current barrel is the 9" (probably discontinued for this reason). normally never go below 10.3 but the trade was too good to pass up for a full upper. Have the longer piston but not sure if a 10.3 barrel uses that and longer op rod or not. Ideally I'd like to keep current barrel since still in the 2600fps range with m193. Have adjustable gas block getting imported in next 2 months as well. Think I need a new barrel and op rod to prevent this and be more reliable or wait for the AGB to come in and hope it doesn't do same thing? HK nuts I'm open to any suggestions. Trying to save the money where I can and not buy a bunch of expensive stuff that won't work.