ANTENNA

“Huge” variability in the base-to-end lengths of the Chinese-style antennas that fit the RFinder, Anytone, Baofeng, etc., radios. The thread length doesn't seem to be well standardized. Some fit, some are too short and don't connect, and some are too long and damage the radio's antenna connector. Once you have an adapter that works, you no longer have to think about it. Get a single adapter that demonstrably works, like a SMA-to-BNC a SMAJ-SMAJ adapter to use Japanese-style SMA-M connectors).

M6 antenna base:

• “You don't need to do it if your antenna is seated ok. I put my radio on a public service freq, then noticed reception got better if I bent the antenna around, but dropped off as it was. Part of that is likely me extending the antenna. There is a 1/16” over extension of rubber on my antenna. I trimmed that back and got a better connection.“ Source: David Dobbins.
  
• “I have horrible TX/RX with the M6 stock antenna. Put the stubby i use on the B1 onto the M6…almost perfect reception. Strangely enough if I put the M6's stock onto the B1 it works fine…I guess it seats better on the B1 than the M6.” Source: Mike Pasquale

SERVICE BULLETIN (from RFinder)
All SMA females are not alike from the perspective of the distance from the end of the connector (skirt just passed the threads) to the top of the dielectric. Do not over tighten because you will push the dielectric into the case. Only finger tighten if that… If you are having trouble because the pin doesn't not make it to the socket, file the end skirt down a bit.

Excellent fit on the B1-Plus, and provides a more stabilized connection between the antenna and body.
DIAMOND SMAJ-SMAJ Low Profile Black SMA-Female to SMA-Female Adapter