18" barrel old delrin bushings????

All right its time to get my 18″ barrel in. I have a older one with the delrin bushings and only 1 anchoring hole for each bushing. Should i drill out for the second and just leave it unthreaded?? I think this is my best bet, given what i understand.

Its my understanding you can’t tap Delrin with a conventional tap, true or false? A special tap is needed.

I’m cutting slits in the front bushing with a cutoff wheel 1/8″ deep or so. This is to vent the bushing and aid in noise reduction. Seems a better bet then removing the delrin and trying to get it back on if even possible. For now i’ll try the delrin and see how it performs, maybe i’ll get a set of bushings from Tony in the future. Thanks for the replies.