This is one of the Saiga 20 Kushnapup guns we have done for clients.
Almost anyone can take a stock Saiga and put it into a Kushnapup stock for about $245.00 and sell it for $1100.00 or thereabouts.

BUT if you want the finished product to shoot low brass ammo as well as it shoots high brass ammo, to be extremely reliable and with a smooth action and if you want a shorter gun but still legal so it is great for indoor home defense, then you need what we have done to this gun, done to yours.
Coming down the hall at night with a long shotgun and trying to turn around is not easy with the standard barrel length of 19" plus a 2" brake screwed onto the end of it.

When we build a gun we try to take into account how it will be used and make the necessary changes to optimize that gun for it's intended purpose. To that end we have done almost the same performance options that we have done on most of our other more expensive guns. BUT we have left off the cutting and brazing of the brake to save some money on the build.

First, since this model uses a basic factory standard gun to start with, we pulled the Fire Control Group and polished and re-profiled it. We also polished and re-profiled the bolt and carrier to improve smoothness as well as reliability and we buffed the rails. Next we jeweled the bottom of the carrier to hold oil better.
We then did our gas port work by enlarging all 4 ports and modifying the gas block itself as well. Then we installed a new, modified gas knob that works with the port work we just did as a Plain Jane after market gas knob will not function correctly. We changed the recoil spring and buffed out the rails as well. Everything done to enhance reliability and performance and making the gun a smoother gun to operate, charge, and shoot.
We also drilled and tapped the gas block and added a top rail for a red dot (red dot optional extra) as the factory sights become useless in this style of Saiga shotgun
With this rail you need a taller red dot such as an Eotech or a Burris FastFire on an AR Riser. We also have a taller rail that can be installed that sits about 1/2" higher but the one currently on the gun looks sleeker.
We then added an SGM butt pad to the rear.
And we added a copy of a Bulgarian brake to the threaded muzzle.
The gun is a blast to shoot and runs most low brass as well as high brass ammo without a hiccup. We test these guns with a variety of low recoil ammo.
For an independent review by one of our clients who bought this gun in a 12ga. go here:

http://www.thetruthaboutguns.com/2014/12/daniel-zimmerman/gun-review-saiga-custom-kushnapup-2/