I am about to send off my Remington UML to be converted to 45 caliber with LRMP ignition and muzzle brake. From what I gather, .45 cal high BC bullets sized to fit the bore are way more accurate and achieve much higher velocities than any .50 cal bullet. I am curious if anyone on here has gone down this road.

Forgive me for my ignorance on the terms you use, but I started using .45 cal bullets in my .50 cal a couple years ago. It was extremely tough getting the 50 bullet pushed down the barrel and when I inquired at several gun stores, they told me that I should be using a .45. It's still kind of a mystery to me for a variety of reasons, but they do work very well. I'd love to glean more of an explanation on all this.

That 50 cal with a 45 bullet in it should suffer from accuracy issues.

You are using a sabot with those 45’s right ?

I've got a Knight 45 cal that I spent a lot of time testing different projectiles on for accuracy. I finally settled on Crusher Rib sabots and .401 diameter pistol projectiles at 180 grains, though I suspect the 200 grain offerings would work well also. I can count on 1.5-2" groups at 100 yards if I am very careful with my powder measurements.

I've also always had great results from the Lee REAL bullets, I use them in 45, 50 and 54 with great accuracy, but I wanted a little higher velocity from my 45, so I went with the above mentioned load.

Yes sir, a sabot.

I’ve been shooting 45’s out of my 50 cal forever
The accuracy I get is comparable to my modern rifle
The last deer I killed was 150 yds out...broke both shoulders...which is what I intended to do
Finding the right bullet, sabot and powder can be a task but when you do you’ll have a killing machine
My combination is 300 grain Harvester Scorpion with a crush rib sabot and 110 grains of BH209

Some people are getting sub moa accuracy by using size to bore bullets in their MLs. They do not use a sabot but have to use a sizing die on their bullets to get the proper fit in their MLs bore.

Thanks Dead-eye. That gives me some confidence there. I've killed one deer, a buck in Illinois, with my muzzleloader. All the advice I was getting and the bullets I was seeing in stores, kept me wondering. I would consider myself still a novice in the ML
game, but I love the challenge and the pre-rifle week in Bami'. I believe one if my bucket-list goals of making the Alabama record book can can realistically happen with my muzzleloader. That .45 seems to shoot consistently, so I believe I'll make the permanent change. I'm rambling, but thank you again!