I’m looking to get get into casting my own bullets. I started to do this many years ago and life got it the way. I’d like to modify a Lee 45-70 , 405 grain hollow base. I’m thinking of grinding down the plug that makes it a hollow base. I’m guessing it would add 10-20 grains to the weight. Yes I could get a Lyman, but I need to stick to a budget. Any thoughts on this?

Well. You could. But why not just buy the standard 405gr or 500gr solid base designs from Lee? Is there some magic weight number in the middle you want to hit?

I like and my gun likes the shape and weight of the Lee bullet. I can’t find similar without spending money for a custom mold. I’m just wondering if it can be done safely. I don’t want to waste a mold if I don’t have to and I don’t want hot lead spilling all over.

I'm pretty sure the Lee 405gr solid is the same shape as the hollow base version, except the hollow base has longer driving bands. If you're happy with a 405gr bullet, I see no reason to start with the hollow base single cavity and modify it, when you could get the same thing or near to it with the factory solid two-cavity Lee mold.

Maybe I'm missing something in what you're trying to do, or maybe you're missing the fact that Lee already sells the same bullet mold design in solid base form?

I guess I should’ve mentioned I also need the .459 diameter. My apologies. The mild you refer to, is .457. I ordered one from Amazon and will try it. Amazon has a generous return policy

Meh, that part is easily corrected if needed, and anyway if you've owned many Lee molds you'll know that the as-cast diameter from them varies considerably from one mold to the next. The 405gr version I picked up recently drops closer to .460".

Easiest thing to do for larger diameter (if needed) is to use some small (like 1/8" square) pieces of aluminum exhaust tape on one mold block to space them apart. If that isn't enough, then lap the mold to the diameter you want. Or buy a .459" reamer (or have someone make you one) and ream out the lube grooves (can be done with just a drill press); if you powder coat then it's better without the grooves anyway.