You are shooting commercially cast bullets. From my experiance, leading and poor accuracy is to be expected from most brands, because of three simple problems, listed in order of importance, or likelyhood.
They use wax for lube and it doesn't work.
The bullets are rarely a good design, but worse they are battered in mass production.
They probably are sized to noninal jacketed bullet diameter, which is too small for the majority of guns.
Gas checks cannot be added to plain base bullets.
The other problems are your guns vary dimensionally and in smoothness.
It is sometimes possible to make bullets shoot clean with the above problems by adjusting the loads for the individual guns to a pressure level where the bullet diameter just barely get bumped to fit the gun. - At this point the lube gets sealed into place, the bullet fills the rifling and stress on the bullet is minimum possible and still get the required bump up to fit the gun. If your bore is smooth, inadaquate lubrication will still shoot quite clean. Accuracy will probably be so so, by my standards, as I damand that any handgun/load I shoot be able to print a cylinder full into a ragged hole at 25 yards.
Almost all revolvers will get this type accuracy, and many will do it at 100 yards, but the only people I know of who can do it are those who cast their own bullets in LBT molds and use LBT lubricant, and most have to study my book 'Jacketed Performance with Cast Bullets', to understand all the requirements.
I sometimes feel like I'm sounding pushy about LBT products. Please understand that I could not get performance with cast which was acceptable in any way, even back when my standards weren't very high. So I put a lifetime of precision machine rebuilding experiance into finding the problems and developing the required lubrication, bullet designs and technology, or knowledge about the guns, so anyone, including new casters, could get results on the first go around. -- No other mold maker offers what LBT does, so I have to point everyone to LBT, or my advise is worthless.
To answer the rest of your questions: Get an LBT 4 cavity mold for each caliber handgun you shoot. It will produce 800 bullets per hore for me, and I haven't heard of anyone who can't get 600 per hour after a little experiance with it. My 4 cavity molds weigh less than an iron or steel 2 cavity, so they aren't tiring to work with.
The Magma sizer, which is the Star, is THE Rolls Royce of sizers. It is also the fastest by far.
Gas checks are available for all american calibers except .17. Hornady makes most of them, including Lyman and RCBS checks, and Bullet Swaging Supply makes what they don't.
When you put gas checks on with the Magma sizer, push the bullets nose first so the checks are clamped on squarely during sizing, or order bevel base bullets when you don't want to us gas checks.
If you have a bunch of commercial cast bullets which lead badly but that you want to use up, put a tiny smear of Tetra lube on each just before sizing. Just a drop on the index finger, smeared around the lube area will do. LBT Blue soft lubricant works very well used this way also, even though only a film is laid over the poor lubricant.
