I have used them before and while stump shooting have hit stumps that were not as rotten as I thought they were and had the nock of the arrow fly off and the tube sticking out of the shaft. If that arrow hit a deers rib, would it do the same thing? And, wouldn't that cause some serious penetration problems. It seems that an arrow staying intact would penetrate better than an arrow flying apart like that. Would an intact lighter arrow be better?

Back when I used tubes I never had one fail on an animal...but I did have the nock blow out when the shaft stopped abruptly from hitting something hard like a big rock or stump. I don't think the shaft would stop so abrubtly with a broadhead on an animal.

Crimping the tube in several places while rotating it has stopped the "flying nock" for me.  The tube takes some effort to get into the arrow afterwards, but it is worth it.  My arrows seem magnetically drawn to the support beam behind the straw bale.

Thanks for the tip Jeff.  I lightly glued mine and I still had a couple nocks blow off hitting frozen target etc.    

How exactly did you crimp ?  Bending sharply ? Tool ?

Thanks

The way it was explained to me was, that the tube has to fit perfectly from the back of the insert to the knock inside the shaft to prevent inertia from blowing the knock out, it takes careful measurement but it does help, I've heard useing supper glue works too.

I apologize for the delay, went out shooting with my brother.  I use needlenose pliers and crimp them hard.  There's a nice video on 3Rivers on their weight tubes page.

http://www.3riversarchery.com/Product.asp?c=58&s=187&p=0&i=6731%2D2X

Here is the link to the video on installing them.  Hope it helps.

I just superglue the nock in.  No more wondering...

Cool.  I think I'll do both.  But only glue after tuning the nock orientation.

Good info. everyone! Thank you!