Honestly, that was my thought - but EJ said they were the proper size (several were new). For the life of me, I don't know how they could manage to jam because of the port - but the fact remains that they have, and that was enough to convince me that I didn't want to use 'em any more on anything with a gas port. Beyond there, as noted by several - they don't REALLY do THAT good a job. I found 'em to help speed up the process when used in conjunction with my cleaning routine, but a good bore brush is more compact than the various sizes you need to tote, so to me it wasn't any big loss to get rid of 'em.