Q: Are there Issues Using Tactical Lights on Glock® Pistols?
A: Some Glock® .40 caliber pistols, models 22 and 23, exhibit feeding malfunctions, either nose down or nose up (stovepipe), when used with tactical lights. The problems tend to occur with individual guns, with some pistols becoming totally unreliable while other identical, even close in serial number sequence, guns have no problems. Most models 22 and 23 are reliable.
A sensitive gun may malfunction with any tactical light - the TLRs, the older M models, and even Glock®’s own brand. There is evidence that the problem sometimes develops with use, and may progress until the pistol is unreliable even with no light attached.
On the basis of testing by Streamlight, we believe the problem is magazine related. It appears that the rounds are unable to rise fast enough for proper cycling. We have observed proper feeding for the first few rounds, consistent failures at mid-magazine capacity, and a return to proper feeding of the last few cartridges in the magazine.