Let me say I have looked around here and read a few threads.  I even wrote IWI but they didn't respond.  Maybe a dumb question.  Anyway, here goes.  Bought a SF FH for my Tavor so as to use their SOCOM suppressor with it.  I've read about mounting against shims or the jam nut.  For the SF hider, you run out of threading in the device before you do in the barrel.  My gunsmith said he understood the issues and mounted it against the jam nut.  I picked up a set of suppressor alihgnment guages from Geissele.  On all my 7.62 rifles and other 5.56mm rifles the alignment was ideal and looked exactly like it should in the Geissele instructions.  In also looks exactly like it shouldn't in the Tavor.  I'm not planning on tempting fate so want to get this resolved before shooting.


Does anyone know PRECISELY how an SF muzzle device on a Tavor should be mounted in order to maintain alignment through a suppressor?

Thanks.

You need the print / drawing from surefire to determined the correct datum or mounting surface for correct fit.

As an example AAC calls out the face of their mount as the mating surface to the barrel shoulder. Using shims or spacers is not desirable unless you are certain they are parallel to keep the mount perpendicular to the bore axis.

If you are using a surefire mount go by their suggestion or print specs if available.
( I machined a parallel spacer to index my AAC brake)

I used the nut and then spacers for a AAC comp, not Surefire but its the same principal.  Works like a champ.

I used a combination of the surefire color coded shims from two different packages to get mine time correctly on the Tavor.  No issues thus far.

I wasn't comfortable using the jam nut.  My reasoning. Being that at least I could assume the shims from surefire were parallel even if I had to use a greater amount of them than normal.

Thanks everyone.

picture of my solution at bottom of thread:  http://www.ar15.com/forums/t_6_20/429961_Jam_Nut_and_suppressor_mount_on_Tavor.html

if there isn't enough shoulder to properly bottom out the mount, adding stuff in front of that shoulder isn't going to magically change that.    however, you can always get lucky and if you check it with the right tools afterwards, it will be sufficient.   this is the same issue with the SCARS, let the mount bottom out on muzzle, just don't overtorque it.  With Rocksett, you don't even need as much torque as stated in the  mount manuals.   15-20 lbs should be plenty and you could probably get away with closer to 10lbs.