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5,714 Posts
Discussion Starter · #1 ·

1.) Op-Rod Specs;
a.) Piston Dia.; Min. Diameter- 0.5256
b.) Out of Round; No more than .00035
c.) Tab specs; Height- .320(min..317), Width-.250, Thickness-.100(Min..097)

2.) Gas-Cylinder Front-end; 0.532

3.) Gas-Port; 30-06-.079(use #47 drill bit to check, No-Go is #45 bit)
.308- A little nebulous. Depending on Manufacturer anywhere from .096 to .107.

4.) Sight adjustments(Come-ups) Based on 100 yard zero.
a.) 200 yards-two clicks up from 100 yard zero
b.) 300 yards-five clicks up from 100 yard zero
c.) 500 yards- twelve clicks up from 100 yard zero
d.) 600 yards- sixteen clicks up from 100 yard zero

5.) Targeting front sight
a.) sight correction with M1 Garand is .008= 1-inch at 100 yards
b.) Formula; (Sight Radius in inches)x(Impact point distance from point of aim)/(Range to target in yards)x(36” per yard)=sight correction.
c.) (28”,sight radius of M1)x(1” from point of aim)/(100 yards)x(36)=.008
d.) Say you need 18 clicks of elevation to zero at one-hundred yards. Optimal
Elevation amount is six clicks for proper use of sight. So;
(28” times 12{18 clicks minus 6}/(100 times 36)= .093
So, filing the front sight down by .093 will put you at zero with six clicks at 100 yards. This is assuming proper trigger-guard tension and a tight lower-band(Both have the effect of raising point of impact through loss of downward pressure).

6.) Checking Lubrication through ejection
a.) Properly lubed- First seven rounds between 1 O’Clock and 2:30(barrel direction is 12:00),with round #8 at 3:00.
b.) Ejection at 12:00 to less than 1:00- Over-lubricated
c.) Ejection past 2:30- Under-Lubed or dirty

7.) Grease-Lube point on Garand
a.) Bottom of barrel from 1” in front of receiver to 3”.
b.) Op-rod Tab Track
c.) Camming Surface in Hump of Op-rod
d.) Bolt-camming lug on Hammer
e.) Inside rear-lip of receiver
f.) Locking recesses of receiver(Bolt-lug slots)

5,714 Posts
Discussion Starter · #2 ·

Op-Rod Spring- Min. length 19.5 inches long,Max. length 21.25 inches, 1/8th" center to center on coils, no kinks or flat spots. When installing liberally grease first four to five inches.

Hammer Spring-2-3/8" long min.

Roll pin replacement for Lower Band- Dia.x Length-1/8th"x1/2"

Sources for above posts and more info; Tap's Tips( I copied alot of them), FM23-5, TM9-1275.
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