Questions and Answers...
When should a shim be installed?
When receiver play is noticeable it's probably time to install 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. The NM Shim removes play and helps to prevent components from getting a running start and slamming into each other during recoil.
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 average interchangeable commercial receivers has a competitive limit.
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. 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.
What can be done if the recess/sear relief is too deep for the shim?
Usually this can happen with no-brand upper receivers or blems that are not mil-spec in the area of the sear relief. The only remedy is to gauge the relief depth before purchasing a no-brand or purchase a name brand receiver such as Aero Precision, Anderson, Spikes, etc.
Will the shim tighten .308 upper receivers?
The shim will tighten .308 receivers that have the AR15 upper receiver recess/sear relief dimensions shown on the Installation Basics Page.
Is there any the difference between the NM Shim and AR15AccuShim?
Other than one is stamped AS and the other is stamped NM the shims are the same.
Can the shim be purchased separately?
The shim is available only in a kit complete with hardware and installation instructions.
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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