I use a Hawkeye for fine inspection, but have used a couple of the endoscope types for quick inspections at the range or in the field.
The endoscopes are getting better, but the best ones have stronger illumination and 90* adapters for side views. I had an early one, the light was so weak I had to run in white patches from muzzle end to reflect light. The last one had good light, but no 90* reflector. My son got a new one off Amazon and he loves it.
Be sure you find one with a small enough head to pass into your barrels and has the 90* adapter. Sorry I don't have any current model names for you, but Amazon is where my son found his.