Robert,
I recall Brownells had a solder with a lower than 60/40 temp by maybe 100F. I don't recall the name. Perhaps that was what you recall?

I've recently used HiForce 44 for assembling the spacers between a set of barrels. The idea being that I could regulate the barrels without ribs then 60/40 solder the ribs without worry of detaching the spacers.