got a bushy A2 Shorty carbine. It has some wobble where the stock meets the receiver. I think it's just the way they"re designed. Is there a fix to tighten this area where the upper pins to the lower. I heard someone uses an O ring to fill this gap but to me thats just temporairy and just a matter of time till the O ring works it's way out or gets chewed up. Anyone know of a fix or am I destined to live with this. Also, I do believe this is common on all AR"s or copies.