Need help from any familiar with the 347 or related models of benji.... struggling with my 1972 347. Trying to get the first chamber nut unscrewed with the square tool. wd 40 overnight but still no budge manually. Have not tried a vice yet. One vid on youtube the guy just placed it and turned.... mine, however, is not rotating loose. This gun was never left outside, always indoor closet with AC. But time is time, and likely some thread corrosion or rust. Just need tips from what work for others. thx