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Posted: 10/8/2012 7:43:19 AM EDT
I ordered an Aimpoint for my LE6920. I wish to replace the stock front sight with a flip up BUIS. I don't want to skimp on quality. I found a Troy Industries M4 gas block flip up sight I like. I want to go this direction so I can keep my MAGPUL MOE carbine length hand guard which I like very much. I'm not clear if it includes a new gas block or the original block is modified.  I have read that aftermarket gas blocks can be problematic as they may rotate and block the gas port. I don't want to give up any reliability. Has anyone used this sight? Do I have anything to worry about? What steps can be taken to make sure it's a first rate and trouble free install?
Link Posted: 10/8/2012 8:16:01 AM EDT
First off, it's a great, high quality sight.

Unfortunately, it's pretty complex if you want to mount one of those.  They DO NOT come with a gas block.  Their main function is to be situated on a freefloating rail, which would utilize a low profile gas block (either a modified front sight base like on your 6920 with the triangular sight chopped off, or a purpose built low profile gas block).  Since you say that you want to keep your MOE handguards, this would mean that you would have to get a new gas block with a rail on top.  However, it cannot be any gas block with a rail; it has to be one of the taller variety (some are too short and are designed for a taller front sight than the Troy).  Here is one that would work: link

As far as installation goes, the hardest part will be getting your existing front sight base (and no, this cannot be used to mount a Troy sight) off of the rifle.  It took me three hours of cursing, sweating, and hammer swinging to get mine off.  Not fun.  Your replacement gas block will be of either the cross bolt tension style, or a set screw style.  If you dimple the barrel for the set screw, I think that is likely your best bet.  They are strong enough when properly installed.

Again, this is a big project if you choose to do it.  I honestly think there are better options.  If you do it anyway though, remember that Magpul makes a front sight that would match your rear sight (Troy of course makes a rear sight as well, if you ditched the rear Magpul sight).
Link Posted: 10/8/2012 8:21:19 AM EDT
Quoted:
First off, it's a great, high quality sight.

Unfortunately, it's pretty complex if you want to mount one of those.  They DO NOT come with a gas block.  Their main function is to be situated on a freefloating rail, which would utilize a low profile gas block (either a modified front sight base like on your 6920 with the triangular sight chopped off, or a purpose built low profile gas block).  Since you say that you want to keep your MOE handguards, this would mean that you would have to get a new gas block with a rail on top.  However, it cannot be any gas block with a rail; it has to be one of the taller variety (some are too short and are designed for a taller front sight than the Troy).  Here is one that would work: link

As far as installation goes, the hardest part will be getting your existing front sight base (and no, this cannot be used to mount a Troy sight) off of the rifle.  It took me three hours of cursing, sweating, and hammer swinging to get mine off.  Not fun.  Your replacement gas block will be of either the cross bolt tension style, or a set screw style.  If you dimple the barrel for the set screw, I think that is likely your best bet.  They are strong enough when properly installed.

Again, this is a big project if you choose to do it.  I honestly think there are better options.  If you do it anyway though, remember that Magpul makes a front sight that would match your rear sight (Troy of course makes a rear sight as well, if you ditched the rear Magpul sight).


Two problems with your response. Troy makes a front sight specifically for mounting onto the shorter railed gas blocks. From reading the OP, it looks like this is the one he is looking at. And, Magpul says their sight can melt on gas blocks, therefore it is is not recommended to mount them there.
Link Posted: 10/8/2012 8:30:47 AM EDT
Quoted:
I ordered an Aimpoint for my LE6920. I wish to replace the stock front sight with a flip up BUIS. I don't want to skimp on quality. I found a Troy Industries M4 gas block flip up sight I like. I want to go this direction so I can keep my MAGPUL MOE carbine length hand guard which I like very much. I'm not clear if it includes a new gas block or the original block is modified.  I have read that aftermarket gas blocks can be problematic as they may rotate and block the gas port. I don't want to give up any reliability. Has anyone used this sight? Do I have anything to worry about? What steps can be taken to make sure it's a first rate and trouble free install?

Look before you leap.

Try the Aimpoint before changing out your irons.

Absolute or 1/3 co-witness ?
Link Posted: 10/8/2012 8:57:00 AM EDT
Quoted:
Quoted:
I ordered an Aimpoint for my LE6920. I wish to replace the stock front sight with a flip up BUIS. I don't want to skimp on quality. I found a Troy Industries M4 gas block flip up sight I like. I want to go this direction so I can keep my MAGPUL MOE carbine length hand guard which I like very much. I'm not clear if it includes a new gas block or the original block is modified.  I have read that aftermarket gas blocks can be problematic as they may rotate and block the gas port. I don't want to give up any reliability. Has anyone used this sight? Do I have anything to worry about? What steps can be taken to make sure it's a first rate and trouble free install?

Look before you leap.

Try the Aimpoint before changing out your irons.

Absolute or 1/3 co-witness ?


THIS!!! I was looking for the same sight to mount on my gas block when I mounted my red dot sight. I had a fixed sight on it and after mounting the red dot, realized that it does not hurt my ability to sight in a target. I don't even notice it most of the time. Give it a shot first.
Link Posted: 10/8/2012 9:58:09 AM EDT
I'm willing to try a cowitness, even though it just seems all wrong to me. The Aimpoint I ordered is a PRO. I'm going to try the provided mount even though a lot of guys don't like it.  What sight picture should I expect with this setup on my LE6920?
Link Posted: 10/8/2012 10:36:41 AM EDT
Quoted:
I'm willing to try a cowitness, even though it just seems all wrong to me. The Aimpoint I ordered is a PRO. I'm going to try the provided mount even though a lot of guys don't like it.  What sight picture should I expect with this setup on my LE6920?

The brain says "Hmmm...that FSB will be in the way of my optic.I must remove it."
I wouldn't volunteer to remove the FSB until I tested the optic with the FSB in place.

Aimpoint Pro w/irons

Link Posted: 10/8/2012 12:18:09 PM EDT
Quoted:
I'm willing to try a cowitness, even though it just seems all wrong to me. The Aimpoint I ordered is a PRO. I'm going to try the provided mount even though a lot of guys don't like it.  What sight picture should I expect with this setup on my LE6920?


You should have a 1/3 co-witness type sight picture.  I have the ML2, which is essentially the PRO with a 4moa dot, and I have had no problems. I never notice the FSB in my scope when I am shooting with my dot. When you look through the scope for the first time you perceive that the front sight will be distracting but when you actually shoot it you will be concentrating on the dot and the target and everything else is ignored. That's a great sight by the way, probably the best deal going right now as far as price and features.
Link Posted: 10/8/2012 1:16:26 PM EDT
Topic Moved
Link Posted: 10/8/2012 2:30:49 PM EDT
I have a PRO mounted on a S&W 16" with the fixed FSB and Magpul MBUS rear and it works fine.
Once you have the sight mounted you just use toe irons to put the dot on the tip of the front sight, you are now pretty well dighted in.
Using the Pro, you barely even notice the front sight.
Link Posted: 10/9/2012 7:38:11 AM EDT
Ok then, I will give it a try. I'm excited about the new Aimpoint.  I did my research,and it came down to Aimpoint. The price of the PRO is very attractive. I wanted top quality without needing a second mortgage to buy it.  It should serve me well for home defense and defending my property should bad things ever happen (pray that it won't). I just ordered a Matech rear BUIS. It has limitations, but I was attracted by the fact it's military issue, comes stock on LE6940s, and they are reasonable in price. I will let you guys know what I think.
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