The adequate performance of, both, lead and plated bullets in your firearm depends on several variables:
(1) Proper bullet sizing - Which should be no more than .003 oversized and tested in your particular barrel for proper performance.
(2) Proper bullet lubrication and surface coating (Alox treatment).
(3) Proper hardness (antimony & tin content) of the lead used to make the bullets; as well as,
(4) The original source of the lead, its original use, and the method of its initial manufacture.
Many commercial lead bullet manufacturers cut and swag their lead bullets from large rolls of very soft (less than 10 BHN) lead wire While this type of bullet CAN be used - with care - in mandrel-formed (polygonal rifled) barrels, it is definitely not prudent! Mandrel-formed barrels require the use of hard cast lead bullets with a fairly high BHN (Brinell Hardness Number) rating of between 15 and 20 BHN.
Whenever you shoot lead bullets its always a good idea to keep an eye on the bore and to occasionally wet-brush it out. When youre just beginning with lead bullets, it's a good idea to stop and check your bore every 50-100 rounds. It is, also, imperative that BEFORE shooting lead in any barrel, you should make certain that all copper jacket fouling has been removed.
(Copper jacket removal from the bore is a job for a copper cleaning solution like; 'Sweet's 7.62' but, READ THE INSTRUCTIONS and never leave this - or any other - ammonia-based solvent inside the barrel for more than 5 to 8 minutes at a time!)
Most lead bullets are, by design, .001" oversized. This is, however, not always a perfect match for the barrel you're using. Don't start with a huge quantity of new lead bullets; you might find that .002" over is a better fit that will result in much better accuracy and much less leading in your particular pistol. Experiment a little, first, and see what works best in your Glock.
Proper fit between the lead bullet and the barrel is equally as important as proper bullet hardness. Try to keep your lead loads running at less than 1,000 fps. Remember that accuracy is largely more important than ripping velocity. In any event the faster you make your bullets go, the harder (higher BHN) those bullets are going to have to be.
Lets talk, a little, about sources of lead: Sometimes lead can be expensive to buy or difficult to find. Wheel weights which can often be found at garages and tire stores are the best commercial source for hard lead. Typically, wheel weights are made up of about 3% antimony and 0.5% tin.
However, the tin doesnt increase the bullets hardness; (BHN) instead, it helps the lead to flow better into the mold. Its the type and amount of antimony that controls hardness. A BHN of 11 or 12 will work in a 45 acp caliber pistol; however, I strongly suspect youll be better off using lead that has a BHN of between 15 and 18.
Its always a good idea to take a really soft piece of lead and slug out your barrel before beginning to shoot a lot of lead bullets. A thousandth over should be fine for most pistols; however, in no case, would I go more than two thousandths over inside a mandrel-formed barrel; and, if I went to .002 in any barrel, then, Id keep the BHN at around 15 or less.
Using lead bullets is, kind of, like a balancing act: Youve got to experiment around with this and that in order to discover what works best in your particular pistol and with your particular load.
As in all reloading, start with small samples of the round you plan on using and check for things like: feeding reliability, overpressure, and excessive barrel leading. Begin with reduced powder charges and work your loads up by tenths of a grain until you achieve the: reliability, accuracy, point-of-impact, (grouping) and recoil characteristics best suited to the kind of shooting you do.
A word about Glocks: It's not that you can't shoot lead in a Glock. Heckler & Koch, also, uses mandrel-formed polygonal rifled barrels; and, to the best of my knowledge, H&K has no objection to the use of lead bullets.
Another word about what reloading equipment you decide to buy: Sure, I read your instructions; and, yes, price is always important. It has, however, been my experience that the brand of reloading equipment you start out with is the brand you will stay with for many, many years to come. Personally Im a, green or blue reloader. My single stage (rifle and small batch) press is an old extremely overbuilt RCBS Rockchucker. My progressive (pistol) press is a Dillon.
You should be aware that you are going to buy the manufacturers technical support department when you buy the press. Nobody has better technical service than RCBS; but, Dillon runs a close second and does a very good job, too. The choice remains yours; so, good luck!
One last thing: If you dont want to fool around with casting lead inside your home, (Most reloaders Ive known cast lead in either their: kitchen, basement, or garage - True!) then you might want to look into the use of bulk-purchased copper-plated bullets from a company like Berry Manufacturing or Rainier.