NHM-91 bipod fix?

The bipod on this rifle has thumbscrews to adjust the leg lenght. When is the middle of shooting the legs colaspe. I drilled two holes about 1/4 inch deep in the legs in the fully extended position. Hopeing this would keep the legs from colasping but the vibration of firing still loosens the screws and it colaspes. Any ideas on a fix for this?

[CALIFORNIAN]

Yes I had the same problem all you need to do
is go to the hardware store and get some
wooden dowl about the size to fit in the
bipod legs cut them to the desired length and
insert them in each of the bipod tubes then
put the support legs back in, you can even
wrap a little electrical tape on the wooden
dowls to keep them secure. That should keep
your bipod from slipping down.

Thanks but,I was looking for a fix that would keep the bipod adjustable.