Using a M5 RAS on a Bushmaster Dissipater Upper
for a Larger Image!
M5 RAS on Dissipator by compuvette
of AR15.com forums:
I purchased an Knight's
M-5 (full length) RAS and installed it on a Bushmaster Dissipator A3
upper. The RAS fit pretty tight on the HBAR barrel, but
everything works fine. The Bushmaster Barrel actually measures
0.75" which is significantly smaller than the 0.84" that is ideal for
the M5 RAS.
The Dissipator upper
utilizes a functioning gas block with shaved front sight in the normal
carbine position (covered by the full length rifle handguards), adding
a "dummy" gas block/front sight assembly further out on the barrel at
the rifle length position. The functioning shaved gas block did
contact the inner surface of the RAS at the four corners of the shaved
top surface of the gas block. Minor dremel tool modification to
the inner portion of the RAS at the contact points provided complete
clearance of the gas block.
The weight feels fine,
not really different then the stock hand guards. I have a GGG A2
flip-up on the flattop upper receiver and an Eotech 501 mounted about
two slots up on the RAS and an Insight M-3 light mounted on the right
side of the RAS mounted all the way forward.
|O'DubhGhaill, another member of AR15.com advised he has also done this
and has the following advise:
I would suggest that
anyone using the M5 on a Dissipator, clearly not a milspec
barrel assembly, check the gas block corners to inner RAS surface
clearance, as the integrity of the RAS's perfectly straight rail
properties might be compromised whilst the RAS clamp is tightened and
the rail is compressed over the shaved gas block interference. (note:
my RAS returned to its originally perfectly straight condition after
the mod.) Realizing that the M5 is designed and manufactured for use
on 20" milspec barrel assemblies, I am very happy I could make the M5
work on my Dissy with such minor modification, a mod not all Dissies
might require of the M5. I am completely satisfied with the
exceptional quality and performance of the M5 and am thoroughly
enjoying the vast real estate the M5 provides on my 16" Dissy!