I have recently started using adapters as connectors instead of using connectors as connectors. Huh?
When I make an order for stuff from either HG or HC I toss in some adapters. 10 or 20 don't run the shipping up to the next weight point and there are typically 5 for $7.
They are generally a little heftier that the connectors you find, check out the 801 bat to 510 atty connector on the HG site, massive chunk of chrome plated brass.
The one I've been using lately is the HG05100901. You can use it as a 510 bat to 901/808D-1 adapter or as a threaded in connector, or a pressed in connector for an 808D-1. I've found it needs just a little tuneup though.
In the SECOND photo attached, I've opened up the inner to outer connector clearance on the 510 male side. Beveled both edges and increased the protrusion of the center connector. If you are going to solder to the 510 side, dremel a small area to remove any chrome to give a clean brass area to solder to. With this adatper (510 to 901) Screw an old 901 atty on it as a heat sink when soldering.
On the 901/808D-1 male side (First photo), I've opened up one of the two breather holes and the inside a little because the insulator blocks off part of the air path.
And a photo of one mounted.
Rocket