so like many of you, i have had chopping issues with my rpm.
after breaking the barb on my 3-way, it sat around in parts for a few weeks until i found the amazingness of jb weld

. after putting it back together and checking for leaks i went ahead with additional testing. after 3 different hoppers and many different barrels i was still chopping during rapid fire.
so here's what i did.
first definitely go to warp8nt's page. i noticed many of my breaks were due to an insufficiently chamfered barrel.
next if you look down the feedneck, you will notice the bolt sits a bit back of the breech opening, allowing another ball to partially protrude. so i added another o-ring to the ram closing this distance, and just in case shaved the top portion of my bolt like how angel bolts are done.
pictures will be up later.
cliffnotes:
visit rpmowners.com
chamfer barrel
remove detent
add o-ring on ram
shave a little bit off the top of the bolt