I'm still waiting to hear from the manufacturer whether it is sk60 or 75. From the stated line capacities you've indicated, this is probably sk60. I recall you mentioned something around testing and rating lines - average breaking strength vs ??? Are all lines rated by Average breaking strength or Minimum breaking strength? If so, why the discrepancy in rating?
O'tay. Let's see what I can type up here about ABS vs MBS vs WLL vs SWL vs Safety Factor.
ABS = Average Break Strength
MBS = Minimum Break Strength
WLL = Working Load Limit
SWL = Safe Working Load
ABS is pretty self explanatory. The ABS of a product is the average loading where a product is expected to break. There will be higher and lower breaks, but this is the average. This is typically determined by testing products to failure.
MBS is also pretty self explanatory. It is the minimum at which a product is expected to break - so the low break that was factored into the ABS. This is typically determined by testing products to failure. Standard deviations are used also to keep a very very high percentage of expected breaks above the MBS.
WLL is a fraction of the break strength of a procut, often 1/4 but you will also see anywhere from 1/2 to 1/6. So the break strength of a product would be anywhere from 2 to 6 times usually the WLL. This gives you a margin of safety that a shackle that is rated for 62,000 lbs ABS but has a WLL of 4.75 tons, or 9,500 lbs, should be able to operate safely at the WLL. This is important for rigging where injury or death can occur. This is especially important for lifting operations. Think of WLL as a "Design Load" or the maximum load the product is designed to encounter. You also need to think about the 'Yield Strength' of a product such as a shackle. A shackle will typically yield before it breaks - just to throw another bit of knowledge out there to stew on... Also, while shackles might have the same bow diameter and WLL, their safety factors, and therefore their break strengths, might be quite different. See more below.
SWL has been replace by WLL. "Safe" can be a bit of a misnomer.
Safety Factor is the number of times the actual break strength is larger than a WLL. So if a 3/4" Van Beest shackle has a WLL of 4.75 tons, or 9,500 lbs, and an actual break of 62,000 lbs, the Safety Factor is over 6.
So, why do some manufacturers use ABS and some use MBS? There are many reasons and I'll just touch on a few.
MBS is often used in the rigging (lifting) industry. Using MBS can help a bit with safety and liability when it comes to rigging, and much of the off-road recovery products you see come from rigging - BUT - rigging often deals with lifting and off-road we are pulling. These are very similar but also very different. For instance, with snatch straps and kinetic recovery ropes we want stretch. To get maximum stretch we have to near the breaking point of the device. If a kinetic recovery rope can stretch up to 30% but has an ABS of 30,000 lbs (to use a nice even number) then you only get 10% stretch at 10,000 lbs, 20% stretch at 20,000 lbs, and if you reeeeeealy need that full 30% stretch you are flirting with the rope going KAPOW!!!! and breaking.
Also think about the consequences of a broken product in lifting versus pulling. In lifting something is coming down when a product breaks which = a very likely chance someone could be hurt or killed. In pulling if a product breaks hopefully (hopefully) a vehicle is being safely operated and is not going to roll backwards. It can't drop because it is not being lifted. While in pulling there are definite significant chances for bad things to happen when a product breaks, it is different than lifting.
Lets chat a bit about synthetic winch line rating. Samson, who manufacturers Amsteel Blue, which is a Dyneema SK75 fiber, rates their lines with an ABS. But not all ABS's are equal. Samson's ABS is the spliced strength. Some line companies state the unspliced strength as ABS - so one company's ABS might not be the same as another company's ABS. All splices are not equal, and even the same two splices will act differently on their respective lines depending on technique, application, and skill of the splicer. I've taken apart numerous spliced lines for repairs, and sometimes just to add additional hardware, like a hook on to a bare thimble, to find out that the splice was improperly done. I have some pics of this that I need to post up...
Also look at products that are, let us say, manufactured at a poorer level of quality. At Southeast Overland we have repaired several lines made of inferior products, along with many lines made of quality materials. I have a piece of a "budget line" in the shop that has two very easy pulls on it and was in horrible shape for the amount of use it had seen. I also have part of a line in the shop that we repaired that was quality line and while it did break eventually it saw many more pulls and much more use than the budget line and appeared to be in about the same shape for the line. The quality hardware was still serviceable though, and the "budget line" hardware was trash.
With the popularity growing of synthetic winch lines, particularly Dyneema SK75, you will start to see more manufacturers producing the line for import into the US and other countries. Southeast Overland has been approached a couple of times by overseas companies to import their lines. I personally have dealt with importing for long enough to know what to look out for and I will not import synthetic winch lines from certain countries. While quality products are made from these locations a bunch of crap, for lack of a better word, is also made there.
Please note too that all Dyneema lines are not the same. SK90 is stronger than 75 which is stronger than 60. Most quality synthetic winch lines are made of Dyneema SK75. While 90 is stronger than 75 it is not widely used due to the increase in cost versus the increase in strength. SK75 hits a nice point of cost to strength. SK60 is used in many "budget" lines and is not as strong as SK75. Winch lines often have a woefully inadequate safety factor anyways, so reducing your line strength by using SK60 is headed in the wrong direction when dealing with safety.
If you do see a budget synthetic winch line with similar ratings to Amsteel Blue (3/8" = ABS of 19,600 lbs) check the diameter. One 'trick' that is being used is for less quality foreign manufactured lines to put a thicker line out there to match the ABS of a thinner, quality line. While you have the initial strength I have my doubts from my experience repairing these lines of the long-term strength. You also loose line capacity on the drum. A M8000 can hold 100' of 5/16" or 85' of 3/8". If you go up to 7/16" you lose additional capacity. You need 8 wraps minimum to keep your line attached to your winch, so take off that length and very soon you have a very short section of line that you can spool off your drum to attach safely to an anchor.
LOL - and timing is funny sometimes. I just received some load tested products back in the shop of a prototype product we are developing. This will be interesting to look at...
And now that my hands hurt from typing I'll hit 'reply' and let me know if there are any other questions.
and then everybody would think its a deal if it was cut from $600. 
