I don't have an Encore, but the guys I know who do have had better luck with conicals (as far as best accuracy) by removing the QLA. As in having the end of their barrels shortened to the rifling. There is really only one way to find out if your rifle likes them or not. You will want to slug your bore to find the exact diameter to order for the T/C though, since there is variations in their bore diameters. My T/C is a .54, but I have other 1-28 .50 calibers (Knight &NEF) that shoot conicals very well. My Whites in both .451 (1-20) and .504 (1-24) have the optimum twist rate for the long heavy conicals but the 1-28's will do well with 430-460 grainers.
You will want to order the exact diameter of your land to land measurement for slip fit loading with slight engraving and best accuracy IMO. Dan, at Bullshop will size them to any size you want, but be sure to order pure lead.