Yes the Mag Express are .44cal pistol bullets and the sabots that come with them are made for .429 bullets. For the most part they should load good in most T/C rifles but I have seen some tight bores and T/C had a crappy bunch of sabots the put out a couple years ago and they are still in some stores. If you buy a box that has them call their Tech support number and they will send you some replacements. Interesting enough I have never had any problems with their bulk sabots loading well the only time I had trouble was the first batch of Shockwaves I bought.

Back to the Omega if it shoots anything like my Encore it will like bullets of .44cal to be over 250g weight for best accuracy. I buy the Hornaday 265g Interlock flatpoint and use bulk mag express or Harvester sabots with them. This is not a hollow point so I drive it pretty hard.