I picked up a case of Estate 1 1/8oz, #6's, that are 1300fps, at a store close out a couple weeks ago. I shot a box of them with my Belgian mag 12 and they cycled and shot well. When I switch to using my "new to me" jap mag 12, it would cycle them about 75% of the time. I took the Jap gun all the way down after I got it and examined it. The friction rings are all good, mag tube is very clean, recoil spring is good, and I replaced the action spring. Comparing the two guns, the Belgian has the double recoil spring, whereas the Jap has the single. Seems to me that it should cycle the 1 1/8oz ammo but, there's an obvious difference between the guns. Or is this brand of ammo just borderline for functioning in these set ups?