on still efficiency vs abv.....or where'd myalcohol go?

[tuckaloe]

Mentors,
I need some guidance.

I just ran my first UJSSM, which would be my 6th run through my 35 qt stove top pot still. 2"x 20 column, into a 20" Liebig. Interestingly, my abv seems low compared to the allbran and brown sugar rum washes that I've done recently.

So I got to wondering.....the UJSSM used a few lbs less sugar than my previous washes did. So there's less alcohol to be had. But.....shouldn't my still produce the same relative abv regardless of the % ETOH in the wash? Less volume of ETOH, but same abv?

For example, I ran a brown sugar wash and saw the first small jar abv 71%, 66%, 63%, 5 more jars at 62% and then a gradual drop into the 50% range before I went to larger tails jars.

But this run of UJSSM netted me a fores jar of 66%, next was 55%, 52%, 52%, 50%,48%, 46%, 45%, 42%(tastes bad, tails obvious).

Granted it's a new recipe and due to the struggles of siphoning off a cracked corn bed, I didn't get a full charge in the still. But...here's that "but" again...shouldn't my relatively inefficient pot still be producting similar %, regardless of the recipe and it's ETOH volume? I get the fact that a lower abv wash or lower volume will reduce the amount of hearts(and every other cut), but why are the abv so different after distilling? Any thoughts on this? I'm perplexed and wondering what I'm missing or not understanding sufficiently......

The 600ml or so of hearts that I got are pretty tasty. Enjoying them with a splash of local maple syrup, tis the season....