The 44 Carbine was designed for the 240 grain bullet. The User's Manual clearly stated this. The manual also warned against lead bullets. In the 1970s I owned two of these, and the didactic follows.
44 Carbine no. 1 was inaccurate. It would function normally with regular 220 or 240 grain bullet loads. Any 180 grain loads had to be HOT if the rifle was to work. I sold it, just too inaccurate.
44 Carbine no. 2 was as accurate as the Deerfield I now own. It would not function properly with any bullet weight, but approached normal best with the standard 240 grain load. Ruger repaired the feed mechanism. After the repair it worked fine if you scrubbed it clean and lubed it down every 50-100 shots or so. It never functioned correctly with anything but 240 grain loads. Sold it.
2000 rolls around and I buy a Deerfield (does this guy learn?) Well, Ruger got it right. The rifle is accurate enough; 3-4 MOA at 100 yards with its peep sights and a 2 MOA rifle with a scope. The load I use for hunting is the Speer 270 grain Gold Dot. The User's Manual says bullets under 215 grains weight and those over 255 may not allow proper magazine function. However, I have seen and others here have reported successfully using 300 grain bullets. Thus, the bullet cannelure placement or the crimp point along the bullet longitudinal seems to allow greater bullet weights to be used. This gun has had no functioning problems of any sort.
So, for your help. I would vote with Masterblaster on keeping the magazine/feed system VERY clean. I would add, insure the bolt and bolt carrier are free of any grit and lubricated. I used a graphite powder in this area to preclude sludge formation in the 70s, but this was before Breakfree. I would lube the entire mechanism with Breakfree if I owned a 44 Carbine today, as this lubricant works well in the far from clean AR15 series of weapons.