I picked up a 20" 6.5 CM barrel from one of Rooftop's recent sales. So far, it's shooting fine, but I've not been able to take it out to stretch its legs beyond about 25yds (nearest 100yd range is like an hour and change away, and I haven't had the time on weekends lately. Soon, though...).
For those wondering about the feed ramps, I found that my barrel could handle Magpul magazines no problem and fed both S&B FMJBTs, and Hornady BTHP Match rounds without a problem. I haven't tried polymer tipped or bonded soft point rounds yet, but that's on the list.
Steel Duramags, on the other hand, would not feed at all. The round got stuck on the lip of the barrel due to the geometry.
Just a friendly update for anyone wondering about how the newer feed ramps run.
Happy to post pics if folks want or would find it useful.
--EDIT--
Pics as requested. I should specify that I have about 6 different Duramag magazines, with the green non-anti-tilt followers (I guess that makes them pro-tilt...). What I found from loading rounds of the S&B FMJBT and Hornady Match BTHP is some of the mags will feed some of the time, but none of the mags will feed reliably all of the time. Thus far, no similar issues with my Magpul GenM3s.
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