Help with non-consistent sight picture

[ARFrog]

Being a total optics NOOBIE, I decided to start small with my first scope project and mounted a 9x32 Bugbuster on a Smith & Wesson M&P 15-22.



While I got everything sighted in OK, I seemed to be having issues with consistent scope picture. When I present the rifle, sometimes I have a totally black sight picture, sometimes only the left side curvature is black and sometimes I have a cross reticle with a ghost of a lower portion of the reticle in the lower right adjacent to the main one. With the non-consistent views I seem to be moving my head all over the place to get a clear sight picture which happens to begin with maybe 20% of the time.

Does this sound like a problem of distance between my eye and the back of the scope - perhaps it being mounted too close to the rear of the receiver- or is it an eye or eye training problem? I don't think it is a level issue because when I can see it I can hit the target appropriately.

Any suggestions would be appreciated.

[kcheung2]

It's hard to tell from the picture, but do you have the scope mounted within a pair of rings, which is then mounted on a riser, which is then mounted partway on the upper receiver & partway onto the handguard?

What you're describing is an inconsistent sight picture because you have poor (or nonexistent) cheek weld. You need to put your cheek in the same spot every time.

Another question: How did you determine that specific location for the scope? As in, why there and not 1/2 inch further forward or backwards?

[ARFrog]

In order to clear the iron sights, I have an additional rail sitting on top of the main picatinny rail ( partially on the upper and partially over the handguard) with sight mounts raising the scope above that.



Concerning placement, I had read that I needed to have it as far back on the receiver as possible. This was as far back as I could get it without removal of iron sights or extending LOP on stock. It appeared OK on the bench but is far from OK when holding it.

[kcheung2]

A few suggestions: get rid of the iron sights. You're not going to war with a .22 & a Bugbuster. If the scope breaks, put the gun back in your range bag, have a sip of gatorade, and then put it back in your car and drive home. Besides, they can't even be flipped up without removing the optics, and when you do remove the optics you'll likely lose zero.

Then get rid of both the rings and the riser. As it stands now, there are 5 points where things can go wrong, either by coming loose or being misaligned. Where the rings attach the scope (2), where the rings attach to the riser (2), and where the riser attaches to the upper(1). And for good measure, you added another point since the riser is bridging both the upper and the handguard. What if the handguard twists a bit?

Replace them with a good cantilever one piece mount, and have it mounted only on the upper. Aeroprecision & Warne gen2 are good inexpensive options, and a lot of people like the Burris PEPR mounts (although I think they're too heavy) There are obviously better options in higher price brackets. Don't worry about mounting height, the one piece mounts are set up for AR height.

I assume you set the stock to the proper LOP for your situation, and that you know how to get proper cheek weld that works for you. Keeping your cheek in that location, then place the scope where you get a proper sight picture. Looking through it, move it forward & back until the tube is a visible and clear (as in focus, not transparent) circle. The tube should not look like a blurry circle. The eye relief (distance between your eyes & the scope) should be about 3-4 inches. Actually the Bugbuster has a pretty forgiving eye relief so there's wiggle room. That's where your scope should be placed. It doesn't need to be as far back as possible, it needs to be placed where it fits you. For many people it means the scope back is directly over the charging handle, but everyone is different.

To confirm you have the correct location, set your zoom to the smallest (3x), set the focus to closest (3yds), and every time you present on target (keep gun pointed in safe direction, unloaded, etc) you should have a good sight picture. Then increase the zoom & distance & it should be the same.

If you're still getting a black side curve or all black, that means your head is off center, either left or right. Work on getting a consistent cheek weld. It may take some work, first time I used a scope I was holding my head in all sorts of weird locations & getting the same problem with the scope picture getting blacked out.

[HK Dave]

Gave you tried moving your head forward or backward to see if it makes it easier to get an entire picture?

[LCU1670]

When I was in the Army to get people to get a consistent sight picture, we would have them sight up with their nose touching the charging handle, then adjust scope to that.

[arrowshooter]

Your scope is mounted way high and you need more of a "chin" weld to get a consistent sight picture. As suggested, lose the irons and riser, or add padding to the top of the stock until you get the proper cheek weld.

[ARFrog]

Thanks all for your helpful suggestions.

I'll make some changes as follows:

- loose the iron sights (after I get this working maybe I'll try and add back some 45 degree sights, if needed.)

- loose the rail and mount either the scope rings or a new cantilever one piece mount/rail directly to the main picatinny rail

- mount the scope over the only the upper/receiver portion and go for the best sight picture irrespective of how far back/forward. This also should include attention to cheek weld issues.


... scope 2.0 to follow

[sonofeugene]

Gave you tried moving your head forward or backward to see if it makes it easier to get an entire picture?

This.

OP: From your description, you likely have the scope mounted too close to you. It might be handy to have a friend help you. Loosen the scope so that it can be slid back and forth. You may have to have your friend keep it from falling off. Get yourself into your shooting position with a good and comfortable "weld" of your cheek to the stock. This will be the position of your head on the rifle every time you shoot it. Then have your friend move the scope back and forth until you get a good sight picture without any of the picture blacked out. You'll find that there's only a short range of distance where the picture is ideal. Find the middle of the range. Of course, you may have to adjust your head up or down a bit which will tell you how high to make the scope mounts.