Does anyone have any good solutions to this?

I do melt a hole first with a glue gun.
I'm using Mcmaster 1/2" grey foam.
I'm also using #6 Mcmaster washers.
I wash(ed) my hands when I made my darts.
I am using a low-temp glue gun (can be found below) and this glue:

I've just washed all of my washers. Threw them all in a large bowl, threw in some good soap, gave them all a good moving around and stuff, dried them thoroughly.
I sanded both sides of 5 of the washed washers with 220-grit sandpaper. I made 5 darts with the sanded and washed washers, 5 with just the washed washers, and 5 without washing.
5 darts isn't much of a testing group, but so far at 20ft away from concrete they all broke in either 1-2 shots. Most broke on the first. Did not notice a pattern in which group lasted longer. I will increase testing group size and post my results.
-tested with a 16" CPVC singled snapbow mk.5 from 20ft away from concrete. Snapbow was only hitting low 70's hoppered with #6 slugs
'makeitgo', on 07 Dec 2012 - 9:59 PM, said:
1. As well as washing your washers (like many have said). Wash your hands. Don't eat chips while you make your darts.
2. Rough sanding.
3. Glue isn't adhering to your washer very well. It could be that the glue has cooled down to much before you were able to get the felt washer combo on to the foam.
1. I washed my hands prior to making my darts. Also didn't eat chips while I was making them.
2. I found sanding the washers greatly increases the time it takes to make each dart. It also didn't seem to work for me, but I'm sure there was a difference between what you mean by "rough sanding" and how I sanded them. Despite how much I don't like the time and difficulty of it, I will test with more sanded washers.
3. I don't think this is it because there isn't much of a delay between the gluing and the adding of the tip. Only delay is of setting down the glue gun.
Quote
Though there is one defect (but not that big). I noticed that about 6 or 7 out of 400 started to rust.
Have not noticed any signs of rusting on mine. Probably because I dried my very thoroughly.
A picture of the level of sanding I do:

Edited by Naturalman7, 08 December 2012 - 07:18 PM.