Co-Witnessing Sights Issue

[Rastoff]

I think we may have a disconnect with regards to what "co-witness" means.

Co-witness means that you can use the irons without removing the optic. It does not mean that you use both at the same time.

It logically follows that if you were to use both at the same time, they would coincide with each other. This means that if you have the optic on and the front sight centered in the rear aperture, the red dot/reticle will be sitting right on top of the front sight. It would have to in order for the bullets to hit the same POI.

cypher,
I believe you, but it shouldn't happen that way. Of course you didn't mention the precision with which the sighting systems allow you to deliver rounds to the target. If you're saying that you get 1/2MOA with both sighting systems, and they don't line up with each other, then I'd have to see that.

Is it possible that you're misaligning the irons just a little when you shoot?

 

[Rastoff]

This is a great video on co-witnessing.

 

[ChattanoogaPhil]

Let me know the next time you are in Dallas... We can go to the range and you can shoot my rifle and see. My red dot does not sit perfectly centered on the front sight post... it sits off to the right edge of the post.

Shoot with irons and you will hit. Shoot with dot, and you will hit.

Okay.... but I suspect you are experiencing what was mentioned in my prior post.

Either you are moving your head from the irons to the optic experiencing parallax, or are aiming the dot off center of the target to keep the rifle in the same position of aim as with irons. Otherwise, if you are shooting center of target with your irons, how would you move the dot to center of target without moving the rifle and thus changing aim?

I suppose a person could have an astigmatism that so distorts the dot they don't know where it is really is. IIRC, A2 front sight post represents about 12moa in width. Really, the dot can't be that noticeably off FSP center without being pretty far off aim. To be 50moa off that would be the width of about four FSPs

Or Rastoff could be right that you aren't aligning the irons properly to begin with.

 

[redwood0_7]

Here is the way I did mine. Sighted in iron sights. Mounted red dot on rifle. Fold down iron sights. Sighted in red dot. Only use one sight at a time. IMHO once red dot sight is on rifle iron sights become back-up only in case optics go off, say from dead battery.

 

[cyphertext]

Misalignment could be possible, parallax could be possible... cheap red dot could be possible as well.

I played with it some this afternoon. I have a Millet Multi-dot, meaning I have 4 sizes of dot to choose from. I typically shoot with the smallest dot setting, and if I look through my sights, the right edge of the red dot lines up with the right edge of my front sight post. As I click through the sizes, the dot appears to move to the left as it gets larger. On the largest setting, it is fairly well centered...

Now I have to go shoot to see if it held zero from changing dot sizes.

 

[dragon011]

I tried to take a photo of my sight pic but could not do a good job. So I attached a photo I made to give you a better idea. The blue dot was where the tip of my front sight was when looking through the rear sight. And yes, prior to mounting it I was hitting near the center at 50 yds just as I did with my scope even though it looked like this. This was probably the best visual I could give you for now. Thank you.

 

[Rastoff]

dragon011,
With all we've talked about so far, and looking at those pics, I honestly believe you have a defective scope. It looks like it's mounted properly. The only thing that could account for the discrepancy is a misaligned prism in the scope.

Call Vortex on Monday and I'm sure they'll take it back, no questions asked.

 

[dragon011]

dragon011,
With all we've talked about so far, and looking at those pics, I honestly believe you have a defective scope. It looks like it's mounted properly. The only thing that could account for the discrepancy is a misaligned prism in the scope.

Call Vortex on Monday and I'm sure they'll take it back, no questions asked.

Just FYI...I called Vortex today and explained the issue. The person who was helping me agreed that what was going on was little strange and immediately sent a Fedex shipping label saying they will inspect it and replace it if there is something wrong. I shipped the scope today so I should get it back in few days. Will let you know what they said about it.

 

[Vulcan Bob]

I know that this is not relevant to the OP but I found that the whole co-witnessing thing to be distracting to me. I found the off set BUIS to be less distracting than having both sights in view at the same time. Guess it all comes down to what works for you!

 

[dragon011]

I know that this is not relevant to the OP but I found that the whole co-witnessing thing to be distracting to me. I found the off set BUIS to be less distracting than having both sights in view at the same time. Guess it all comes down to what works for you!

I would not use both sights at the same time either, but need to be sure that if i have to remove the optics for some reason i can hit the target using my iron sights. I could do this now, but the optic's zero is not a true zero...and i prefer to have both sights with the same zero.

