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1/22/2020 12:12:56 PM
Posted: 10/4/2007 8:02:09 PM EST
[Last Edit: 10/4/2007 8:03:14 PM EST by blake-b]
I have an LMT MRP with a Troy folding rear sight. It's pretty much sighted it but should the windage adjustment have it this far to the left? I'm new to ARs so I have nothing to judge this by and no one else I know has a Troy sight. The front sight is an LMT tactical front sight assembly.



Thanks...
Link Posted: 10/4/2007 8:03:20 PM EST
it's a bit excessive but still within normal limits.

what kind of front sight are you using?
Link Posted: 10/4/2007 8:06:03 PM EST
An LMT screw on... looks like the regular M4 style.
Link Posted: 10/4/2007 8:06:50 PM EST
[Last Edit: 10/4/2007 8:07:32 PM EST by Zack3g]
is it mounted to the rail? is it straight?

if the sight is true, and you are zeroed i wouldn't worry.

if it isn't, fix it.

Link Posted: 10/4/2007 8:14:48 PM EST
It's mounted to the rail and appears to be straight. I guess I'll get used to it. Thanks for your replies.
Link Posted: 10/4/2007 8:20:28 PM EST
That would drive me up the wall, within "normal limits" or not. There has to be a reason it isn't at least, a little more centered. Barrel improperly indexed, or maybe a canted front sight would be my guess. What if you need the windage adjustment you currently don't have with the sight like that?
Link Posted: 10/4/2007 8:23:29 PM EST
[Last Edit: 10/4/2007 8:23:52 PM EST by Zack3g]

Originally Posted By fishngrits:
That would drive me up the wall, within "normal limits" or not. There has to be a reason it isn't at least, a little more centered. Barrel improperly indexed, or maybe a canted front sight would be my guess. What if you need the windage adjustment you currently don't have with the sight like that?


the improperly indexed/over or under torqued barrel or out of spec front sight are the only options jumping out at me here.. he's using a LMT MRP which is a monolithic rail system, and the front sight is mounted to the rail.

Link Posted: 10/4/2007 8:24:30 PM EST

Originally Posted By Zack3g:

Originally Posted By fishngrits:
That would drive me up the wall, within "normal limits" or not. There has to be a reason it isn't at least, a little more centered. Barrel improperly indexed, or maybe a canted front sight would be my guess. What if you need the windage adjustment you currently don't have with the sight like that?


the improperly indexed/over or under torqued barrel or out of spec front sight are the only options jumping out at me here.. he's using a LMT MRP which is a monolithic rail system, and the front sight is mounted to the rail.



Word. I guess reading really is fundamental.
Link Posted: 10/4/2007 8:25:53 PM EST

Originally Posted By fishngrits:

Originally Posted By Zack3g:

Originally Posted By fishngrits:
That would drive me up the wall, within "normal limits" or not. There has to be a reason it isn't at least, a little more centered. Barrel improperly indexed, or maybe a canted front sight would be my guess. What if you need the windage adjustment you currently don't have with the sight like that?


the improperly indexed/over or under torqued barrel or out of spec front sight are the only options jumping out at me here.. he's using a LMT MRP which is a monolithic rail system, and the front sight is mounted to the rail.



Word. I guess reading really is fundamental.


either way, he should be fine.

that upper's just waiting for an eotech or an aimpoint or some other optic anyway
Link Posted: 10/4/2007 8:31:37 PM EST
[Last Edit: 10/4/2007 8:32:39 PM EST by fishngrits]

Originally Posted By Zack3g:

Originally Posted By fishngrits:

Originally Posted By Zack3g:

Originally Posted By fishngrits:
That would drive me up the wall, within "normal limits" or not. There has to be a reason it isn't at least, a little more centered. Barrel improperly indexed, or maybe a canted front sight would be my guess. What if you need the windage adjustment you currently don't have with the sight like that?


the improperly indexed/over or under torqued barrel or out of spec front sight are the only options jumping out at me here.. he's using a LMT MRP which is a monolithic rail system, and the front sight is mounted to the rail.



Word. I guess reading really is fundamental.


either way, he should be fine.

that upper's just waiting for an eotech or an aimpoint or some other optic anyway


Yep. I like to use flip up BUIS for my primary sights, especially the Troys, (I hate carry handles/A2 sights) if I don't have an optic on.
Link Posted: 10/4/2007 8:37:50 PM EST
The Mil-Spec for the M-4 Carbine states that the weapon should zero with the windage adjustment within +/- 5 clicks of the 0 position on the rear sight. Don't know how that relates to the position in your pic. The spec is published on the cover page of this Board.
Link Posted: 10/5/2007 2:41:01 AM EST
I took the CompM4 and 3X magnifier off to take the pictures.... I took some with the Comp on and the magnifier flipped to the side but it was too distracting.

I also emailed Troy to see if they have anything that might shed some light on it.
Link Posted: 10/6/2007 2:06:47 AM EST
Yeah, I would say it is in with in normal limits. I had a bushy dissapator that was wasy worse than that. My three AR's are sporting clamp on style gas blocks for that very reason. The Gas blocks that clamp on will generally let you get a mechanical zero.
Link Posted: 10/6/2007 5:19:32 PM EST
If both sights are on the same rail...

Just for S&G, reverse (right to left) the front sight and see if the front sight is what's causing your issue.

If not, try the same with the rear sight and see what happens.

This will let you know where the culprit is.

Whichever one you swap and see the greatest amount of windage required to correct will be the one at fault.
Link Posted: 10/7/2007 12:47:35 AM EST
I will try this next week when I go shooting.

I was thinking though that it might possibly have something to do with the barrel because it's basically free floated. If it wasn't seated correctly (due to machining or whatever reason) and was ever so slightly off to the right, that would cause the rear sight to be to the left in order to align everything. Is my thinking correct?
Link Posted: 10/7/2007 4:04:08 AM EST
I have the exact same issue, windage way to the left.

I just received a mid length parts kit from M and A Parts and they use LMT uppers. I have a free float YHM rail and a YHM detachable flip up rear BUIS on a LMT flat top receiver. The front sight is the standard attached M-16 front sight.

My guess is that the front sight / gas block isn't exactly strait. I plan on using an ACOG anyway and the iron sights are zeroed but it's still driving me crazy. Any idea on how to fix it?
Link Posted: 10/7/2007 8:52:45 AM EST
I discovered that my barrel is approx. 1mm to the right when properly torqued from the centerline of the MRP rails. That would explain why the rear sight is so far to the left in order to zero it at 50 yards. I was blaming the sights but they aren't at fault.

My question is now: Is this fixable and if so, how is it fixable?

AND

should I be this picky? I did pay A LOT for this whole rifle and setup...

Thanks
Link Posted: 10/9/2007 8:52:54 AM EST

Originally Posted By jhl72:
I have the exact same issue, windage way to the left.

I just received a mid length parts kit from M and A Parts and they use LMT uppers. I have a free float YHM rail and a YHM detachable flip up rear BUIS on a LMT flat top receiver. The front sight is the standard attached M-16 front sight.

My guess is that the front sight / gas block isn't exactly strait. I plan on using an ACOG anyway and the iron sights are zeroed but it's still driving me crazy. Any idea on how to fix it?


Paul at MSTN gave me the idea to shim the sight (front or rear) to give a mechanical zero. I can forward you the emails if you want. It sounds like it would be quite time consuming but I think I am going to give it a try. I am using a CompM4 and rarely is the rear sight flipped up but it's driving me crazy too!
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