Questions and Answers...

How much is too much receiver play?
Generally if our shim cannot tighten the receivers there is too much play for installing expensive barrels, triggers, etc. The shim is designed not to tighten receivers with excessive wear or with machining issues. Since play between quality competition matched receivers is zero the play between commercial receivers has a competitive limit. Always gauge receiver play before installing any receiver tightening product. 

When should a shim be installed?
When receiver play is noticeable consider installing a shim or keep a kit for days ahead. Solid mounted free-float handguards, barrel weight, scope weight and fixed stocks can make receiver play more noticeable. Lightweight rifles with two-piece handguards and adjustable stocks can make receiver play less noticeable.

What about an AccuWedge, etc?
If you have an unloaded rifle with an AccuWedge installed simply grasp the upper receiver and grasp the lower receiver and twist. If the receivers have any side to side movement along the seams means the receivers are not tight and right. To tighten receivers requires holding the sides together in a fixture and drilling precise pivot and takedown pin bores like those found in matched receivers. To properly tighten average interchangeable commercial receivers the play between the receiver sides has to be filled in. An AR15AccuShim aligns the receivers and provides rock solid side to side support without altering the original takedown pin configuration. An AccuWedge or a nylon tipped receiver tensioning screw can be used with the shim. O-rings, epoxy, tape, ear plugs and other such remedies are not recommended. Before purchasing a rifle equipped with an AccuWedge remove the AccuWedge and gauge receiver play.

How do you tighten the front of the receivers?
The fit between the upper receiver pivot pin lug and the lower receiver pivot pin ears is often overlooked and the fit should have a slight drag. If machining play is present there are shim washers available that can be installed on each side of the upper receiver pivot pin lug. Also check how well the pivot pin fits the receiver bores and if necessary install an oversize pin. If an excessive amount of wear exists in the area around the pivot pin replace one or both receivers.

Will the shim tighten .308 upper receivers?
The shim does tighten .308 receivers with the upper receiver recess/relief dimensions shown on the Installation Basics Page.

Is there any the difference between the NM Shim and AccuShim?
Only difference is one is stamped AS and the other is stamped NM.

Is the shim guaranteed?
The shim is 100% fully guaranteed to perform as advertised. Should the shim not meet or exceed expectations simply return it for a full refund including return shipping cost.

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