LaRue likely spec's an extension that is about 1000th or so looser than the bore of the receiver to allow for hand removal of the barrel and a carbine style ramp... 3-5 seconds with a torch would get the bat one to seat correctly but then that negates the ability to switch barrels. The tight fit does increase the potential for accuracy assuming that the receiver extension bore is faced correctly. I bet an armalite or dpms carbine extension would be a perfect fit. Using a carbine extension in an upper that doesn't have ramps cut is fine. You might get feeding issues if you use rifle one in an upper that has them cut because it creates a ledge. Either way doesn't matter now because the extension is on the new barrel and you can't swap it after the fact.
We measured all the 308 extensions and bolts in the shop for a project , need to see if I have the notes of what extensions had what spec. Most of them were within a 1000th of each other, but the uppers have a much greater spread depending on the maker and if they were billet or forged
We measured all the 308 extensions and bolts in the shop for a project , need to see if I have the notes of what extensions had what spec. Most of them were within a 1000th of each other, but the uppers have a much greater spread depending on the maker and if they were billet or forged
Last edited:
