I have had the same experience as Brian. They can be a little finicky about what you feed them. I did order a set of Wolf springs for mine. Not sure it really made a lot of difference, but they are shooters.
Whatever you do, don't use a copper brush for cleaning. Use cotton and Hoppe's only. They have very precise and delicate barrels. No borescopes either for sighting in. These things are really one handed rifles.
The M41 that I have cycles best with MiniMags (HV) and most standard vel target ammo will have cycling issues especially with the first round or two out of the magazine. This isn't a factor of having a dirty gun or no lubrication either. I suppose I could go with a different recoil spring if I really wanted to shoot the standard vel ammo all the time.
The use of target grade ammo would be important if you were trying to get the full accuracy potential out of the gun but the CCI Minimags shoot alot better than I am capable of and like Chango said they do shoot like rifles even with the HV stuff.
You'll hear a lot of BS on this issue. Just wait. "These are high-grade guns, and a steady diet of high velocity will damage them." If you hang around the "niche-specific" forums long enough, you'll inevitably hear some old fart claim, "The gun was designed for ____ brand of ammo, that's what Smith and Wesson told me." (With no proof, of course). Heck, someone may even trot that out here, if we wait a bit...
But no...It's a high-quality, all-steel, American-made .22lr, it's "designed" for SAAMI-spec ammo just like the others, and high velocity ammo will not damage it. That being said, ammo quality varies, and not all types will function equally. In the "old days," bargain ammo seemed to work ok, but I think certain brands have really slipped in their quality during the modern age. You might find you need to stay away from brands that have a "gummy" or waxy lube around the bullets, like Super-X used to have. Look for brands that have a clean, smooth appearance on the bullet with nothing "sticky."
Before I figured out what to feed it, I could usually count on 2 or 3 alibis per match. I have learned that I have no reliability problems whatsoever, and my .22 will now feed just as reliably as my .45, if I feed mine CCI Standard Velocity for practice, and Eley for matches.
(If you're one of the pigeon-feeders who sits outside your local Gander Mountain Friday mornings waiting to buy up all the "cheap" high-velocity ammo, you might not get flawless feeding...but you're probably not shooting matches, either, so you won't mind).
I experimented a great deal with .22 ammo and my mod.41. It likes Win. T22's the best. Eley tenex was the next best. I crono'ed about 15 different brands and found out that .22 long and .22 long rifle are exactly the same speed coming out of the barrel. You can only gain the higher velocity by using a longer barrel, i.e. a rifle barrel.
I do not think there is any ammo that will hurt your 41. some will feed, some won't. some will group good, some won't.
Mine's been around a while SN# 94XX. 90% of what it's eaten has been HV. Did have to replace an extractor last year. I agree with buzz-gun about the quality of some of the cheaper name brand ammo now days. From shooting ones other than mine and talking to guys that own and shoot them regularly;it seems as though each gun has its own personality. Some shoot one brand and velocity better than another one,etc. They sure are one sweet gun. Quite a few guns I've owned have gone down the road;this one will be with me when I go down the road.