AR 15 front sight (gas block) replacement and front sight?

[Rule3]

I have a older AR 15 with a regular A2 front sight. I put a nicer quad rail forend on it. I want to put a reflex type sight on it. Of course the A2 sight stands up in the way. I have a Mbus rear flip up sight now and it is sighted in with the existing A2 sight,

Anyway, I want to replace the front gas block to a low profile. Do I need to get one with short rail on top (to mount a flip front sight) or can I just put the flip up front sight on the end of the forend quad rail. It goes right up to the A2 sight.

I was not sure if the distance between the rear sight and front sight was that tactical?? (it is carbine length if that matters?)

Hope this makes sense

Thanks

 

[KansasPaul]

You may need to conduct a little research before you purchase the new gas block and front sight. Assuming that the rail is the same height as the top of your receiver and that the front and rear flip sights are the same height you should be okay (meaning that you wouldn't need a gas block with rail).

Paul

 

[Zerodefect]

My first 2 recommendations aren't exactly what you're looking for.

1st, before modifying the rifle, get a good Larue mount for your optic that offers lower 1/3rd cowitness. I think you'll find that the front sight will not be in the way at all with that setup.

Then, if you still want to get rid of the front sight, I'd put a Mas Defense Lowpro steel gas block on the rifle with a longer rail that covers the gas block instead of a flip front sight gas block. Then just use a rail mounted BUIS.

But if you do get a railed gas block for front flip sight mounting, note that the flip front sight will need to be taller than a regular rail mounted BUIS.

 

[Rule3]

The quad rail I put on is level with the receiver so if both the front and rear sight are on those I would be good.

My question. I guess is would the front sight need to be further out to were the A2 sight is now, say about 1" further.? If not then I can just get a low gas block with no rail on it.

The distance from the rear sight to the where the front sight would be (on the quad rail) would be around 13" The A2 sight is another 1" or so in front of that.

Zerodefect, Are you saying just get a type of riser that would have the optic sight over the existing A2 sight?

If I put the optic on now the dot or circle hits exactly on the top of the A2 front sight.

 

[Zerodefect]

For example a Larue LT129 will hold an olde Aimpoint nice and high so that you BUIS will cowitness, but only in the bottom of the optics window. With the rear sight folded down, your front sight won't be in the way at all. It'll be visible, but not in the way. The dot'll be about 3/8" over the front sight.





What optic are you planning to run?

 

[Rule3]

Thanks for the picture, that helps.

So with your elevated mount it clears the front sight? If so then I guess the easy way for me is to just put a riser on (I may have one around here) and forget the hassle and expense of a low gas block.

The optic is a cheap Sightmark. it has quick release mount. but I got it as it is all green reticles (i can not see red very well) It is actually very bright. Not sure how well it will hold up.

My only interest in perhaps changing the gas block is so I can remove the optic and use fixed sights or as "back up" I was keeping this rifle as a beater or "truck" gun. I am not too concerned with the flip up sights lining up with the optic or "cowitness" If the battery dies or it breaks I can just pull it off and still shoot wit the flip ups.

I have a nicer rifle, with a good scope on it for longer range shooting

 

[USAF_Vet]

I have a older AR 15 with a regular A2 front sight. I put a nicer quad rail forend on it. I want to put a reflex type sight on it. Of course the A2 sight stands up in the way. I have a Mbus rear flip up sight now and it is sighted in with the existing A2 sight,

Anyway, I want to replace the front gas block to a low profile. Do I need to get one with short rail on top (to mount a flip front sight) or can I just put the flip up front sight on the end of the forend quad rail. It goes right up to the A2 sight.

I was not sure if the distance between the rear sight and front sight was that tactical?? (it is carbine length if that matters?)

Hope this makes sense

Thanks

Read THIS thread. It'll answer a lot of your questions.
Also, if you're going to use a railed gas block, read THIS thread as well.

Personally, my carbine runs a 16" barrel, mid length gas system, 15" quad rail with the forward sight mounted to the end of the quad rail. The increased sight radius does seem to help accuracy, and you don't need a riser (or taller front sight) to mount on the gas block.

 

[Zerodefect]

 

[Rule3]

Maybe pictures will help. The little piece in front of the sight is the bracket that holds my brass catcher.

So, should I just use a riser, to mover the optic up so it clears the front A2??

 

[rjrivero]

If you show a pic of your sight with the reticle in the center, you'll probably have a low 1/3 co-witness with your front sight post. This is arguably the desired setup and if you don't know why: Putting your front sight post in the center of your optic (using your optic as a large peep sight) would get you minute of bad guy at room clearing distance, if your optic ever **** the bed at the wrong time.

 

[Malamute]

If you have concluded you want to remove the existing fixed front sight, the simplest, cheapest way is to just cut the sight off the gas block. It will likely also give you a stronger mount than some that only use set screws. It may sound hillbilly, but its fairly common. Cut off with hacksaw or whatever you have, file the edges off rounded, cold blue or paint.

 

[Rule3]

The picture I took is not the best. Holding the rifle level the A2 is pretty much in the center of the optic. I also did not show a pic with the rear sight up. It may very well be lined up OK. I need to go to the range and test it.

I have seen pics of the front sight hacked off. I am not going to "Bubba" it I did consider it though With removing the front sight I loose my sling swivel also and to replace a low one with a swivel is expensive

If need be I will just leave it as is, and put the optic on another rifle, I could even put the carry handle back on. No sense spending more money on this rifle than the optic cost.

 

[Malamute]

I believe the main difference between a bubba sight cut-off job and a good one is the part after the saw work is done. A quality clean up and finish will look like quality work.

 

[BigBore45]

Just get a 1" riser for the reflex sight

 

[Rule3]

Just get a 1" riser for the reflex sight

That would be to easy


Yes, I could cut the sight and make it look nice but that is a last resort.