I was looking for a part number like 01604-00414. I don't know how to decipher those numbers for details, but I suspect that LP4-3 only specifies the size... And I'm not able to dimple, so I'm looking for plain heads.
Go to the Aircraft Spruce Website and search for AVEX Rivets. They will be listed as AVEX non-structural rivets. Disregard the non-structural part of the description, I'm still baffled why they do that. They have a chart that lists all the grip lengths etc. PM if you have any questions, as I'm quite familiar with them.
The rivets supplied by Van's for my RV-12 are NOT Avrex .... they are manufactured by Gesipa and are part number GSDM41-43APG. In the RV-12 plans, Van's refers to these rivets as LP4-3 rivets. The rivets are from Gesipa's series of rivets called Polygrip Multigrip blind rivets. It is an aluminum rivet with a steel mandrel that has a grip range from .039" -.197". Specifications for minimum strength are a shear of 162 lbs and tensile of 236 lbs.
The photo below shows the box of rivets Van's supplied with the RV-12 kit on the left. Also in the photo on the right are the flush rivets I purchased from Gesipa that were used to build my RV-12 (yes, I built E-AB) ... the flush rivets have the same tensile and shear strength as the low dome rivets from Van's and the part number is the same except the D is changed to a C for the countersunk version (the D is for low dome).
Forgot to mention Gesipa has a minimum order of 10,000 and would not sell retail. I asked for and was given the name of a distributor in my area which subsequently ordered the rivets I needed for the external surfaces on the RV-12 project. (The RV-12 needed over 9,000 rivets because I went into the 10th box of 1,000).
Apparently roughly three years ago or so Gesipa changed the part numbers for their product line of PolyGrip multigrip rivets and also changed the grip ranges.
As for the distributor I used ... don't remember the name because it was a one time purchase. To find a distributor, I just called Gesipa directly and asked for names of distributors in my area ... found one about 17 miles away and did a will call pickup after my rivets arrived, so saved a little on shipping. I would suggest you call Gesipa directly and find a distributor local to you.
If you still want the name of the distributor I used, PM me and I will see if I can find the receipt.