Well to answer a few of your questions about reloading 22lr. I am using a primer now that is basically roll cap powder with about 10% fine aluminum powder mixed in. The aluminum seem to give it a considerably hotter (more fire and sparks) ignition. I have done all of my experimenting in an old Remington 514 single shot rifle so far. My failure rate is contingent upon what sort of experiment I am doing at the time. I have failures isolated to one problem now. When I do the seating of the bullet or the "final sizing" of the round, sometimes the pressure causes the head to get slightly concave which "pops" the primer loose inside, causing a non-fire. Other than that, I have the powder type and charge, bullet weight, diameter, hardness and lube figured out. I am in the process of changing my experimental dies from mild steel and Grade 5 hardened bolts to high speed steel and grade 8 hardened bolts. The softer ones expand after a couple hundred rounds or less. I found through some research online that Vihtavuori 3n37 was originally developed for rimfire and indeed there is at least one manufacturer in Europe that uses it in 22LR. I couldn't find that so I searched for a similar powder and found that HS-6 was recommended as a replacement. So I use that. It works very well for 22LR. It is the only powder I have ever seen (I only have been reloading for about 5 months now) but it "looks" almost exactly like what is in factory 22LR. I read that 22 magnums use slower burning powder so I don't know if I should continue to experiment with HS-6 for them or start with a completely different powder. The only gun I have currently that shoots 22 Mag is my new little Heritage Rough Rider revolver. (It has a 22LR cylinder and a 22 Mag cylinder.) I have not used it for ANY of my reloads because I don't want to take a chance with it. I guess I am going to have to pick up an old 22 magnum rifle to experiment with. That will probably be the hardest challenge yet. To answer a couple of other questions, the dent from the firing pin can be opened up with a hydraulic sizing technique that I came up with. But it isn't really necessary. Most of the dents are just open enough to be able to get a bit of primer behind them and enabling them to work. I have had struggles with consistency. The big thing is crimping. The crimping method I use is a squeeze method. I cut a die out of a cheap pair of lineman's pliers that has a very fine line for crimping. It is dependent on the length of the case for accuracy of where the crimp will be. The cases are not all exactly the same length. So I guess I am going to have to make a case trimmer to get that corrected.
Now that it is heading towards spring and 22lr ammo is pretty easy to get at a fairly reasonable price, this whole process is getting to be tiring. I thought I would switch to reloading 22 magnums for a while.
Oh, it costs about 3 cents per round to reload at the prices that I have paid for powder, primer, lead and empty cases.
