Andersen safety concern

[WDPatterson]

I looked at the pictures of the bolts. Those look like cut threads, not rolled threads. Rolled threads are stronger, because they are radiused, they don't have sharp edges and grooves.
That said, there is no bolt that is going to handle the force put on it from the side like that, because it's a bending force, not a shearing force. The rolled thread would stand up "better" to a bending force, but those look like cut threads which will form or grow a crack much more easily.. and, yes, grade 8 bolts are more brittle, less desirable than grade five bolts.
On the subject of both grades, is everyone here aware of all the grade two bolts which were sent from overseas labeled as grade five bolts, a few years back? More like 15 to 20 years back. Are you sure that problem has been fixed? Where were these bolts manufactured?
I've been using an Anderson hitch for about 6 years. I like it a lot. Never giving me any trouble. Can't say that I need chains, as I live in Texas. The bolts in the block that mounts on the Kingpin are far stronger and in a better situation than the bolts used for those chains.
Furthermore, as the dealer said, safety chains are intended to keep the trailer going in the right direction, not to keep it attached to the vehicle. They're only supposed to do their job momentarily, to straighten the trailer out, let the brakes on the trailer do the work, slow it down and stop it. You don't want that trailer to stay attached to your truck, if that hitch comes loose. You've seen already, too many wrecks, where the vehicle ends up rolls because it stayed attached to the trailer.
The situation of leaving the jack stands down, pulling forward with the truck, using only one chain, and perhaps being a little overzealous with the throttle, is what broke your bolt. That's just something you have to live with. It's not something you want to do twice. And, yes, both safety chains are necessary, if you're going to use one.
Both safety chains make sure that the trailer steers and stays behind your vehicle.
Anything else would be a pipe dream. They're only meant for a momentary protection to keep your trailer from going into the opposing Lane. That's all.

As a final statement, keep in mind that putting shocks in front of your wheels, leaving your jack stands down, and expecting your safety change to function as a means to keep it attached to your truck may not be in your best interest.

[sourdough]

For the "grade 5 is more desirable than grade 8" conversation because they are more brittle. Yes they are more brittle, but still stronger in every way as documented in many tests;

https://rtstools.com/are-grade-8-bol...s-10-9-metric/

[JRTJH]

As for the purpose of safety chains, this is from the Canadian government website referencing the purpose of the safety chains in towing trailers:

https://www.dmv.ca.gov/portal/handbo...has%20loosened.

When you look at the "logic behind the reason" the logic is that safety chains are there to restrain the trailer, to prevent it from being a greater hazard to OTHER PEOPLE on the highway. They serve other purposes, such as "guiding" your trailer to keep it from whipping out of the lane and getting sideways in the road, but the "main purpose" is to keep the trailer "chained to the tow vehicle" to prevent it from causing greater than necessary hazards to other traffic on the highway.

If the trailer comes "unhitched from the tow vehicle" it's not going to have the "torsional force of the hitch and WD bars to turn the tow vehicle over", rather the chains will twist as the trailer rolls onto its side (if the trailer does roll over), EVERY tow vehicle I've seen that has rolled with a trailer behind it, has had the hitch/WD bars (or both) still attached and it's the "torsional force" that causes the upset, not a loose chain rolling with the trailer.

[CedarCreekWoody]

Those are both interesting reads, and educational. Thanks to both of you for posting these!