Since 2006 the Saiga-12 has seen increased popularity by competitive and recreational shooters. The ability to rapidly reload by changing magazines rather than stuffing shells in a tube is the source of the Saiga-12′s popularity. There currently is no other detachable magazine fed shotgun commercially available for civilian purchase in the United States.
One thing most people will immediately notice about using the Saiga-12 is that it does not load as easily as a traditional AK-47 pattern rifle. While the Saiga-12 is based on the AK receiver and action it is important to remember it is not the same as a regular AK. Due to the difficulty loading a full magazine with a closed bolt, later model Saiga-12s included a manual bolt hold open device. The shooter could activate it by pulling back on the bolt handle and pressing up on a tab located by the trigger at the same time. While this did make loading easier, it also slows down the loading process.
I began using the Saiga-12 competitively in late 2006 and initially used the manual hold open for reloading. I used this technique until I wore out my bolt hold open in the middle of the 2008 Rocky Mountain 3-Gun match. The bolt carrier had gradually cut a channel on the side of the bolt hold open and was allowing the bolt to slide past. Out of necessity I learned how to load on a closed bolt during the match. Without practice, my technique was less than ideal.
After that match I found that the factory fire control parts were well worn in addition to the bolt hold open. I decided to do a pistol grip conversion to that gun, since the fire control needed to be replaced anyway. I had a replacement bolt hold open, and installed it as well. I quickly discovered that leaving the bolt hold open in place with standard AK fire control parts prevented the hammer/trigger spring from fully expanding to the sides of the receiver. The right hammer spring leg could jump out of position and prevent the trigger from resetting all the way, resulting in a dead trigger. I believed that removing the bolt hold open was a necessity for the sake of reliability. I also began to work on my reloading technique so that I could consistently seat the magazine without having the bolt locked back.
Step by step how to load on a closed bolt
1) Carry your magazines shells up. You should do this anyway as re-orientating a Sagia-12 magazine carried shells down is not ergonomic or time efficient.
2) Accept that the Saiga-12 will not load the same exact way as an AK-47. The angle of entry for the magazine into the mag well is much higher than with an AK-47.
3) Consistently grab the magazine in the same location every time.
4) Seat the tab first
5) Push forward hard while rotating up to keep the tab seated. Failure to do so will allow the magazine to pop out.
6) When the magazine is rotated into position you are compressing the shells down into the magazine. It may be easier to load with 9 in a magazine rather than 10 consistently. I prefer to download to 9 for this reason and the gun seems to more reliably feed the first round out with 9 + 1 in the chamber than 10 + 1 in the chamber.
Having used this technique for a few years now, I believe that the bolt hold open devices and bolt modifications are unnecessary for reliable and efficient reloading. The fewer modifications your Saiga-12 has, the more reliable it is likely to be long term.