New guy with a new GBL and some questions

First time poster ... long time lurker Finally got myself a Marlin and have a reason to post .
I have read all the horror stories of the Marlingtons and was a bit worried about buying one, but decided to take my chances because I just wanted this gun so bad .
So my local shop had 6 GBL's in stock, I was able to handle them all and found one that seemed to be flawless, so it followed me home ;D
So, all seemed well when I took it out shooting this past weekend . At first I was shooting some 405 grain Remington express and it was cycling them great and seemed to be shooting great at 25 and 50 yard targets .
Then I tried some 325 grain Hornady leverevolutions ... They shoot well, but wouldnt cycle for me ? They would come back out of the tube mag and the follower (i think thats what its called) would kick the round up and it would stick half chambered on an angle not allowing the bolt to close ? the only way it would work is if I tipped the gun over allowing the round to chamber and close the bolt .
Is this an issue with the gun ? or is it more of an ammo thing because of the pointed tip and I also noticed the case itself is slightly shorter than the Remington stuff ?
The second question is .... after shooting it, I seen what looked like tiny flakes of brass inside the barrel ? spotted a few just inside the crown area ... after a closer look down the barrel, the whole inside barrel was coated in this stuff ? looked like somebody took a salt shaker to the inside of the barrel ... and inside the bolt area had this stuff that looked like gold or brass glitter as well ? is this normal ? never seen anything like this in my other rifle ? I ran a patch through the barrel to get rid of it ... took another shot, and it was back ? Is this normal ? or did I get myself a Marlington dud ???
Sorry if these are dumb questions, but Im not only new to Marlins, but to guns in general ..

Thanks for any input