andremajic
11-22-2014, 12:54 PM
Ok, so after taking some dimensions of the existing parts I have.
Old bolt head shank (243 win) length 1.125"
New bolt head shank (223 rem) length 1.00"
Old firing pin retaining nut is .625" long
So, to get the dimensions of the part needed:
.625 (Old firing pin extension nut)
+.125 (Difference between new and old bolt shanks)
_____
.750" (Length of new firing pin retaining nut needed)
The reason you need to have a longer firing pin extension nut is to make up for the differences between the length of the old vs. new bolt head shanks.
I turned out the new oversize firing pin extension nut on the lathe from a Stainless steel rod.
Dimensions should be .750" long, by .435" wide, drilled with #3 numerical drill and tapped 1/4-28 TPI
A cross shaped (+) channel was filed into the rear of the nut to retain the washer. (Use old nut as a reference)
Front profile angle copied from old part by holding it in the chuck and setting tool angle to match existing profile.
New bolt head needed to have the shank side drilled out for the .143" firing pin body.
Inside reference nub/nipple of bolt ground out with carbide tipped burr.
Using new firing pin extension nut, adjust firing pin protrusion thru new bolt to .055" and reassemble firing pin assembly, bolt, headspace with GO gauge and barrel, tighten barrel nut, and you're GTG!
I know, needs pics, but hopefully my post helps someone searching in the future.
Andy
Old bolt head shank (243 win) length 1.125"
New bolt head shank (223 rem) length 1.00"
Old firing pin retaining nut is .625" long
So, to get the dimensions of the part needed:
.625 (Old firing pin extension nut)
+.125 (Difference between new and old bolt shanks)
_____
.750" (Length of new firing pin retaining nut needed)
The reason you need to have a longer firing pin extension nut is to make up for the differences between the length of the old vs. new bolt head shanks.
I turned out the new oversize firing pin extension nut on the lathe from a Stainless steel rod.
Dimensions should be .750" long, by .435" wide, drilled with #3 numerical drill and tapped 1/4-28 TPI
A cross shaped (+) channel was filed into the rear of the nut to retain the washer. (Use old nut as a reference)
Front profile angle copied from old part by holding it in the chuck and setting tool angle to match existing profile.
New bolt head needed to have the shank side drilled out for the .143" firing pin body.
Inside reference nub/nipple of bolt ground out with carbide tipped burr.
Using new firing pin extension nut, adjust firing pin protrusion thru new bolt to .055" and reassemble firing pin assembly, bolt, headspace with GO gauge and barrel, tighten barrel nut, and you're GTG!
I know, needs pics, but hopefully my post helps someone searching in the future.
Andy