Hey guys,
I just want to know everyones thoughts on weapons mounted lights and accuracy.( surefire, streamlight)
Thanks,

Nope, not at all.  If you run into one that does change with something attached to the rail, keep the light and get rid of the gun.

Actually in my experience followup shots are faster due to having a little more weight on the barrel end of the pistol...

As far as physical accuracy I cant imagine how a tac light would make any difference at all

Yes, light on your gun WILL DEFINATELY affect your accuracy.

It will IMPROVE your night-time shooting accuracy.

Being able to see your target is generally considered beneficial.

I shot a few hundred rounds through my Glock 19 gen 3 with a Surefire X300 mounted.  Never had an issue with accuracy.  It did screw up the light's bezel though.

I shoot my g19 faster and more accurately with its x300. And thats just durring the day. At night the difference is ... night and day

Do you mean it broke? Or just got dirty?

Here's what Streamlight says about the issue:

Issues Using Tactical Lights on Glock® Pistols

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.

Pretty much this.....

According to Werner Heisenberg- probably but you will never know for certain.

This.  The extra mass of the light out front reduces muzzle flip and helps the gun "settle" better on the target.  Plus being able to shoot/see better in the dark, but that has been mentioned.

less flip on recoil actually.

I've never had a problem with POI/POA after adding a light to my Glocks. As much as I love my Glocks, the one "issue" I have with them, albeit a minor one, is the flexible dust cover. I wish they were a little more rigid but it's not a deal breaker for me at all.

I also wondered if the problems with those certain G22s and G23s having reliability issues after lights were mounted were related to over tightening the clamp on the rail. I've never seen or read anything to back up that theory though. It's easy to squeeze the dust cover with just my fingers so I just snug up the light's clamp screw enough to keep it stable but never over tighten it. I have also checked it after shooting several rounds and it doesn't appear to come loose.

I rarely shoot with light on it though so I'm not sure about long term shooting with them. Just mainly to test function and where the beam centers in relations the the sights.

YMMV