I have use regular lighters and the extension lighters. Anyone with any tip to melt the end of those fiber optic tube.

What about butane torch? Too much heat?

I use either a regular lighter or a BBQ lighter.

The trick is not to put it in the flame. Slowly move the flame closer to it just starts to melt. Too close and hot seems to make them brittle and they don’t last. I went through several in a weekend before someone showed me the trick.

I’ve got several thousand rounds on my current one. It needs changed because it’s dirty.

I've used a butane lighter before and it seems to melt it unevenly. I probably had the flame a bit too close, but the problem is the flame jet was pretty strong.

I've used a regular Bic lighter in the past and never had an issue.

Use a box cutter of knife. Heat the blade til hot. Then gently press the tip of the fiber optic rod against the blade.

I trimmed mine with straight edge toenail clippers and then just used a regular lighter, getting closer to the end as stated above though not contacting the fiber optic. It will mushroom a bit and then that will help seal it so it cannot back out. Worked perfectly for my Kimber 1911. YouTube helped when I had questions on technique.

Here's the method I followed.