Thanks for everyones replies to my earlier post on the soft shackles.
DISCLAIMER: I am not a scientist, have no tools to measure force or load or stress. I weigh 220 pounds, and I used my weight to do the following test.
FYI: I WILL NOT be using these or any soft shackle to hang my hammock. I only hung my hammock on them to test their strength since I was curious if they could hold my weight.
TEST: On a swing set I wrapped 900 pound muletape around one side of the wooden beam and 1" webbing at the other end. I connected my 550 paracord soft shackle to the webbing and a climbing (metal) beaner to the other side of my soft shackle. I then made a double wrap of muletape around the climbing beaner and tied two half hitches...I stretched it all tight. I used two pillows to sit on (muletape isn't very comfortable) and held onto the chains of two swings. I sat down slowly...it held. I did a gentle bounce...it held, at this point there was lots of creaking of rope as everything settled.
I gently bounce for 5 minutes with no breaking so I turned it up. I bounced as hard as I could with my feet ready to catch me and using the swing set chains to pull myself up for each bounce. After 30 seconds of this I stopped, I had stopped breathing waiting for the break to happen.
Now I started the heavy bouncing again and after 1 minute of bouncing as hard as I could...SNAP! My feet caught me I started breathing again and I checked for what broke...not the 550 soft shackle?! I did think it would break first, what broke was the muletape right at the climbing beaner.
The 550 soft shackle had no signs of stress at all, it looked exactly the same as before the test, no burning or signs of fatigue where loop goes over the knot.
SO there you go...I am still not using them for my hammock since they are a pain to close while holding the hammock and trying to milk the loop shut.
550 soft shackles are pretty **** strong...not sure why or how long they would last, but they will hold way more than 50 pounds as someone noted.