cafe owner has AR-15 to defend Obama mural

[Clames]

85. I'll let the pictures do the talking. I've found pictures to be more effective when dealing...

...with those of limited technical ability. This will serve as a general technical primer for the RKBA group as a whole and help to dispel the ignorant statement of "easily converted" AR15's made by those who don't do their proper research.

This is a picture of a current issued M16A2 lower receiver showing the select-fire trigger group.


This is a picture of a civilian AR15 "high shelf" lower receiver showing the semi-auto only trigger group.


Pay special attention to the areas forward and around of the rear receiver pin. Notice the amount of material left on the sides and in the bottom of the trigger group "well" in the civilian legal AR15. Difficult to tell in the photos but if measured directly the width of the gap allowed for the rear lug of the upper receiver is slightly smaller in the AR15. This means that a M16 upper cannot be simply installed on a civilian AR15 lower without grinding the rear lug narrower. It is also impossible to swap trigger groups without significant and precise machining to the civilian lower receiver. That isn't all though.

This the a picture of the rear section of a M16A2 upper receiver.


This is a picture of a civilian AR15 upper receiver intended to be installed on a civilian AR15 lower.


The difference is in the depth of the rear lug. The M16's is slightly deeper which moves the position of the hole for the pin down relative to the shelf of the upper receiver. You would have to grind the bottom of the lug and wallow out the hole to make it fit on a current civilian AR15 lower resulting in an unstable, inaccurate, and potentially dangerous weapon to use as there will be excessive play from the modifications to the M16 upper. Military contract M16/M4's are sized to have fairly loose tolerances which makes it easier to field strip, correct malfunctions under duress, and facilitate unit level repair by allowing parts to be swapped from weapons made by different contractors. Civilian AR15's are built to closer tolerances for enhanced accuracy and feel and assembling parts usually requires minor to moderate fitting to work properly.