I am looking at the Robinson XCR and was wondering if anyone was aware of any factory/aftermarket shortened barrels or whether ADCO or any of the other great shops have any experince cutting these thin barrels down.  I would also like advice on barrel length.  I will be SBRing the gun and will likely add an AAC FH to work with my AAC M4-2000.  I am also seeing posts about a Robinson gas valve?  Is that mod required to allow consistent feeding/action for suppressed fire?  Any pics or advice would be greatly appreciated.

As far as I know Alex Robinson makes a 10.5" pencil bbl. for law enforcement already.  Call and find out if they will sell you one.  Barrels are not restricted to FFL so there shouldn't be a problem.  I have the new suppressor gas valve but you don' need it for reliability.  The standard gas valve that comes on the rifle now, will work just fine on the #1 setting.  The suppressor gas valve has a #1 orifice that is much smaller thus eliminating ALL blow-back and greatly reduced recoil.  If you are going to take the suppressor on and off a lot you will want to set the gas valve to reliably cycle your chosen ammo without the suppressor.  That way when you put the suppressor on it will still work but with just a little blow-back.  If the suppressor is going to stay on all the time then use the #1 suppressor setting for minimum recoil and no blow-back.  I was using my AAC Ranger on my XCR but with the 16" bbl. it is a little long for my taste.  My suppressor now lives on a 10.5" AR upper.  I am not going to get a short barrel for my XCR because I do not want to keep it as a title I weapon and can therefore take it from state to state without informing ATF.  I currently use mine for 3-Gun Tac Matches.

MadDog