drivers (where it is helpful,) to the M4 being issued to Infantry on foot patrol in the Afghan highlands, where it's been called into question (let's leave it at that.) And the answer was to reintroduce the 20" barreled accurized Squad Designated Marksman to compensate, among others.
For urban and vehicular use, a 14.5" barrel can do, but as a lot of guys incounty will tell you, a 10" submachine gun purchased off the market bazaar is better. And for being out in the field away from the city, 20" or longer rifles have been the standard for centuries. For good reasons.
The M4 is just a current fad, made larger by all the hype over CNC accessories, which is a cheap way to produce high precision small parts economically when volume is small - not because it's intrinsically better. Just the cheapest way for production of those numbers. You see the same thing going on in hot rod parts, too - and it's just as filled with hype and marketing.
Point being, choose the configuration for YOUR rifle to do what you need ballistically, and don't slavishly copy any one unless that's what your willing to accept - warts, compromises, and all. Then it's an accurate homage, but that doesn't mean it's the real thing.
Those come with free ammo, and are quite affordable that way.
The M4 is also a NFA 14.5" barrel, also a compromise. Why is a completely off topic and controversial thread on it's own. One area of concern to take from that is what the .Gov sees as a need for a broad based application for various user groups isn't what is best for YOU. And what some perceive as their trend in developing an urban/CQB application stemmed from the original goal to provide a PDW for NON combat users and special operations forces.
However, once the air divers and officers got them, they became "cool." Visually they couldn't be differentiated as the two completely different users they were, and the Army used the same base gun for both - it was the gear clamped on them (or not,) that told the story.
Point being, we saw the M4 go from being issued to truck drivers (where it is helpful,) to the M4 being issued to Infantry on foot patrol in the Afghan highlands, where it's been called into question (let's leave it at that.) And the answer was to reintroduce the 20" barreled accurized Squad Designated Marksman to compensate, among others.
For urban and vehicular use, a 14.5" barrel can do, but as a lot of guys incounty will tell you, a 10" submachine gun purchased off the market bazaar is better. And for being out in the field away from the city, 20" or longer rifles have been the standard for centuries. For good reasons.
The M4 is just a current fad, made larger by all the hype over CNC accessories, which is a cheap way to produce high precision small parts economically when volume is small - not because it's intrinsically better. Just the cheapest way for production of those numbers. You see the same thing going on in hot rod parts, too - and it's just as filled with hype and marketing.
Point being, choose the configuration for YOUR rifle to do what you need ballistically, and don't slavishly copy any one unless that's what your willing to accept - warts, compromises, and all. Then it's an accurate homage, but that doesn't mean it's the real thing.
Those come with free ammo, and are quite affordable that way.
Zach S
Member
I agree. They look goofy, but dissipators are my favorite arrangement.
JustinJ
Member
Assuming it has a carbine length gas system just mount the front sight over the gas block and it will match that of the M4. But as others have said the longer the better.
Deus Machina
Member
In that case, find the spot an M4 would have the sights, then move the front one back a bit.
This would be akin to an olympic runner training in his mechanic's boots, then using the sponsored featherweight shoes for the actual race.
Really, though, red dots are issued and you'll probably never end up using the irons.
This would be akin to an olympic runner training in his mechanic's boots, then using the sponsored featherweight shoes for the actual race.
Really, though, red dots are issued and you'll probably never end up using the irons.
henschman
Member
An M4's sight radius, with the factory carry handle, is 14.5", just like you said.
The reason why that might place the front sight farther forward than the gas block on your rifle is that you are not using a carry handle sight. Most flip-up rear sights put the rear sight aperture a little farther forward than a factory carry handle sight.
In the service, you will probably not be using a carry handle sight either. Most M4s are issued with a Matech flip-up rear sight (though some guys buy a different one on their own). So if you want to simulate that type of setup, the front sight should be placed over the front end of the gas block, which is just where it would be if you had a GI front sight on your rifle.
The reason why that might place the front sight farther forward than the gas block on your rifle is that you are not using a carry handle sight. Most flip-up rear sights put the rear sight aperture a little farther forward than a factory carry handle sight.
In the service, you will probably not be using a carry handle sight either. Most M4s are issued with a Matech flip-up rear sight (though some guys buy a different one on their own). So if you want to simulate that type of setup, the front sight should be placed over the front end of the gas block, which is just where it would be if you had a GI front sight on your rifle.
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