I have no experience with Sightron but have read good things about them on various boards. I believe they are made in Japan.
Your price limit ($450 )limits you greatly in your options and the Sightron does seem to be excellent value for money. It has 1/8 th clicks, Target Turrets and hight elevation range at about 40 MOA.
Other scopes to consider are
Burris Signature 6-24x44 A/O, Mil-Dot, Matte, Target Knob $499.95. Has small adjustment range at 22 MOA
Bushnell Elite 4200 6-24x40 A/O Matte Finish with Mil-Dot Reticle $389.95. Lacks Target Turrets and has small adjustment range of 26 MOA. Excellent glass and solid design.
Bushnell Elite 3200 10x40 Matte Finish, 1" tube, Mil-Dot Reticle $189.95. Has 1/4 MOA clicks, large adjustment range 78 MOA, but lacks AO and high magnification. Has fast focus and nice glass.
The reason I mention the little 10x40 is so you could consider purchasing this, and use it while saving for a 30 MM tube Leupold, Burris Black Diamond or IOR Valdada which will meet the full specification you require, give you a large adjustment range, great glass, side parrallex adjustment and a lifetime of great service.
Ian M reviewed the 10 x 40 on this forun at
All prices are from www.riflescopes.com.