We get asked about putting brakes on the NEF Ultra.
There is the concept called the internal brake that works
nearly as good as expansion brake, with less back noise.
Rob on AR did a couple with bunch of holes in the barrel
in the end with the last 1.5" bored out .025" where holes
go. Also many want more velocity in NEf and I added on
a barrel section to mine. Combining Ideas we add smooth
9" section of bore extension, that is same as groove diameter
and 1.5" end of that for internal brake. Eight 1/8" holes
top and same 45 degees to each side.And we have over
a 100 fps in velocity gain. And with card or wad behind load
it will seal pressure going from rifled section to smooth.
And these types of holes won't bother wads or sabots.
My extension is a foot longer and gets 150 fps extra.
No need for brake in mine as the gun is 17 lbs with extra bbl.
Here is Rob's two he fixed up, and is shooting.He has
them reamed out longer for long 3.85" case, weight added.Ed