A quick look at this 'offset' retaining pin.. i suppose.. gtaw + er70 and a little time with hand files.. I understand the purpose of this item. That many out of spec receivers circulating for such a part? Alternatively, why could a person not take a large bastard file and slowly remove material from the receiver extension tube itself? Even filedriving should prevent buggering threads. A triangle file at most would be needed for pointing the end of tube threads again. An overly long tu