These Caliber Conversions contain all the parts necessary to change your firearm from it's existing caliber down to the inexpensive .22LR rimfire cartridge. The conversion takes less than a minute. It is achieved with no permanent alterations to your firearm. It can be quickly returned to it's original caliber. They allow semi-auto .22LR fire in semi-auto guns or select-fire operation in select-fire guns.
The "Atchisson" MKIII AR15 .22LR Conversion Unit
From the "Official Site"
CONTENTS: The unit consists of a sub-caliber bolt/chamber adapter/return spring and guide rod/receiver rail assembly and magazine in a fitted plastic case that replaces the standard bolt/bolt carrier assembly in the AR15/M16 family of rifles.
FITS: The unit fits all AR15 and M16 family firearms whose dimensional tolerances meet those of the U.S. Government prints including current post ban firearms.
AR15 Unit - Standard sub-caliber bolt/chamber adapter/return spring and guide rod/receiver rail assemble with 10 round magazine. The M16 unit's 30 round magazine is optional at additional $40.00 upgrade charge.
M16 Unit - Standard sub-caliber bolt/chamber adapter/return spring and guide rod/receiver rail assemble with 30 round magazine with the addition of the automatic trip and anti-bounce weight necessary to support the automatic fire mode of the parent firearm.
OPERATING PRINCIPLE: Direct blow back design, as are all other .22 firearms.
INSTALLATION: Field strip the firearm as you would for cleaning to include removal of the standard bolt/bolt carrier assembly. Install the unit's sub-caliber assemble, close the firearm and insert the unit's magazine. Approximate conversion time is ten seconds.
FUNCTIONING: The unit functions FLAWLESSLY (guaranteed) on good quality High Velocity .22 LR ammunition.
ACCURACY: The accuracy of the firearm it is installed in is maintained out to 100 meters as the .22 bullet runs in the same bore as did the parent rifles standard cartridge. The point of impact is lower out past 100 meters.
MAGAZINE: The magazine's capacity is 10 (30 optional) rounds for the AR15 unit and 30 rounds for the M16 unit.
PLASTIC STORAGE BOX: The unit's box allows for the storage of the original parts from the firearm it is installed on while the unit is in use.
DIS-ASSEMBLE FOR CLEANING (FIELD STRIPPING):
Sub-caliber bolt/chamber adapter/return spring and guide rod/receiver rail assemble - By simple drawing the bolt to the rear the unit may be fully cleaned. This assemble should not be dis-assemble as mis-alignment of the legs of the receiver rail may occur.
Magazine - The unit magazine fully dis-assembles in seconds by removing the floor plate. Parent firearm - The unit should be removed from the firearm after 500 rounds and the bolt locking lug area of the barrel cleaned and de-carboned using the standard chamber/locking lug cleaning brush. Firing the 5.56mm (.223 Rem.) cartridge will fully clean any residual .22LR rimfire ammunition fouling from the gas system.
Sub-caliber bolt/chamber adapter/return spring and guide rod/receiver rail assemble - 4130/4140 Chromoly steel, heat treated as required.
Magazine and minor parts - Cold roll steel.
FINISH: Mil-Spec Parkerized.
WEIGHT: The unit weighs approximately 1 lb. without the plastic box, 1.25 lb. in its box.
MANUFACTURER: Virtually all of the parts of the units are manufactured in our facility in Cape Canaveral, Florida. The kits are assembled, tested, and shipped daily. Truly "Made in the U.S.A." with quality and pride.