Excalibur Equinox Problem

[A/M/G]

I recently purchased a used equinox. I shot it several time before buying it, all good. Brought it home, waxed the string and shot it using the same bolts that came with it. The bolts are excalibur firebolts. The second shot it sounded like it dry fired, the bolt went about 10 yards, the target was 20 yards, and slid under the grass. Luckily I was able to find the bolt. Inspected the the blot and entire bow all looked good, extra emphasis on the limbs. Regrouped and shot again, first shot fine, second shot same thing, only this time could not find the bolt. Inspected the bow again all looks good. I was only using 2 bolts. I do not know if the same bolt did it both times. I weight the remaining bolt with the field tip it weighted 398.8gr well beyond the minimum 350gr. The only difference in the shots before I bought it and at home was:
1--The bolts had broadheads on them, I remove them and put field tips of equal weight.
2--waxed the string
Any ideas,as to what could be causing this, I am worried about blowing up the bow.

 

[bigtex]

Are you using half moon nocks or flat nocks?
Excalibur recommends flat nocks. If your using half moon's be sure the "groove" lines up with the string.
Sounds like the string is going over or under the shaft when you pull the trigger which could be caused by that little finger thingie that holds the shaft down being too loose.

 

[smokepolehall]

bigtex has it covered, seat arrow solid against string. Yer havin partial dryfires. CK yer string when arrow is loaded to see if'en its on the lower half of flat nock. Maybe yer string is to narrow dia. There be several good custom string makers fer Excals over on the Excal Forum

 

[A/M/G]

I figured it out. I was shooting flat nocks as excal recommends. Why they recommend that I don't know. Even the flat nocks have a groove in them for the string to ride in. I assume the groove was not line up correctly, not completely horizontal allowing the string to go over or under the bolt. I now am the owner of half moon nocks, if they are lined up there is no way that can happen again.

Another question, do yall unstring the bow when in storage? I have unstrung mine, thinking it will extend the life of the limbs.

 

[smokepolehall]

I have shot the flat nocks fer 15 yrs on my Excals never had that problem unless i got a string too small of dia. I leave mine strung yr around all of them. Glad to here you got yers shootin like you want it