January 1st, 2007, 12:13 PM
Join Date: May 2006
Location: kerrville. texas
| | M1A bolt lapping instructions
This procedrure should ONLY be done if you do not have bolt roller receiver rail impact. Read The Sticky on Roller Impact first.
Equipment needed: 600 and 800 lapping compound, small screw driver, 1/8" tip, broad tip black felt pen, fine steel wool, soft jaw vise and punch that will fit ext. hole in bolt. Tool to cut case in half.
Disassemble rifle and strip bolt, clean all lube off reciever and bolt surfaces. Pick several cases fired in this rifle, if one will still fit in chamber it's the one to use. If none will fit, resize several and clean with sreel wool , clean thoroughly. Deburr rims and case mouths.
Cut selected case in half, one inch up from base. deburr cut area. Take the hammer spring out of your trigger group and put it between the two halves of the case. Insert this unit into the chamber, there will be over hang, thats ok.
Put a good coat of black ink on the back of the bolt lugs, put the bolt into the rifle, insert the punch into the ext. hole and push the bolt into the full lock position, if there is too much pressure find another spring that will work, one that offers strong drive back pressure on the bolt face. Using the punch as a rachet, work the bolt open and closed in short strokes, not to ride over the top of rec. rail. Do this 10 or 12 times and remove bolt. You can read the displaced ink on bolt lugs and see which one is getting the most load, it's the longer of the two.
Remove the bolt,, with the screw driver, spread a smooth thin coat of 600 compoumd on the rec, recoil lugs, not on the bolt lugs,
don't let the compound get into other places as you put it back into the rifle. Hold the punch firmly and run the bolt into full lock position. Work bolt up and down as before 10 to 20 times and remove, clean all compound off bolt and rec. Read the back of the bolt lugs, the new shinny surface is the lapping. Repeat this procedure until approx. 60 to 65% of the lug surface is new, now change to the 800 compound and repeat until 75 to 80% is new. Do not try to go farther , this is pleny and the job is complete, Clean up, lube, put the rifle together and you have a save and better weapon.
If some of this is unclear, and there maybe some grey areas, drop me a line, Art Luppino