I first want to say than you Tim:I like the way the action break compared to old loose fitting ,The shim on the rear of the forestock 4 thousands did the trick.
I only have IMR powder on hand 4831 and 3031
4831 not bad 3031 a hole lot better I also found this new barrel will not shoot bullets seated 10 thousands off the land and groove
I did try a dummy round and let the action close and seat the 139 grain hornady bullet my C.O.A.l. 2.880
I loaded a few rounds both with 4831 and 3031 at 2.860 and the results were 3031 with 37.5 shot the best.I did have a few flyer's in the group but just like handi barrels 3 touching and 4@5 round climbed a few inches.
I went out to day and reloaded a few rounds at 2.800 and from the bench at 60 yards all 5 shots in or under 3/4" not bad,I also found the new barrel needs a little more pressure to lock up the barrel to action.
I just ordered a new decelerator pad for the rifle in .080 hope to soften the recoil a tad more