The Nerf Recon cs-6 is a favourite blaster among a ton of people, including myself. There is one problem with this blaster that I find to be quite annoying, and that is that the way you cock is to pull back on the top then push it forward again. Not a big issue if you have nothing attached to the top rail, but if you have a scope or light on the top it gets pretty awkward. My solution is to give it a bolt handle on the side, which if you have experience it taking apart a recon, a spare bolt handle from a longstrike or longshot, a small nut and bolt and a drill, is extremely easy!
the nut and bolt, and the nerf bolt. make sure the head of the bolt is small so that it doesn't rub on the sides of the groove in the yellow casing.
Start by taking the case off the recon, but leae the slide part on for the moment. also undo the 2 screws on the bolt you plan to use and take the centre out. Make a mark where to drill, it needs to be in the groove where the plastic peg of the grey case already slides. Take the grey case off and drill the hole very close to the same size as the bolt. Next sand down the top of the inside part of the nerf bolt. The amount you sand it down is slightly less than the thickness of the nut you're using. The When you put the nerf bolt back together, slide the bolt you're using through the inner part, wind your nut on and then screw the nerf bolt back together, then unscrew the bolt. the idea is that when you put the bolt back together it will compress down on the nut and hold it in place so that you can screw the bolt in from the other side of the grey case. If you sand down too far, you can use a washer.
Now, poke the bolt through the hole you drilled, and thread the modified nerf bolt on until finger tight. flip the case over and tighten the bolt with the appropriate tool while holding the nerf bolt, until very tight. Reassemble your new bolt action recon and test. If it is jammed or not smooth enough, take apart again and grind the head of the bolt down or use a smaller headed bolt. And that's it!
(Somehow i neglected to take a photo of the assembled blaster, but i will add that at a later date.)