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  #1  
Old 10-25-2013, 3:21 PM
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Default ar gas block with flip front sight question

I am considering to replace a standard ar gas block with a flip front sight with gas block.My concern if there are any possible issues with flip front sights (accuracy, reliability, etc) and how easy to replace a gas block. I checked youtube, it looks easy there when somebody else does it.
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Old 10-28-2013, 12:04 PM
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Depends on the rifle. Are you going to free float the barrel at the same time? Or are you running hand guards? If your current gas block/sight post (I'm assuming it is a standard "A" style sight) is pinned to the barrel, you will have to pound out the pins.

I do this on a block of wood I cut to cradle the barrel and provide a place for the pin to go when pushed out. I do it on the concrete floor to remove ANY movement of the work surface.

Once you remove the pins there will be holes left in the barrel.

Are you planning to use the PRI or Vltor sights? The Vltor gas block sight is very good, I don't know about the PRI. Make sure you buy one that clamps.

If installed correctly there should be no issue with the sight. You will need to make sure you measure the diameter of the barrel at the gas block to ensure it is the correct fit for the gas block/sight

The other alternative, which I prefer is to remove the standard sight, cut it down and shape it so it will fit under a free float tube. There is a fair amount of info out there about how to "shave" the gas block. Just do a search. It is pretty easy if you have a dremel, a hack saw, and a vice.

The reason I prefer this is that I gain two things. One, I gain a free floated barrel with a tube or rail to attach stuff to Two, I retain a very strong gas block since pinning is superior to clamping OR set screws.

After you shave the gas block you can paint it or blue it. I prefer bluing with Oxpho-Blue (Brownells), it is very fast and you don't have to worry if the paint will stay on.

This method is a little more expensive because it involves buying a rail and a flip up sight, but there are advantages of a front tube/rail that are worth it to me.

Anyway, good luck
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  #3  
Old 10-28-2013, 1:09 PM
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Quote:
Originally Posted by ScottsBad View Post
Are you planning to use the PRI or Vltor sights? The Vltor gas block sight is very good, I don't know about the PRI. Make sure you buy one that clamps.

For a sight gas block? Or are you not a fan of set screw gas blocks in general?
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Old 10-28-2013, 7:10 PM
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Quote:
Originally Posted by ScottsBad View Post
Depends on the rifle. Are you going to free float the barrel at the same time? Or are you running hand guards? If your current gas block/sight post (I'm assuming it is a standard "A" style sight) is pinned to the barrel, you will have to pound out the pins.

I do this on a block of wood I cut to cradle the barrel and provide a place for the pin to go when pushed out. I do it on the concrete floor to remove ANY movement of the work surface.

Once you remove the pins there will be holes left in the barrel.

Are you planning to use the PRI or Vltor sights? The Vltor gas block sight is very good, I don't know about the PRI. Make sure you buy one that clamps.

If installed correctly there should be no issue with the sight. You will need to make sure you measure the diameter of the barrel at the gas block to ensure it is the correct fit for the gas block/sight

The other alternative, which I prefer is to remove the standard sight, cut it down and shape it so it will fit under a free float tube. There is a fair amount of info out there about how to "shave" the gas block. Just do a search. It is pretty easy if you have a dremel, a hack saw, and a vice.

The reason I prefer this is that I gain two things. One, I gain a free floated barrel with a tube or rail to attach stuff to Two, I retain a very strong gas block since pinning is superior to clamping OR set screws.

After you shave the gas block you can paint it or blue it. I prefer bluing with Oxpho-Blue (Brownells), it is very fast and you don't have to worry if the paint will stay on.

This method is a little more expensive because it involves buying a rail and a flip up sight, but there are advantages of a front tube/rail that are worth it to me.

