I have a good friend that is selling a DPMS SASS (AR-10 clone) heavy barrel 308. I'm considering buying it, but I will want to run a Surefire or Gemtec suppressor on it. I know that the LaRue tactical AR-10 has a gas adjustment valve on the gas block, but I can't find any such system with the DPMS. For those of you that run AR-10 style rifles, are you having a problem with too much gas blowback when using a suppressor? Does anyone know of an adjustable gas block that can be installed on the DPMS if it is needed?