[19809]

1200 grit

use 1200 grit and you may as well lap the lugs while your at it.
The 452's upper lug (bolt open) tends to have less or no contact
than the lower lug. On mine the lower lug is what was causing
most of the problem. It rubs on the sides of the lower groove in
the receiver.

I used 1200 grit on the bolt body and the contact face of the lugs
and a dab of 600 grit on each side of the lower lug as it contacts
the sides of the receiver groove. Use moderation here as you can
remove a little material at a time but you can't add material .

when you done disassemble rifle and the bolt and clean with brake
cleaner and compressed air.

 

[19809]

...and destroy the plastic mag well while you're at it

The bolt on my trainer was tight...for about 500 rounds. I find a brick of ammo is much more enjoyable than lapping

Thats why I recommended that he disassemble the rifle in the first place.

since one of the magwell screws retains the ejector plate
this would be a good time to modify the ejector.

The ejector usually binds/scratches the cleaning rod especially if you
use a rod guide. I modified my scout and trainer and this fixed
the problem.

see my other posts for details ...