I'd just ask.
One thing to watch for on LE ranges that you likely won't encounter on a regular range could possibly be the following:
- Tracers
- Frangible Ammunition
- Non-toxic Ammunition
I'd ask if any of some of the above have been used before on this range, and even if not, carefully pick through what you pick up there- or on any range.
Putting an non-ignited tracer into a pot of molten lead might get you win a prize for the high jump.
The other thing to think about is the non-tox stuff, which is sometimes made of bismuth, which can also contaminate a melt I've heard- have never run into that myself, as I've never used range lead from anywhere but an indoor range.
Just my two-cents.