I would never think that a 400 FPS plastic BB can shoot out a glass aiming sight. After all, the claim is that a plastic BB is much softer than a glass BB. But with so many Internet reports of glass sights and scopes being shot out in airsoft games, you have to take it seriously.
For anyone who is skeptical on whether BB's can break the red dot sight glass, take a look at the following photograph.
I took the photo after my friend's head-up red dot sight got shot at an indoor CQB airsoft arena. I had been using the microscope slide sight protector (see below) and a Aim Sports Lens Protector (see below). Therefore, my red dot sight hadn't been damaged yet. But my protectors had been shot out many times.
This DIY article shows you how to make your own economical sight/scope protectors. And offers some solutions to keep your sight as safe as possible.
Airsoft3D now makes the stainless steel red dot sight protectors. They come in various patterns--honeycomb, grill, etc.--and sizes; pretty much fits any scope on the market. They can also make custom sizes, so if you have a special scope, you can contact them to provide a kill flash for you.
Airsoft3D Grill Red Dot Sight Protector provides high visibility.
Airsoft3D Honeycomb Kill Flash provides great look and excellent functionality.
The red dot sight protector are specified by outer diameter. So you measure the diameter of your scope and buy the right size for it. Then you either glue it on your scope or tape it on. Black hockey tape is probably the best for this purpose. See "Related Links" below to get a roll of black hockey tape.
The stainless steel kill flash and red dot sight protector are super strong. They are practically indestructible from Airsoft BB's. So you attach it to your red dot sight once and pretty much forget about it. You never have to replace the protector.
Transparent polycarbonate sheets are just like plexiglass. But there are two improvements over the traditional plexiglass. One, polycarbonate is extremely clear. It transmits light almost as well as glass. It's hard to tell a difference when the two are placed side-by-side. Two, polycarbonate is extremely resistant to impact without cracking or breaking. These two traits makes it an very good sight protector.
Polycarbonate, also known as Lexan, is available at your local home improvement stores--Home Depot, Lowes, etc--for only a few dollars a sheet. You'll also need to pick up a cutter (same as plexiglass cutters), if you don't already have one. Cut polycarbonate in the same way you cut plexiglass, which is to score it with the cutter and then snap it apart.
Once you cut it down to the right size, the next question is how are you going to affix it to your red dot sight? If you take good care of your red dot sight, then you can permanently glue the clear plastic to the front and back of the sight. In the photo below, I have used J-B Weld to permanently join the two.
The polycarbonate is resistant to scratches, even after impact by airsoft BB's. Therefore, if you avoid scratching the clear plastic, it should work on and on with very little maintenance.
When I installed the Ultimate Arms Gear Tactical 4 Reticle Sight (JH400) onto my APS ASR106 Mini Patriot M4, I really didn't want it to get shot out on the field.
Now, I can get an airsoft sight protector (see Related Links below). But it's $15 every time it gets shot out by an airsoft BB. You might as well get $10 red dot sights instead. And my guess is the plastic protector will blur the sight vision.
I have a better idea... glass microscope slides. You can buy 72 glass slides for $5 to $10 (see photo below). Every time one slide gets shot out, you just replace it with another one.
The microscope slide is made out of clear glass (see photo below). And is usually made uniformly in order to provide the best visibility for scientific research purposes. Make sure you don't get the frosted version.
The microscope slide is just big enough to cover the Ultimate Arms Gear Tactical 4 Reticle Sight (see photo below). In fact, one slide has enough surface area to serve twice. If your sight is bigger, than you can use multiple slides.
Use a glass cutter (see photo below) to score the glass. After scoring the glass, snap the glass slide in two. Before you snap it, make sure you wear goggles.
After cutting the glass to size, I tried it on the sight. I taped the glass slide to the front of sight. Turning on the red dot, I found that the glass slide doesn't throw off the holographic red dot. Perfect. The microscope glass was so uniform, there was no distortion in the vision. It worked better than I expected. The question, then, was how to mount it permanently, but not so permanent that it can't be replaced.
The answer is white glue. White glue on the four corners of the microscope slide (see photo below) makes it easy to fix to the sight. It excretes no fume to fog the sight. It drys almost clear, so that it doesn't stand out. A bit of finger nail can usually remove it from most surfaces. At worst, a little bit of water will solute it.
I took the sight with microscope slide protection to an indoor CQB field this past weekend. It worked beautifully. Neither the microscope slide nor the sight got shot out. I don't know if it was ever hit by a BB. But with it, I wasn't afraid to stick the rifle out at the enemy.
After a indoor CQB game, I noticed that the protection glass is gone. I remembered at one time during the night, I heard a loud crack coming from my gun. I didn't really think much of it at that time, thinking a pellet hit my gun. But while packing up my equipment, the protection glass was no longer on the sight. It came clean off leaving no glue residue behind (see photo below).
I don't know if the hit shattered the protection glass slide or just popped it off the red dot holographic sight. But I was glad it hit the protection, rather than the sight. Now that I know the noise of the hit, I will keep my eyes out next time.
I now have more examples of the microscope slide protection being broken by BB's. The photo below is a classic example of a bullet hole in glass. Except this time, it's the BB breaking the microscope slide glass protector.
I have also made some tests and shot a video of different FPS airsoft guns shooting microscope glass slides. It answers the question, "Will Airsoft BB Break Glass?"
I already had the other half of the glass slide ready to go. Gluing it on was a piece of cake at home. But it made me wonder what I should do the next time it happens. I was very fortunate that no one hit the sight again that night. And this is the only time someone hit the sight after playing two nights with it.
But it doesn't mean I can't be unlucky enough for someone to hit it twice in one night. So here are some ideas.
One: Use two guns with two sights. You can't have two sights ready to go, because the sights have to be sighted in on the gun. When you switch sights, there is no guarantee that it will be dialed in. The best scenario is to have two guns with two sights. When one protector is smashed, switch to the second gun.
Two: Carry Aim Sports Lens Protector (see "Related Links" below). When the glass microscope slide is shattered, mount the Aim Sports Lens Protector for the next round. After getting home, you can glue another glass slide onto the scope and remove the airsoft sight protector.
Three: Remove the sight after glass slide shatters and use iron sight. This is the most economical solution. But also the most inconvenient. Once you removed the sight, you'll have to dial it back in after mounting it. But is a good solution if you are unlucky twice in a row using one of the two solutions above.
Four: There are a number of red dot scopes on the market that comes with transparent lens protectors. I have been using them on the airsoft field. They work great and prevented the red dot sights from being shot out. But after years of use, airsoft BB's did manage to crack the transparent lens protectors. Read our review of these scopes:
Five: Use the stainless steel sight protectors and kill flash shown above in the article. They are virtually indestructible. No need to worry about shattering the red dot sight again.