John, I know that what you just wrote is true enough- strangely with cast bullets the opposite could be true as well. Goofy ain't they? In my current case there wasn't any visible leading (haven't cleaned it yet, but must not be much if at all)
John Boy, I hadda chuckle when I read yer post. You may be right about the warning of Vaseline in heat. (seems odd that 80 is "high" heat). The chuckle came from the suggestion to add mutton tallow. Nevada ranch ancestry here- no sheep allowed. 
Thanks fer all the help guys.

Yeah, John, but I was trying to say that the whole shooting and ammo craft has tricks of the game. Cast is no harder to learn than  the top tier of other disciplines. You must admit that shooting in the threes and loosing at a benchrest match is daunting. Those guys and their equipment is top notch. I tried, and soon found out that I wasn't gonna get too far in the listings. Fun though. And great atmosphere- very laid back bunch. 
High power wasn't for me either. Hurt my body, and those guys are uptight about everything. Everything.

Thank you Frank- I just shot off a note to Jerry.
In fact, let me give a thumbs up to the whole lot who've chimed in  on this. I feel like my favorite child just got sick and you all pitched in to help. 
The patient is recovering. No lead poisoning. Just lousy shooting for all I know. It happens.

Calledflyer,
I don't have any issues with heat and my lube, but may not have the heat your area has. My ammo is stored in my basement, so never gets over about 75 degrees, even in the hottest days of summer. It does sit out in the direct heat at the range, but not long enough to be an issue. I often don't shoot it all up at the range, but haven't seen any issues from heat.
As for Vaseline, I totally agree it can easily melt. But how much that affects the lube depends on how much Vaseline is in the formula. Since the formula I use has 10% Vaseline, I don't see it as a problem myself.

This reminds me of a funny, sad story. My old friend had a rifle with his cast bullets out by the river one hot day plinking at whatever struck his fancy. Hot day, like I said.
Soon his rifle started shooting poorly. He finally realized his problem was heat and unchambered his loaded round- to discover that it was free of lube- all melted away in the sunlit rifle's innards. He'd fired a number of wholly naked bullets and ruined his outing that day. One damn good reason for jacketed there, ain't it?

John Boy, that's kind of you to offer to the shooters here. 
My science is so weak, that I don't know what those properties you state are. I'm the same way with my medicines- just order 'em up doc, I don't need to know what they mean. 
Until now, it's been a case of so-far-so-good. Now that the lube is in question, I hope it doesn't follow over to my medicine too. 

A few years ago I decided to make my own lube. To give some background when I started, after trying most of what was out there, I used to use Havalina Schuetzen Lube (Smiley’s formula). I stopped using that when the Alox brand changed hands. The lube was different somehow I can’t explain it. Anyway I switched to SPG. I found that SPG was an excellent lube but it was a little fussy about heat. In southern summers it would start to run. A lot of guys used to carry their bullets in a cooler but that made my beer taste funny. What I wanted was something like a SPG but that would hold up to a little higher melt temp. After some research and experimentation I came up with my Dapper Dan formula. It will barely melt in a double boiler; I have found the best way to melt it is in the oven set at 220 degrees. Most of my 250s have been shot with it. 
Here it the formula, all ingredients except the Crisco are pharmaceutical grade.
2 lbs.      of beeswax
2 lbs.      castor wax
16 oz.      Lanolin oil
16 oz.       Castor oil
1 lb.              White Crisco
Melt in the order given. I'm still using my first batch.

40 Rod