Who said anything about beating it with a hammer? I doubt it was beaten together with a hammer.
I just suspect the op is handling it rather daintily.
There's also plenty of evidence that suggests slop causes piss poor accuracy.
Go ahead and replace your take down and pivot pin with something smaller so she's nice and loose, take a trip to the range and report back here please.
While you're at it, shove a McGowan or something into some sloppy norninco and post up the sub half moa groups.
Also, take one of your sloppy ride does, dry fire it and watch for the receiver to move. And you will see it move.
How much movement does it take for you to see. What does that work out to overall fore to aft degreewise. 1/10 of a degree? 1/20th? If you can see it move its most certainly a measurable amount.
That upper begins its jolt the instant the hammer touches the firing pin, then the pin hits the primer, primer ignights, poster ignights, Bullet begins traveling and finally exits.
Between the time you pull the trigger and the bullet exits, things have moved ever so slightly.
There's 60 moa in one degree. 1/10 of a degree represents 6 moa. 1/20 is 3moa.
How much slop you have is going to effect accuracy.
I won't tolerate any play, at all, period.
Now back to the hammering thing. There is a difference between gentle whacks with a rubber mallet and the greatly exaggerated sledgehammering you came up with.
My rifles get banned around enough they would only be so lucky if the worst they saw was a rubber mallet.
And for the record, if I bought a brand new truck that had an issue that I could resolve myself at home within 5 minutes, I'd just fix it.
Filing the buffer tube to the correct profile is not a modification to the rifle btw.