 

[dragon011]

Well...today I talked to Vortex technical person who was servicing my Spitfire 1X prism scope and he claims it was not defective. We talked again about the co-witnessing issue and two different zeroes and he said that, because this is a prism scope, it should not be used at the same time with iron sights, because of the potential distortion of the front sight. Next, he said that both sights should be sighted in separately. We also agreed that co-witnessing these two sights is possible but useless, since they would work only if used together, but iron sights would be out of zero if the scope was taken off. So...until someone else brings some other valid argument, I settled on zeroing both separately and using my scope only while disregarding co-witnessing. If I ever have to use iron sights I will just take the scope off. They shipped it back today so I will have it at the range in about a week. Thank you all again for your help with this issue.

 

[ChattanoogaPhil]

I would have told them to keep it.

If you're going to have a 1x optic that isnt a 1x optic and can't be used with iron sights, then it might as well be an adjustable like 1-4x. Other than being able to focus the reticle for an astigmatism, what is the reason to buy this optic?

 

[Rastoff]

Yeah, I too no longer see the value in this scope. Return it and get something else.

I have a Hi-Lux CMR 1-4x24 that is really nice.

 

[dragon011]

This is the final update...

I received a new Vortex Spitfire 1X prism scope and repeated the zeroing process...this time I mounted the scope with torque wrench to eliminate mounting error possibility as well as paid close attention to marksmanship fundamentals and consistent cheek weld when zeroing my iron sights.

When I sighted both in I have achieved almost identical results shooting at reduced size silhouette target at 50 yds using Federal .223 55 gr ammo. The attached photo is shot with the scope on (forgot to take the photo where I shot with iron sights...but it was almost identical after few clicks adjustment for windage and elevation).

However, when I looked through my rear sight through the scope, the tip of my front sight was still sitting about 30 MOA to the left from the center of my scope (see the photo where green dot represents the front sight).

I was told buy Vortex about the possibility of distortion of the front sight when looking through the prism scope and was advised that they should both be zeroed independently. However, they said the scope was deigned to be used together with the iron sights....How???

Anyway, I decided to keep it simply because it does a great job as an alternative to classic red dot and is much smaller and lighter than 1-4X scope with wider field of view...If I need to use my iron sights I will just take it off...Also, I have no intention to shoot it past 100 yds.

So...this is it...I hope you guys had a nice weekend...I sure did!

 

[ChattanoogaPhil]

Great follow-up. I'm sure it answered a lot of questions for those considering this optic.

 

[Rastoff]

Thanks for the follow up. I'm glad you're happy with the scope, but I'm just as curious as you as to why it looks that way. I've never heard of the scope causing such tremendous parallax error.

I may have to go buy a prismatic scope just to check it out.

 

[NiteGoat]

Thank you for your replies. Here is some more info...The scope came with the base that should do lower 1/3 co-witness. I zeroed in my irons at 50 yds before putting on the scope. When i zeroed in the scope at 50 yds and looked at co-witness pic the center of the scope was to the right from my front site by alot. Now... i understand that i could just bring the center of the scope to co-witness as they should... but that would probably get me off the paper because of almost 50 MOA difference.

I was thinking about it some more and what i concluded is either the scope is deffective or i screwed up by just tightening the base screw with my fingers since i didnt have a wrench. It seemed tight and the scope was not moving ...but under the recoil... it is possible...Could this actually cause this huge discrepancy between two zeroes?

Is it possible that you mounted your sight backwards? I know some people (professional shooters) who have done that with this particular sight. It happens.

 

[TxM&P9]

Is it possible that you mounted your sight backwards? I know some people (professional shooters) who have done that with this particular sight. It happens.

Problem has already been solved. There was no problem to begin with. I was surprised when I came upon this thread that NOBODY knew how prism sights worked. The one guy on the first page that did know, nobody acknowledged him. Lol

 

[5point5sixGUY]

^
Use blue 242 thread locker, not red 271.

Loctite Threadlocker Blue 242 is designed to lock and seal threaded fasteners to prevent loosening from vibration.

Loctite Threadlocker Red 271 is designed for the permanent locking and sealing of threaded fasteners.

 

[WVSig]

This thread is 2+ years old and has been resolved. The new member who brought it back to life gave a long and some what incorrect response, "red" loctite as 5point5sixGUY pointed out is not the right product for the job.

Maybe we should loc this one up.... LOL