Quote Originally Posted by WhiteCottonFluff View Post
Bullets are probably too soft as they weigh 130gr from the mold. I tried the HB pencil test but I don't know how reliable this is.

With 4.2 gr S121 I get 960fps with no signs of over-pressure on the casings.

I'll just have to recover a bullet and see.
As an example of what can be done:

I cast my bullets from clip-on wheel weights and range scrap. The ingots come out around 12-14 BHN. After casting and again after baking on the PC, I water quench my bullets. This gives me a surface hardness of around 25 BHN on 9mm bullets. (Heavier bullets harden less.) Works fine in all my Glocks.

I once had a batch that only hardened to 17 BHN. Not sure why, would most likely have been the scrap lead alloy composition. (This was before I started powder coating.) They shot well in my Glocks, but would tumble from my Tanfoglio. (The Tanfo has conventional square-cut rifling.) I can only assume that the Tanfo's rifling is shallower, which allowed them to strip.

Too soft bullets can cause stripping, but there are other dangers too. They can also cause a build-up of fouling in the chamber and bore, that will lead to increases in pressure. This could be dangerous.

Powder selection is also important with cast bullets. Since the bullet hardness must exceed the peak chamber pressure, you have to either increase bullet hardness, or decrease chamber pressure, or do both. Generally, for a certain performance level, the slower powders will produce lower peak pressures. Faster powder will produce higher pressures. For this reason I now only use S221 with my 9mm cast bullet loads. It gives me that extra margin of safety that the faster powders can't.

Over-pressure signs on handgun brass are sometimes different from rifle brass. Most people will confuse excessive headspace signs as pressure signs. With moderate pressure loads most handgun brass should last for 40 to 50 reloading cycles. If the case heads bulge or the primer pockets become loose, the pressure is likely too high. To test your relods for safe pressure, select a batch of 10 once-fired (or new) cases and reload and shoot them as often as you can, keeping accurate records of the process. The round count at case failure for 50% of the batch should give you a good indication of the safety of your pressure levels. There is a difference between a load that does not rupture a case, and a load that will allow your case the maximum number of reload-cycles. The 3c that S221 costs more per round is easily offset by the increase in case life attainable.

To inspect the bearing surface of a fired bullet is difficult when recovered from sand. Try shooting it into water. A swimming pool works well. If the water is clear you can usually fish it out with a normal pool cleaning net. (Just don't frighten the neighbours!)