How often should a bore brush be inserted into the chamber end of the barrel when cleaning?

In the context of maintaining the M9 service pistol, using a bore brush is crucial for ensuring the internal cleanliness of the barrel, which directly impacts accuracy and performance. The recommended practice typically involves inserting the bore brush multiple times to effectively scrub away fouling, carbon build-up, and other residues that accumulate from firing.

Inserting the bore brush seven times allows for sufficient contact with the barrel's interior. This level of repetition ensures that the bristles thoroughly clean the bore, reaching all areas and providing an effective cleaning without overdoing it. Overly frequent application, such as 10-12 times, could potentially lead to excessive wear on the brush and possibly damage the rifling if repeated force is applied. Therefore, the correct number of times the bore brush should be inserted is balanced to promote effective cleaning while preserving the integrity of the barrel over time. This understanding of cleaning techniques is vital for maintaining firearm reliability and longevity.