Necessary Internal Components To Repair / Build / Rebuild a Custom Rifle
The Geissele AR-15 Lower Parts Kit contains all 17 parts necessary to get your lower receiver operational - minus the trigger and pistol grip. Geissele is renowned for superbly designed, meticulously manufactured products, and these parts meet their high standards. Items in the AR-15 Lower Parts Kit are manufactured to "mil-spec" (M16 / M4) dimensions to ensure optimum fit and function in your AR rifle or carbine.
The Geissele AR-15 Lower Parts Kit includes:
- Bolt catch
- Bolt catch plunger / spring / roll pin
- Mag release
- Mag release button
- Mag release spring
- Buffer retainer spring
- Buffer retainer
- Safety detent & spring
- Triggerguard & roll pin
- Takedown detents & springs
- Pivot / takedown pins
The fire control system - trigger, hammer, disconnector (and pins) - may be the most "personal" part of any custom AR-15. Along with the pistol grip, it’s the area most customizers and custom builders prefer to select very carefully. As a result Geissele omits both components from this AR-15 Lower Parts Kit so you don’t have to spend money on parts you won’t use!
Big Book Catalog, Issue:71, Page:043
Heat treated steel bushings as above, but with the addition of a Titanium Nitride coating to further increase the effective surface hardness and reduce sizing friction. Bushings are available throughout the range of .185" thru .368" in .001" increments. The last three digits of the part (#RD76XXX) denotes bushing size.
Determining Redding Bushing Size
The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or a dial caliper. Then, simply subtract .001" from the cartridge that had the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet.
If you are using a Type “S” style die and not turning the outside of your case necks, we suggest using a bushing .002" smaller than your smallest average neck diameter, and using the expander ball included with your Type “S” die. This size bushing will still give you minimal sizing (maximizing the life of your brass) and the expander ball will insure that each cartridge has the same bullet grip.
Redding has found that when you have cases with neck wall thicknesses on the thin side of the SAAMI tolerance, your fired case will measure considerably larger (.006" to .010" larger) than your loaded rounds. In these circumstances, Redding’s tests have shown that a bushing .001" larger (than the loaded round) may give you the desired bullet grip.
Sinclair, Issue:1B, Page:043