I am reloading a cast 240 grain non-gas check 44 mag bullet over 14.5 grains of Blue Dot powder. The load averages 1260 ft/sec from my S&W revolver. After 18 rounds the barrel shows quite a bit of leading. According to the Lee reloading book, the max load is 16 grains of Blue Dot. I am thinking of using a polyster quilting material between the powder and bullet.

Will the filler help stop the leading and will the filler cause an increase in pressure?

Leading usually occurs around 1000 fps unless hardened bullets are used. It's unlikely that filler will do anything to prevent that. Either get a harder and/or gas checked bullet or cut back the velocity.

I am reloading a cast 240 grain non-gas check 44 mag bullet over 14.5 grains of Blue Dot powder. The load averages 1260 ft/sec from my S&W revolver. After 18 rounds the barrel shows quite a bit of leading. According to the Lee reloading book, the max load is 16 grains of Blue Dot. I am thinking of using a polyster quilting material between the powder and bullet.

Will the filler help stop the leading and will the filler cause an increase in pressure?

Question:

Does the leading first show up at the cylinder face/forcing cone, which usually looks kind of "lumpy"? ...or does it just kind of show up throughout the barrel as streaking-type leading?

The leading first shows up close to the cyclinder end of the barrel and then moves toward the muzzle as more shots are fired.

Sounds like normal lead buildup caused by shooting too soft a bullet, or too high velocity.

As others have suggested, a harder cast bullet or use of gas checks should help. Maybe both. Marshall has recommendations as far as proper lube for cast bullets goes.

Sounds like normal lead buildup caused by shooting too soft a bullet, or too high velocity.

As others have suggested, a harder cast bullet or use of gas checks should help. Maybe both. Marshall has recommendations as far as proper lube for cast bullets goes.

If it were just velocity related (bullet alloy or bullet lube), then the leading would show up where the velcity was highest.; probably a combination like kdub mentioned more than one cause.

Bullet of a larger diameter might help things a bit, but making bullets that you already have larger isn't a trick we can peform.

Ifg the bullets are already of a hard alloy, then I'd suspect that the diameter is a tad small for that particular gun....rock hard undersised bullets will usually leave a kind of lead "plaster" in the breech end of the barrel from lead being eroded by gas jetting past the sides.

One thiong for sure, lead has a tendency to grab on to itself, so when a little bit starts, it tends to collect more of itself pretty quickly.