Anyway, good luck
I have a Magpul hand guard with an A-style sight/block that came with the upper. I got a new Burris mount and waiting for a new scope to come. I got two issues with a new design - first the rear sight does not fit anymore with the Burris mount and second the front sight is on the scope way when the scope sits low. Initially I though of replacing it with a gas block tower with folding sight either YHM (found a good deal on it)or Midwest industries. Now I am leaning toward the second option you mentioned. I liked the idea of cutting the front sight and leaving the original gas block untouched. A free floated barrel with a tube with rails (probably MI) will solve my problem with positioning backup iron sights plus I read on the web that free float barrels are considered more accurate. As you pointed it is a bit more expensive but it seems to suite me better. I used to do some metal work once. Now I am wondering how so simple solution never crossed my mind. Thanks for the advice.
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Old 11-12-2013, 12:14 AM
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Quote:
Originally Posted by TMcC View Post
For a sight gas block? Or are you not a fan of set screw gas blocks in general?
For the sight gas block.
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Old 11-12-2013, 12:16 AM
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Quote:
Originally Posted by APV View Post
I have a Magpul hand guard with an A-style sight/block that came with the upper. I got a new Burris mount and waiting for a new scope to come. I got two issues with a new design - first the rear sight does not fit anymore with the Burris mount and second the front sight is on the scope way when the scope sits low. Initially I though of replacing it with a gas block tower with folding sight either YHM (found a good deal on it)or Midwest industries. Now I am leaning toward the second option you mentioned. I liked the idea of cutting the front sight and leaving the original gas block untouched. A free floated barrel with a tube with rails (probably MI) will solve my problem with positioning backup iron sights plus I read on the web that free float barrels are considered more accurate. As you pointed it is a bit more expensive but it seems to suite me better. I used to do some metal work once. Now I am wondering how so simple solution never crossed my mind. Thanks for the advice.
You still need to remove the A sight before cutting it down. Not that hard.
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Old 11-13-2013, 2:48 PM
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Quote:
Originally Posted by TMcC View Post
For a sight gas block? Or are you not a fan of set screw gas blocks in general?
I had nothing but issues with set screw gas blocks. I finally installed a Vltor clamp block and it is bulletproof. On a low profile pinch clamp style block, you have 360 degs of clamping force over the length of the block. With set screws, you have a few millimeters of surface area.

Pinned blocks are 100% reliable, but try to take one off even once the pins are out and you'll want a clamp style.
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Old 11-13-2013, 6:22 PM
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Originally Posted by VendetAR View Post
I had nothing but issues with set screw gas blocks. I finally installed a Vltor clamp block and it is bulletproof. On a low profile pinch clamp style block, you have 360 degs of clamping force over the length of the block. With set screws, you have a few millimeters of surface area.

Pinned blocks are 100% reliable, but try to take one off even once the pins are out and you'll want a clamp style.
Makes sense. Thanks for the input.
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  #9  
Old 11-13-2013, 8:06 PM
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There are a few advantages to running a barel mounted front sight versus a rail mounted front sight. The barrel mounted front sight will not be affected by mis-alignment of the free float rail, either from installation issues or pressure from a sling. On forends of the same length, you'll get a slightly longer sight radius by mounting on the barrel, ahead of the free float rail. Mounting on the barrel also gives more rail surface on the forend for running night vision optics, should you ever decide to try out pig hunting at night.

I try to run barrel mounted front sights whenever possible, but once you go shorter mid or carbine length gas systems the advantages of mounting to the barrel are outweighed by the shorter sight radius and forend length needed for a gas block sight. My 16" and 14.5" barrels all run rail mounted front sights on rifle length forends. 18" and 20" guns all get barrel mounted gas block sights.

I've had good experiences running the gas block sighs from PRI and YHM. PRI makes a pretty Gucci folding sight/gas block, but it's pricey. The various models of YHM front gas block sights are really good as well, for about half the price of the PRI.
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  #10  
Old 11-14-2013, 8:46 PM
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I have this front and rear sight set on two of my AR's



With this flip up for the rear, I usually always leave it on the smallest diopter because these 50 yr old eye's need all the help.


They work perfectly and are very accurate, the only mod was to change out the sight post with .034 or .052 round dot post for iron sight shot's to 100 yards.



http://www.knsprecisioninc.com/gun-p...ssortment.html
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