Would like to know where you are using and what size threads? Rivnuts (another name for nutserts) are for fairly small threads with light load and low torque. Also what thickness and type of material are you rivnutting? They are not good for "bolts". There are better choices. Try to get a bolt out of a spinning blind rivnut sometime. They are used with aluminum or sheet metal when you can't possibly get behind to use a nut and washer or weld a nut plate in, etc. I have made many plates (nuts) with tapped holes in them and reached them into a blind area. 1/4-3/8 thk plate shaped not to spin in whatever area they are installed. But I don't know your application yet. Also maybe your definition of "nutserts" is not mine. A nutsert is riveted in, there are threaded inserts that are pressed in, welded in, peened over, wedged...
The spin out torque of a rivnut is LOWER than the standard torque of the fastener that fits it. Unless a hex one is used in a hex hole. Never found a place I had to use them yet on a truck. They were outlawed at the aerospace co. I worked for. Only good stories from guys who have used them on here so Go for it.

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