Indeed fire-lapping will facilitate not only your break-in process but uniform the bore and remove any constrictions in the barrel. As an added bonus, once finished the barrel will not have the propensity to copper foul, especially if shooting Barnes X-bullets.
More than likely, 30-40 lap loads will be sufficient. Be sure to spend the time necessary for the final polishing of the bore as outlined in the Beartooth Bullets Technical Guide. It will make the difference when it comes to fouling reduction. A charge of 5.5g of Red Dot or 5.2g Bullseye should make a fine lapping bullet charge for your 7mm Remington Magnum.
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