Necessary Modifications and Associated Parts,
M^cPherson Buttstock Throughbolt System

· Upper and Lower Tangs

o To accept specially-threaded, larger, hardened-steel, Tang Bolt

· Matching Tang Bolt

o Will not permanently deform under normal throughbolt loading, extra fine threads strengthen attachment to lower tang

· Hanger

o High-strength steel, allowing smallest feasible hole through buttstock

· Throughbolt

o Fine thread, high-strength, to easily provide adequate clamping force (maximum feasible clamping force in Walnut exceeds 2000 pounds!)

· Throughbolt washer

o Transfers load to epoxy-reinforced shoulder in buttstock

· Buttstock

o Fully glass bedded to receiver and to throughbolt support washer

o Fully sealed, inside and out

o Modified, to accommodate throughbolt, hanger, and tang bolt

Instructions for Stock Removal

· Remove recoil pad or buttplate

o Always uses two screws, usually Phillips (if screw head is hidden and no plug exists in pad, pulling pad face sideways will expose access slot to screw head – with this system, apply a dab of liquid soap to end of shank of a #1 Phillips screwdriver so that it freely enters and turns in pad without damaging pad)

· While noting how tight the throughbolt was (see below), loosen throughbolt using 7/16-inch socket on extension with ratchet or speed-handle

· Remove tang bolt

· Remove stock (may require modest force, wiggling up and down will help)

Instructions for Reassembly

· Install stock

· Assure that hanger is in place

· Install tang bolt

· Tighten tang bolt very snugly — not necessarily as tight as may be possible using a typical screwdriver but very tightly. Then tighten throughbolt (to about fifteen-foot-pounds of torque)

· Install keyed recoil pad or buttplate

Warning: It is possible to destroy the gun by over-tightening the throughbolt; by doing so, you can permanently deform or break one or both of the tangs!

Conversely: Insufficient tightening renders this system less effective. When originally assembled, the throughbolt was properly tightened. It should stay about that same tightness (unless the wood shrinks significantly along the grain, which rarely happens).

Correct Throughbolt Tightness: About fifteen-foot-pounds of torque is a reasonable tightness. Adept tinkers can readily feel when this bolt is tightened correctly because turning force will suddenly begin to increase sharply at the point where all slack is removed from the system, do not tighten significantly beyond this point — perhaps one-half turn but no more.