Be advised that 38-55 rifles can vary quite a bit in groove diameter, sometimes making it tough to find loads that shoot well. The factory loads run .377" for bullets, barrels can run up to .381 diameter. I had one later comemortive 38-55 barrel that ran about .380-.381 diamter, and when a bullet of that diameter was loaded in a case, it wouldnt chamber, the chamber neck was too tight. Other report groove diameters ranging as small as .375". In the old black powder loads, the bullets were soft, and black powder is better at "bumping up" bullets than most smokeless loads, so they'd "fatten up" upon firing, allowing decent accuracy for what was an undersize bullet for the bore.
Some guns aren't hard to find decent loads that they like, some are. Many dont like tinkering enough to find those loads, others may simply stumble into them and be lucky, a few guys just get frustrated and give up.
When I had the barrel made for my project, I used a 375 H&H barrel, giving me a .375" groove diameter, they are easier to find bullets that fit than the wider bores.
"Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat." -Theodore Roosevelt-