Originally Posted By backbencher:
The engineers I met in Iraq w/ the collapsible stock A2s had them done by their unit armorer.  So maybe we're getting better.  

All above references to "the Marine Corps Shooting Team" input as to stock length or anything else re the A2 improvements is pure BS.
We developers checked out the man-machine interfaces of the A1 with the Army's Human Engineering Lab early in the A2 program (1980-83).  They had data that supported adding 1 inch to the length of pull to beter fit the 5th to the 95th centile Soldier.  However, adding a full inch created issues with standad armory rifle racks, ship board racks (some),etc.  So we limited the increased length to 5/8".

This lenght of pull data composites body size, arm length, ideal eye position behind the peep sight, body armor thickness of that era, etc.  So we asumed it was correct.  Our Operational Testing (part of which was "hosted" by Quantico's Weapons Traing Battalion, i.e., MC Shooting Team) proved this out, or at least did not find any deficiencies with it.  The Test Officer, Major Bruce Winshenesen (sp) was a foremr Rifle Team member, rated Distinguished Marksman, etc., but was then asigned to us at the Development Center.  Bruce was very efective in getting the Quantico belly shooters to cooperate with the support, ranges, personnel, etc., we needed, but at end-game, all their input such as for a full-length heavy barrel were rejected.  Testing used two Marine Corps Rifle Squads and one from the Army at Ft. Benning.

The added-length design we selected (buttstock spacer on top of the old standard length receiver extension (i.e., buffer tube) was deliberatly selected so M16A1 length butstocks and screws could be substituded for the shooters outside the 5th to the 9th, or when the bulk of cold weather clothing was added to the matrix.  However, since no M16A1 length buttsocks of the improved zytell material, larger cleanng gear compatment, etc., improvements to the new longer buttstock were ever stocked or supplied in the "system," that option seems to have slipped into obscurity.

However, the Canadian Laisison Officer who shared my ofice at Picatinny during that period picked up on this and it was adopted/institutionalized to supportthe C7 rifles for their Army for althose reasons to include smaller stature women shooters.
Even considering the many contrary opinions re the increased length, think about it this way.  In 1983 we could just as easily made the buffer tube 5/8" longer, kept the M16A1 (shorter) length buttstock screw, not then needing the A2 spacer.  I mean if we had done it that way (which had some support from the Logistics tail) then we'd all be fox trotted up with no other option but to switchout the bubfer tube.