Just got off the phone with Holosun support. The screws provided with the V2 pistol optics are as follows:
Long screws for picatinny mount: 6-32 x 3/8"
Short screws: 6-32 x 9/32"
He said the short screws are the correct length for the MOS plate, but some customers have had to file them down. Here's the kicker, McMaster Carr does not have a 6-32 x 9/32 black oxide Torx alloy steel fastener available. They only have 1/4" and 5/16" lengths, and 9/32" is in between.
*Edit
1/4" Screws are too short and I wound up using the Holosun provided screws. I did not need to file them as they stop just short of the bottom of the plate. The McMaster Carr 1/4" screws I got measured a bit shorter than 1/4", so I'm thinking the 5/16" length is the right screw to get, and be prepared to possibly have to file them. I can find no source for a 9/32" length torx fastener that is made of alloy steel. There appears to be nothing wrong with the Holosun provided screws, but I think it's worthwhile to source a box of quality fasteners if fielding these optics.