Spend a few more bucks and get a good crimper and throw those shit connectors in the trash. Either get some of the ones posted with the heat shrink on them (provided they are adhesive lined) or go to the quality connector/terminal places online and order a selection there. This is an example of a quality terminal line. You want brazed or solid barrel with translucent insulation or no insulation and then apply adhesive lined heat shrink over that in dual wall.
The clear insulation lets you see that the insulation is butted to the barrel and that the wire isn't stripped too far.
https://www.delcity.net/store/Clear-Nylon!Insulated-Butt-Connectors/p_805411.h_805415
Get some crimpers like these. They cut wire, and do both insulated and non insulated terminals.
https://www.amazon.com/dp/B00004SBDI/?tag=wranglerorg-20
Thank you for the feedback, I found some connectors like @jeepins posted above on amazon that are adhesive lined. A quick scan of the site you linked looks like they only sell in pretty large quantities. I will have to double check on my desktop.
https://www.amazon.com/gp/product/B01GXQMP66/?tag=wranglerorg-20
I ordered the crimpers you recommended. As always thanks for sharing your experience.