I just purchased the Umarex hK mp5 sd .22 LR and I would like to get a red dot sight for it, does anyone have any recommendations based on their experience with their own SD? I also need to get a rail to mount it. Any recommendations, I am looking to spend as little as possible but am willing to pay for performance. I read the other posts on this but its still not clear to me which rail to purchase and which red dot to purchase. Help would be very much appreciate. Is there a place that sells 25 rd magazine rebuild kits or parts?