AR Barrel Question-notch?

[sschudalla]

Why do many AR barrels have a notch machined into them approximately 3/4" down the length of them? It is about .5" in width. Isnt barrel rigidity a key contributor to accuracy and if so, material removal does lower strength in that wall thickness? I cant imagine this is some type of weight savings. Nothings fits up at that point? It is on my DPMS AP4 LR308 and I have seen it on many other "standard" AR barrels? Was looking over my rifle (yes, admiring it) and thought I would ask. Just curious...

 

[atblis]

To mount a grenade launcher originally, but is more or less cosmetic (to mimic the M4).

 

[Robert]

If you are talking about the notch that is forward of the front sight base/ gas block and to the rear of the muzzle it is the notch for a M203 Grande launcher.

 

[sschudalla]

Learn something new every day. Mcrae, like your tagline.