Mike, you can get blunt tip needles (called drawing up needles)without the need to grind off the ends. I have had similar issues as I have been building on an open verandah with a roof (shared with the guinea pigs and the kids things) in lousy windy weather and it is suprising what the wind can move even when the resin is well into the glass. On the bigger bubbles I found making 2 holes allows the resin to go in one and the air to go out the other so need much less injection pressure.
cheers
David