anyone use

[Dave Waits]

Originally Posted by DrHenley

I LOVE Trail Boss in anything .45! I was using it a long time in 45 Colt before trying it in 45 ACP. I was having bad leading using HP-38 and cast bullets, and since I didn't have leading in the 45 Colt, I tried Trail Boss to see if that helped and it just about eliminated the leading.

Meters better than I expected. With an old Bonanza powder measure it's right on the money every time. With an RCBS measure it varies a little but still accurate.

Now I use it with both cast and jacketed, same load for both - 4.5 grains with a 230 grain pill. No leading with straight WW. With softer lead I get a little streaking near the chamber in one or two grooves.

Doc, how can the powder used have any effect on leading unless you were driving it near max charge? Velocity is what causes leading. I'm a big fan of HP-38/WW231 in the 45 and also Unique. No problems with lead buildup at all.
Average velocity for my HP-38 loads is 835fps.

[DrHenley]

Originally Posted by Dave Waits

Doc, how can the powder used have any effect on leading unless you were driving it near max charge? Velocity is what causes leading.

Dave, I am not an expert on such matters, so I would refer you to this page:

http://www.lasc.us/Fryxell_Book_Chapter_7_Leading.htm

There are quite a few different causes of leading, and if velocity were the sole cause I would not have had any leading because my velocity was pretty low! I assure you I DID have leading.

I bring this paragraph to your attention:

The other issue here is that the slow pistol powders reach their pressure peak when the bullet is an inch or two in front of the forcing cone, when the bullet is fully supported and contained by the barrel. Sealing and lubrication are fully functional in this environment. The fast pistol powders reach their peak pressure when the bullet is in the throat or traversing the cylinder gap. This is fine if the load involves modest pressures, but if a plain-based cast bullet is subjected to magnum pressures as it crosses the cylinder gap, then serious leading problems can arise. The take-home lesson here is to not use fast powders for magnum pressure levels in the first place! Just match the powder to the pressure curve.

Keep in mind these were light loads, right at the power floor for CDP class IDPA. My (non-expert) opinion is that peak pressure was not being realized with HP-38 quickly enough, causing some leading near the chamber in the barrel due to gas cutting of the bullet. Switching to a quicker powder caused the bullet to "bump up" quicker, resulting in full obturation sooner.