I like the .17 Fireball for night time predator hunting, we call up a lot of grey fox and this round is not too destructive or loud and is still enough for a coyote or bobcat. After much searching on the internet, I found a couple of examples where it had been done sucessfully but was unable to find complete info. Here is the scoop for anyone that want's to try it for themself. I started with a .17 caliber chrome moly barrel 1 in 9 twist. I had a RRA coyote 16" carbine as my plaform and wanted to keep the gun short and light so for the length of the barrel I chose 18" and the profile is 1" for the first 4" at the chamber then .75" for the remainder. I have an ACE Skeleton stock with whatever buffer and spring is standard (I need to check spring length and buffer weight). I decided to use a midlength gas system and from reading I found a couple references to .17 Rem working with a .078 gas port ... I figured that the .17 Rem should be a higher pressure than the Fireball and I would start here. I drilled a .060 hole and kept going up one number size drill until I reached .078. The gun functions perfectly and will lock the bolt back with Factory ammunition or my reloads, it is probably a little too much gas because I can see where brass hits the shell deflector on the upper and the brass is landing behind my right shoulder ... I am going to try a Wolf Extra Power Buffer spring soon. I am using a 20 round P-Mag that I converted to 5 round with a delrin spacer in the mag, just load the mag and tap it to seat the rounds to the back ... no problems so far. I learned quite a bit about AR's and machining and even made the device I used to etch the barrel. I had a gunsmith help me with the chambering ...I had never chambered a barrel before. With a 18" barrel the average velocity with factory ammo is 3600 fps. I also rust blued the barrel. Here are some pictures.
