These have the correct swell necks for the countersunk holes in the trunnions.
In my never ending quest to bring the best US made rivets to the builders I have been having numerous rivets made. I sell these to several manufacturers that swear by them and won't buy rivets from anywhere else.
You can't find more complete rivet sets with the different sizes of rivets with the correct style heads anywhere.
All rivets have been black oxide coate