Quoted:
RayDBones
You might want to have a closer look.
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Now you made me go rooting around in both safes (like I need an excuse!!). What I found is very interesting.
My Colt Sporter Match HBAR (A2 upper with 20" heavy bbl - large hole) does not have the extended feed ramps milled into the barrel extension or into the receiver.
Both my Colt Sporter Lightweight's (A2 uppers with 16" bbls - small hole) DO HAVE the extended feed ramps milled into BOTH the barrel extension and the receiver as in the photo above.
Both my Colt "M4" uppers (the real deal - 14.5" machine gun uppers - small hole) DO HAVE the extended feed ramps in BOTH the barrel extension and the receiver as in the photo.
As expected, the RRA LAR-15 and the Bushmaster XM15-E2S DO NOT have extended feed ramps.
So now the question becomes - are the feed ramp extensions found only on the Colt small hole uppers as my small sample size would suggest or is there some other explaination??? Or are they only on the small hole 16" and shorter barreled uppers to combat bolt bounce as suggested above?? Or is it some other mystery Colt has added to their guns to make yet another variation?? Large hole/small hole; big pins/small pins; sear block/no sear block; lug/no lug; and now feed ramps/no feed ramps!!!!! What will they think of next?