So now we're blacklisting perfectly legitimate websites?

[screamingpotato]

It's none of your business, Avast, what we do legally.

"We've safely aborted connection on www.guntrustguru.com because it was infected with URL:Blacklist"

[DavidR]

Please break the active link to a suspect site for obvious reasons.

Avast doesn't block a site because of its content (on less that happened to be malicious) - before shooting the messenger (excuse the terrible pun), I don't work for Avast.

Some other hits here - https://www.virustotal.com/gui/url/2419dfb3d6bb4816c5d3077079db255db38584b258d05fd919c77e67fa8d8063?nocache=1
Security related issues reported here - https://en.internet.nl/site/guntrustguru.com/1901213/
Some outdated software related here - https://awesometechstack.com/analysis/website/guntrustguru.com/
Low Security Risk reported here, with some hardening improvements - https://sitecheck.sucuri.net/results/guntrustguru.com

These may or may not have contributed to the detection, but it would help site security.

Reporting a Possible False Positive File or Website - https://www.avast.com/false-positive-file-form.php.
You should get a response in a day or two.

[screamingpotato]

Hey I actually appreciate the pun, that was hilarious. 

The message wasn't that anything was detected, simply that it was on a blacklist.

I clicked all four of your links, last one flat out says it's good and not blacklisted on any of the 9 blacklists it checked. First one mentions 2 of 90 vendors flagged it and simply mentions categories from them are:
Forcepoint ThreatSeeker weapons
alphaMountain.ai Government/Legal, Phishing, Weapons
BitDefender weapons

2nd link I used that site to test other random sites and internet forums I hit daily (not firearms related) and about half of them had a worse score. They test silly things like if it's accessible with ipv6. I tested forum.avast.com with it and it scored better but had several of the same infractions.
3rd link had an "awesomeness analysis" (lol) of 80, and the only two suggestions provided both stated low impact. I can't test any other sites to see how they compare because it requires sign-up.

[DavidR]

That is why I didn't just post adverse links to try to give a balance.

The final link (5) is there to report a possible false positive