Anyone who was referring to " a blob of jam " as in blood.
You are absolutely right that clotted blood looks like jelly. As it coagulates it looks bubbled. Some guy had a stroke, cracked his head on the floor and bled a lot. I had to clean it up after they finally took him away. It was nasty, it was coagulating and did have bubbles and looked like jelly. The floor tiles were white, it really stood out. But we are talking about a tiny tiny amount of blood that the family could see.
You can't see deep inside a moderator or gun barrel so they could not see much. I have a bore light that I use to look inside the barrels of my weapons to clean them. They probably had their own bore lights but none of them claimed they got one out. They saw the little bit of blood that dried right in the opening they could not see deeper inside because it was too dark. The inside of the opening had a thread where the blood could collect so that it would be in line with the hole. If not for that thread the blood would have sat against the wall and thus would not have been visible. I doubt that tiny drop of blood would be a ball. It would be hard to describe it's shape given the small size.
There are countless things one can use to try to describe a little bit of blood that you see there stuck in the opening. Something you choose or that I choose could be totally different from what someone else chooses the same way one person can describe the color of something much different than another will. Descriptions by people are often not helpful. I can describe clothing people wear and their hair color and skin color but if a sketch artist asks me to describe their mouth and nose etc I an worthless. Some people are like that with more than just faces.
The only thing the family can tell us of value is that there was a little blood in the opening. Their descriptions were not particularly useful. It was such a small amount the lab could only test whether it was human they didn't have enough left to successfully type test it. That is much more useful at telling us how small it truly was. Dr Lincoln swabbed the threads and he found enough blood still stuck in the threads to type test it- it was Sheila's blood type. If he could successfully type test the blood still stuck in the threads then the lab should have been able to have enough blood to split in half to test half it is is human and the other half for type testing unless the amount removed was quite small. So the amount in the threads can't have been as much as what the family descriptions evoke.