Read through this posting a couple times. Recently I bought the 50 cal LR-X (Nov 7 2022), I also have an Inconsistent bore diameter. Bought the Thor bullets sizing pack, .502 is perfect fit for the first 12"-18" of the barrel, then it drops down VERY easily down the rest of the barrel. I don't feel safe shooting full bore Thor conicals because of how little pressure the bullet has seated over the charge. The LR-X is a Very nice gun, If the bore was more consistent it would be absolutely perfect! I picked the LR-X because of the Nitride/Ceracoat treatment, free floated barrel, ease of takedown/cleaning, modularity for hunting colorado and western states.
I absolutely will not be polishing a $649 brand new rifles barrel and hoping it solves the bore inconsistency issue. I don't want to mess with the internal barrel finish and also end up with Inconsistent rifling.
I have sighted in with 270gr elr powerbelt using 120gr of 777 mag pellets and federal 209mz. Pretty happy with the accuracy of this load, and the powerbelt seems to retain an acceptable fit throughout the bores length. All sabots, the Bore Driver, and powerbelt bullets seemed to fit well throughout the bore. Part of my focus was on out of state elk hunting where sabots, and in some places, pure lead or no plastic is required. My goal is to set this rifle up to hunt in any state for any game. I feel I can accomplish this, but it may take a different bullet selection than I anticipated. There are a lot of different bullets out there!
I haven't gotten into much load development yet, muzzy season starts in MN here on the 26th. I picked a bullet, sighted in, here we go. I have 9 different bullets, 4 different primers, and 5 different powder/pellets to play with in the spring.
As this is a newish rifle offering, and there isn't too much on the web about circumventing the Inconsistent bore issue. This thread here has more info in it than 10 other threads combined. Bore driver, sabots, and powerbelts seen to be able to maintain a good pressure fit for me.
After Muzzy season I will decide if the bore issue is going to work for me. I did go through a bit of a disappointment phaze, as the bullet I chose didn't work out. But with a new firearm you have to see what does and doesn't work. ---AMac