Need shotgun help; feeding issues

[Indy_Guy_77]

Not too terribly long ago, I detailed a problem that I'm having with my Rem 870 12ga.

To summarize; I'm having feeding issues that are related to the previous owner's installation of a magazine tube extension.

The spring is getting hung up under the compression of rounds 5 and 6 and won't un-snag unless I take the extension off and let the spring sproing out.

Evidently my shotgun came from the factory with "dimples" on the end of the stock magazine tube in order to discourage (by causing the spring to hang up, imagine that!?) the addition of extensions. Remedy: remove the dimples by drilling them out. Previous owner did so. Kind of.

It was suggested, and I belive quite rightly so, that I attempt to file down the interior of the drilled out holes in order to, hopefully, get rid of spots that might be causing the problem.

I did that...and I'm still having issues with the spring hanging.

I COULD file more, but honestly, I'm afraid of boogering the thing up even further and REALLY rendering the thing useless.

In short, I could use some hands-on help in determining what the exact problem is and when I should stop filing?

Can any shotgun gurus on the south side help a feller out? I'll pay you!

Thanks,

-J-