I went to the Boomershoot site yesterday. I spent the morning rearranging the Taj Mahal and managed to get all but about 100 pounds of the ammonium nitrate inside. On the drive home I realized I could get the remaining AN inside as well. I'll do that the next time I go back. I also cleaned up some spots that had rusted due to chemical spills and made changes such that spills will be much less likely to get on the metal in the future.
In the afternoon I started doing my experiments with reactive targets. I did six different experiments. I was able to determine a 1 3/8" thick target is no less sensitive than a 3" thick target. In each and every test the 1 3/8" thick target detonated with the same cartridge and at the same range (and in one case at a more distance range) than the 3" thick target. That is great news. This allows me to use larger shooting area targets without exceeding the neighbors tolerance for the house walls being shaken.
In experiments one and two I couldn't reliably detonate the targets even at 10 yards distant with .22LR Stinger ammo. With over ten hits at 10 yards I only got one detonation. Examination revealed burn without the boom. Black soot was around the entrance and sometimes the exit hole in the target. The .223 detonated the targets on the first shot. In experiment one I used the same chemical ratios as used for Boomershoot 2005 where we could usually detonate the targets with the same .22 rifle and ammo at 20 yards. At 20 yards the bullet velocity is about 1500 fps and at 10 yards it is about 1550. Something was different--I had introduced another variable and I knew what it was. It was how I mixed the chemicals. I made a change and in experiment three was able to detonate the targets on the first shot from 25 yards. At 25 yards the velocity is about 1475 fps.
If a little of that is good, then how about a lot of that? Experiment four--I moved the variable to it's limit. At 25 yards the targets detonated on the first shot. Experiment five used the same mixing proceedure but I shot from 40 yards away with an estimated bullet velocity of 1400 fps. One shot one boom. Experiment six, same mixing proceedure and I switched to a different ammo. American Eagle with a muzzle velocity of about 1200 fps. Four hits at 20 yards with an estimated velocity at the target of 1150 resulted in burn but no boom. At 12 yards I got one shot one boom and my thin plastic apron was perforated by small particles. I heard and felt particles bounce off my safety glasses. My legs, being without the body armor, stung from multiple hits and still have red marks 12 hours later. The pain didn't matter. The targets reliable detonated with an estimated target velocity of 1170 fps.
I made up another five targets and put them in storage for long range testing with the .223. If .223 bullets will detonate the targets at the same velocity as the .22LR bullets and storing the targets for a few days doesn't adversely affect the sensitivity then we may be able to detonate targets with a .223 at 700 yards.