bar feeding problem

While barfeeding 1/4 rod some times the bar pops out when the collet opens. The machine ran fine for 5 days then out of the blue crash. At first I thought it was the pusher hitting too hard, but it definitely is popping out when the collet opens. I have tried another collet but no good. It happens at the start of the bar the middle the end all over. SL-10 with haas bar feeder. Any suggestions.
Thanks art

I just recently had a similar problem running 1.625dia 52100 matl on my ST10.

When i called Haas CA about it, the guy i spoke to told me to change parameter 249 - chuck clamp delay from 1000 to 3000 [ms]. It keeps the pushrod behind the workpiece for an extra 2 seconds giving the collet time to close. Now, my understanding is this keeps the work from pulling back into the collet...but im not sure how it keeps it from jumping forward. All i can tell you is the issue hasnt happened for me again *knock on wood* but i cant tell you if its causation or dumb luck.

There is a parameter #376 or #356 or something like that called V max speed. this is in counts per second. I did the math 800,000 counts (the default setting) is about 400in/min. I dont think the bar feed ever has time to get up to that speed, but you could fiddle with the numbers. I worked out that 1500counts is ~1in/min. if you want to try slowing the speed down.

$.02