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I have read several places that adding a light, or light and laser, to the Picatinny rail of a Glock can cause it to jam. I don't understand how this can be? I can see that adding a light or laser to the slide might add enough weight to affect the ejection system, but I'm at a loss for a light attached to the bottom rail of the receiver.

The only thing I can think of is that tightening the light on the Picatinny rail squeezes the rails together and binds something inside the slide... or the trigger assembly...

Am I close?
 

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I have read several places that adding a light, or light and laser, to the Picatinny rail of a Glock can cause it to jam. I don't understand how this can be? I can see that adding a light or laser to the slide might add enough weight to affect the ejection system, but I'm at a loss for a light attached to the bottom rail of the receiver.

The only thing I can think of is that tightening the light on the Picatinny rail squeezes the rails together and binds something inside the slide... or the trigger assembly...

Am I close?
I heard something close. I heard it was limited to the the Glock 22 and 23 with certain types of lights. I'll try to dig up where I read it to make sure. Now that I think of it, according to what I read, it was one of the reasons behind the Gen 4 Glock 22 coming out. The new recoil spring was suppose to address this. I don't know if it is true or not, Frank.
 

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it only affects some 40cal glocks.

this is off of streamlight's website:

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.

We have tried both stronger and weaker recoil springs, and compound-action recoil buffers, all without success. Sometimes new magazine springs, either new Glock® or Wolff, will cure the problem. In one case of a pistol which was totally reliable when new but progressed to malfunctioning on every magazine, even with no light installed, we found two solutions which restored reliability, but which might not be acceptable to some users. The first was using 10 round capacity Glock® magazines. The gun will not cycle reliably with 15 round mags with their steeply stacked columns but works flawlessly with 10 round mags. The second solution was a new magazine follower from Brownells®, their part number 069-000-006. When used in a 15 round magazine with a new spring, reliability was restored. However, the follower would not lock the slide open after the last round.

Ammunition is also a factor with any weapon. Some brands and weights may be totally reliable while others jam repeatedly. Make sure your gun is thoroughly tested with your duty ammo.

Brownells® is a registered trademark of Brownells®, Inc.
Glock® is a registered trademark of GLOCK Gesellschaft mbH.
 

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Go to the glock team web site and find the video of Gunny,when he shoots the glock (not sure what model )you will see the frame flex the most at the picatinny rail .Tighten a light on and the frame will not flex the way it should which is what might be causing the problem.
 

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The only one I had a problem with was with 40 cals. They did jam with one on them. I figure a look at the video Midnight was talking about should explain alot of what is happening
 

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Discussion Starter · #6 ·
Go to the glock team web site and find the video of Gunny,when he shoots the glock (not sure what model )you will see the frame flex the most at the picatinny rail .Tighten a light on and the frame will not flex the way it should which is what might be causing the problem.
Excellent answer... I have been trying to figure this our since the first time I read it... I just couldn't fathom how on earth a light under the front of the receiver could mechanically cause a misfire. I also didn't realize that the frame bent so much during shooting.

http://www.teamglock.com/videos.aspx

There's a link to the Team Glock videos... Click the video with a closeup of Gunney to see the video Midnight mentioned... I think sfguard posted this video earlier, too... It's a great super slow motion shot of a Glock firing.

Thanks...
 

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The old Glock .40 magazines had 10 coils in them. After the feeding issues were noted, Glock changed the design so that the mags now have 11 coil springs. I tend to stay away from the .40SW, but I haven't had any problems with in 9mm.

The frame actually flexes when firing. Adding the light adds rigidity to the frame.
 

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Go to the glock team web site and find the video of Gunny,when he shoots the glock (not sure what model )you will see the frame flex the most at the picatinny rail .Tighten a light on and the frame will not flex the way it should which is what might be causing the problem.
man thats some flexing. like a wave down the whole frame starting at the muzzle.
 
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