This topic is for PS90 Triple Rail owners looking for a cheap but functional optic or scope. I suppose tops on the list would be the freebie C-More Reflex sight, as you can't beat free. However, I don't have mine yet and can't evaluate/review it. But I did find a low cost but fully featured scope that I highly recommend.
http://www.ncstar.com/store/scripts/prodView.asp?idproduct=36
NcSTAR Mark III Tactical Scope 2-7x32 "P4 Sniper" #STP2723G
Variable magnification 2X-7X
32mm objective
Sniper cross hair ranging reticle
Variable intensity red or green illumination of reticle
Coated lens
Range dial (for .223)
Quick release mount
2.9" eye relief
Compact size
I paid $139 out the door, but have seen it for $115 online but you would have to pay shipping and maybe tax. I like trying out scopes, so checking it out before paying a little more was worth it to me.
First of all it looks the part with its compact size, over-sized objective, and an ACOG-like slant on the sun shade. It adds to the top profile for more of a sniper look than a busting-down-the-door look. The scope fits the PS90TR very well with its compact size and eye relief. I have it set back one notch before the rearmost notch on the rail so there is some leeway. Cheek weld is excellent, not too high or too low.
The magnification is fantastic if you have aging eyes like me. Even if you don't need the magnification for aiming (I do), the magnification allows you to see the tiny 5.7 holes in the target downrange. With the mag turned up to 4X I wwas able to shoot several one hole clover leaf 3 shot groups at 25 yards (maximum distance at my indoor range). And I could varify the cluster without having to draw the target back. The over-sized 32mm objective gather lots of light with a huge field of view. The sight picture is so much better than the white or black reticle PS90 optics.
With the illumination turned off, the reticle is a sharp black standard ranging cross hair that I use 90% of the time. You can also turn the reticle illumination on in either red or green for a very high tech sight picture. It uses a standard lithium CR2032 flat battery size. One lithium battery comes already installed and another is supplied as a spare. The seller said the batteries last a very very long time, as long as you remember to turn the power of before storing the gun. The illumination is very bright and I never have to crank it above the lowest of three settings. By the time you have to crank up the intesity, I imagine it would be a good indication that you need to change battery. The battery is under the intensity dial cap on the left side; changing the battery would less than 30 seconds. The beauty of it is that it works like a normal tube scope with a crisp black cross hair reticle when there is no power, so no back up sight is needed. Again, most of the time I don't have the power turned on when shooting as the unilluminated reticle offers plenty of sharp contrast.
The quick release mount is excellent and works like a bicycle wheel quick release. The cam and long lever can exert plenty of leverage for a secure hold, in fact the manual says that it should not take a lot of force for a secure hold. With recoil, the cross rod on the mount will settle against the back of the notch you select, so it is best to clamp the scope so it rests against the rear of the rail notch. the quick release has a set screw and lock nut to hold your tension setting. Follow the instructions carefull to set it properly and to avoid stripping the screw/nut. If you have doubts about the strength of a quick release, know that quick release levers on the hubs of bicycles can easily support a 250 lbs rider hitting pot holes without the wheel slipping. You might dent a rim, but the wheel will not slip in the fork.
Warning: because of the swing out quick release lever, I don't think this scope will work with a standard PS90 (non-triple rail) with TROS rail.
The great thing about the quick release is that it holds zero. After I sighted in, I decided the move the scope one notch on the rail for better eye relief. With the quick release feature this only took 5 seconds. I expected to have to adjust zero, but the next group was another one hole group dead center on the bull's eye.
The scope can be zeroed with no tools. There is a cap on the elevation adjustment that comes off with a coin. The adjustment itself can be done by hand. There is dialable bullet drop compensator (100-500 yards) on the outer cover of the elevation adjustment that is nice, but is set for .223 so it may have limited use for the 5.7 round. Once you set the windage, you can use an allen wrench to remove its cover and rotate the cover to zero. That way you can tell at a glance if it has been turned and can set it back to zero easily.
