Just started playing with mine on a serious note this past weekend. In some rather loose preliminary testing last year it showed the best promise with the 120gr loads using Ramshot Magnum.
Mine however was built from the start to shoot the heavier bullets. I used a 1-9 Broughton 5C 4-1 Heavy Sporter in 28". When it was chambered I had a bit extra added to the throat to allow for the bullets to be seated out a bit and give a little more room in the case and jump on the bullet. I was looking to get the best velocity from the heavier bullets and to try and keep pressure a bit lower on top end loads, and hopefully keep them a bit tighter at some longer ranges. I figured that I would just stick to weights above 110 with this one, and see how it does. I would rather have the added BC, and SD for the feral hogs we shoot than the speed of the lighter weights.
The standard version I have simply loves RL-22, and I considered looking at it with this one as well, but in testing last year, it was showing inconsistent velocity and wasn't grouping nearly as well as what the Magnum does at any load.
Good luck with yours, and don't pass up a chance to try the Magnum if you have access to it, it has show to be VERY consistent in mine, but might be a bit slow for the lighter bullets. In the first link below my sig are a couple of pic's of the rifle and the two hogs I dropped with it last weekend. It was a fun time to say the least., well other than the cleaning part. Sure made for a good supper though on Saturday evening. Nothing like fresh BBQ ribs.