I shoot a .54 Lyman GP hunter and after hearing good things about the NE bullets I decided to try them. I called him and was advised he made two sizes in .54: .541 and the slightly larger .542. I ordered a box of .541 and he threw in a few .542 to try. I went to load the .542 and when I released the bullet over the barrel it fell to the bottom. When I tipped the barrel downward and gave it a shake the bullet fell out. The same thing happened on my TC Renegade with an Orion barrel. The bullet seemed to fit as it should on my Investarms rifle. I called the owner and he explained that the bullet ridges are the same size, meaning there is no larger ridge that engages the lands. He mentioned that some people use tape to build up the bullet diameter. These are a fine well made bullet and my only reason for posting is to give a heads-up and suggest that when considering these bullets maybe order a sample of both sizes to see if they will work for you. Not criticizing the product or company in any way, wished they worked for me.