So for a bargain basement price, this low cost scope has lots of features and allows me to shoot some very tight groups with my PS90 TR. I highly recommend it.

http://www.ncstar.com/store/scripts/prodView.asp?idproduct=36
NcSTAR Mark III Tactical Scope 2-7x32 "P4 Sniper" #STP2723G
Variable magnification 2X-7X
32mm objective
Sniper cross hair ranging reticle
Variable intensity red or green illumination of reticle
Coated lens
Range dial (for .223)
Quick release mount
2.9" eye relief
Compact size
I paid $139 out the door, but have seen it for $115 online but you would have to pay shipping and maybe tax. I like trying out scopes, so checking it out before paying a little more was worth it to me.
First of all it looks the part with its compact size, over-sized objective, and an ACOG-like slant on the sun shade. It adds to the top profile for more of a sniper look than a busting-down-the-door look. The scope fits the PS90TR very well with its compact size and eye relief. I have it set back one notch before the rearmost notch on the rail so there is some leeway. Cheek weld is excellent, not too high or too low.
The magnification is fantastic if you have aging eyes like me. Even if you don't need the magnification for aiming (I do), the magnification allows you to see the tiny 5.7 holes in the target downrange. With the mag turned up to 4X I wwas able to shoot several one hole clover leaf 3 shot groups at 25 yards (maximum distance at my indoor range). And I could varify the cluster without having to draw the target back. The over-sized 32mm objective gather lots of light with a huge field of view. The sight picture is so much better than the white or black reticle PS90 optics.
With the illumination turned off, the reticle is a sharp black standard ranging cross hair that I use 90% of the time. You can also turn the reticle illumination on in either red or green for a very high tech sight picture. It uses a standard lithium CR2032 flat battery size. One lithium battery comes already installed and another is supplied as a spare. The seller said the batteries last a very very long time, as long as you remember to turn the power of before storing the gun. The illumination is very bright and I never have to crank it above the lowest of three settings. By the time you have to crank up the intesity, I imagine it would be a good indication that you need to change battery. The battery is under the intensity dial cap on the left side; changing the battery would less than 30 seconds. The beauty of it is that it works like a normal tube scope with a crisp black cross hair reticle when there is no power, so no back up sight is needed. Again, most of the time I don't have the power turned on when shooting as the unilluminated reticle offers plenty of sharp contrast.
The quick release mount is excellent and works like a bicycle wheel quick release. The cam and long lever can exert plenty of leverage for a secure hold, in fact the manual says that it should not take a lot of force for a secure hold. With recoil, the cross rod on the mount will settle against the back of the notch you select, so it is best to clamp the scope so it rests against the rear of the rail notch. the quick release has a set screw and lock nut to hold your tension setting. Follow the instructions carefull to set it properly and to avoid stripping the screw/nut. If you have doubts about the strength of a quick release, know that quick release levers on the hubs of bicycles can easily support a 250 lbs rider hitting pot holes without the wheel slipping. You might dent a rim, but the wheel will not slip in the fork.
Warning: because of the swing out quick release lever, I don't think this scope will work with a standard PS90 (non-triple rail) with TROS rail.
The great thing about the quick release is that it holds zero. After I sighted in, I decided the move the scope one notch on the rail for better eye relief. With the quick release feature this only took 5 seconds. I expected to have to adjust zero, but the next group was another one hole group dead center on the bull's eye.
The scope can be zeroed with no tools. There is a cap on the elevation adjustment that comes off with a coin. The adjustment itself can be done by hand. There is dialable bullet drop compensator (100-500 yards) on the outer cover of the elevation adjustment that is nice, but is set for .223 so it may have limited use for the 5.7 round. Once you set the windage, you can use an allen wrench to remove its cover and rotate the cover to zero. That way you can tell at a glance if it has been turned and can set it back to zero easily.
So for a bargain basement price, this low cost scope has lots of features and allows me to shoot some very tight groups with my PS90 TR. I highly recommend it.