Problem With SSA Sticking in Chamber

I have had a problem with ssa 6.8 110 pro hunter round as a box of them will not feed into the chamber and will get stuck, I was hoping it was not the upper and after a go guide fit the chamber I was convienced it was the ammo. one of the 15 i had on hand fit into the chamber and ejected with no problems. I still have not fired it yet as it is driving me crazy, but my problem might be the with the casings. I just got home and yes a box of rounds were sticking, and now after i got home more than three boxes were sticking I randomly pulled 6 rounds from 6 more boxes and they stuck. Everyone of the soft points were marred but i expect that from the feed ramps, but each one of the copper jackets have the same nicks and scratches in the same pattern. So I took a 30 caliber brush and gently pushed in into the chamber to try to remove any burrs or extra metal. After that I flushed out the chamber with gun scrubber and recleaned and oiled the bore and chamber. I ran a random box of soft points, the first on fed so i cycled the gun twice more and the third stuck. after pulling it out i loaded 8rnds total and all of them cycled. Of course the SP are nicked up, but so are the copper jackets. They seem to be feeding smoother, but could a bur or anything else be the cause of this? Their is a pattern of an arch on the jackets and the marred soft points. The first two starts on the left and runs to the right down the jacket and the third fourth fifth and sixth all have deeper gouges as well as the run on the other side. The second to last on the right side has four nicks that you can see running down the jacket. As I fed 12 more from the same box all of them have similar markings one of them has a piece of the jacket looking like a thin piece of metal was shaved off, and that same round has three nicks on the shoulder of the casing. But the FACT Remains, some of the ammo feeds consistently, and some do not it is as of right now around three of every twenty that are jamming. Over pressure can be a real problem here can it not? Is it safe to shoot any of this stuff? I really need to go sight in my rifle asap. So is this ammo, or chamber? the Go guide should be larger than the bullet right? Thanks for your help.