Breaking nocks

[XB I GO]

I moved the nocks so the line showed on all of them in the picture.

[bigbowman]

Looks like one shot caught part of an orange blazer too. I agree with Boo! Looks like damage from shooting tight groups?

[taz3]

It looks like the nock is being damaged from the rail, the shafts are much harder the the nock, so they won't mark as easily. If you look at the rail where it meets the trigger, you may find a burr. I would be inclined to remove the string and manually slide a bolt along the rail to see if the rail is causing your issue.

[Kegbelly]

I get slight rub marks on the sides my knocks where they contact the rail, and I also use the Black Eagle knocks I bought when I bought my shafts. I always thought it was normal wear and marking from the knock contacting the rail. But I never got any chipping or damage though, makes me think the arrow isn't seated all the way against the string or you have a rough spot somewhere on the rail.

[Deaf jeff]

just a thought......
are the factory stickers on the arrows, are they showing any wear? might be possible that the residue on the rail from the stickers is transferring to the nocks do you clean the rail at all

[nchunterkw]

I'm pretty sure the mark is from the rail. The chipping seems odd though. Is there a rough spot on the rail or a seam between the rail and riser that is not perfectly aligned? Run an arrow down the rail by hand and see if you can feel it catch on something.

[janesy]

Its carbon tranfering from the arrow to the nock. Some of my arrows that have been shots lots of times have developed a wear line which would transfer to the nock if the nock material was able to show it.

Check the rail for a rough spot, thats happening WAY too fast

But also those do look pretty beat up. Might want to make sures its really seated as earlier suggested.

[SEW]

Hmmm...are you placing the orange fletching in the down position? I see the same mark in the same position or orientation.

If it’s from the rail, the cock vane must be on the side.

[BrotherRon]

My nocks have the same black lines on them and it is from a rough rail... however mine are not chewed up as badly as yours!
I can also see light scrape marks on my arrow shafts as well, but not bad.
If you look closely at your rail I believe you will be able to find some yellow from your nocks and be able to pinpoint exactly where it is happening.

[Tichound]

Did you ever get this sorted out?

[XB I GO]

No. We cant find a rough spot on the rail. The Axiom is a plastic rail anyway. I turned the nocks that we still used and they have a faint line starting on them just like the others. I haven't shot enough lately to see if the nocks chipped more. After school is over I'll be shooting a lot more.

[BrotherRon]

Check where the rail meets the riser.

[taz3]

I wonder if you put a mark all the way around the knock with a grease pencil to see if it may transfer to the crossbow where it is making the contact. I would suggest putting it on fairly liberal so you can identify where it might be. If it is making too large of a mark you can always decrease the amount and it shouldn't have much, if any affect on the performance.

Good luck and keep us posted, I know I'm curious about the results of the cause!