[fixthat]

I have a new PPQ M2 .22 and the end inside diameter of the threaded adapter is slightly larger than the barrel diameter and the thread "protector" hole is slightly smaller than the larger diameter.

The residue collects in there quickly and is impossible to remove.

I have tried a larger caliber brass brush with cleaning solvent and the shop tried an ultrasonic bath. Since it is a larger diameter it doesn't interfere, but I can't let it continue, and the bonehead i seem to be assigned to at the company doesn't know the difference between a PPQ and a P22

 

[WilmingtonNC]

Put a P22 suppressor adapter on it and you won't have those problems anymore.
You can find them on eBay for around $20.

 

[fixthat]

I have looked at the ebay list, is there a particular aftermarket supplier that does a better job or stick with brand name original?

 

[WilmingtonNC]

I just picked an inexpensive one, based off of which knurling I liked.
I have one on my P22 and one on My PPQ22