30" left on brit

[pelago]

n4 mk1, 1942

a full 30 inches left at 200 yards

is this correctable with adjust ments of front sight
this is measured at range and with a 6 oclock hold it hits that far left

fixable?


'

[Parashooter]

Move the front sight ~.135" left. If you run out of dovetail, check bedding and barrel timing.

[John Sukey]

Might also want to check if the fore end is bearing on one side of the barrel.

[pelago]

barrel timing.

okay, now you have me, and completely i might add

[Parashooter]

Barrel timing means how far the barrel is screwed into the receiver. If it's off, the front sight assembly may be tilted rather than centered .

[Fred]

Isn't that where the two marks come in that should be aligned on the side of the barrel and receiver?

[Parashooter]

Assuming the marks are in the right places. Maybe so, maybe not.

[Sunray]

Milsurp from a reliable milsurp dealer(Century is not), bubba'd or rebuilt bubba'd rifle?
30" left at 200 is a lot. You won't be able to adjust the front sight that much. Assuming the front sight is centered and not bent or otherwise damaged, itself.
I'd start by bore sighting it. No pricey tools required. Take out the bolt, put the rifle on a flat surface, sight on some object about 100 yards away, then look through the barrel. If they don't match, and I'm guessing they won't, the sights and barrel are off. Next, take the stock off and put a straight edge on it. Looking for a bent barrel. Possible, but not likely. Then look at the indexing. Put the rifle, without the stock, in a padded vise. Use a 6" level on the charger guide to get the rifle level, then put the level on the flat part of the chamber or on the front sight wings. That'll tell you if the barrel is canted and, therefore, not installed properly.
"...Move the front sight ~.135" left...." Absolutely not. Front sights get adjusted in the opposite direction you want the group to go.
Headspace OK? Nothing to do with the sighting, but check that first if you haven't already.

[Parashooter]

"...Move the front sight ~.135" left...." Absolutely not. Front sights get adjusted in the opposite direction you want the group to go.


I think he's saying it's hitting 30" left (". . . with a 6 oclock hold it hits that far left"). I imagine he'd like the group to go right. As you indicate, that will require moving the front sight in the opposite direction - left.

[Sunray]

"...think he's saying it's hitting 30" left..." DOH! When I pay attention, I don't say silly(stupid, really) things like that. My apologies.
How do you figure ~.135"? Doubt that'd move the group 30" at 200.

[pelago]

it is hitting left all right, i shot it at butner last year, and first roung at 200 prone was a miss at 9 between two target frames, just missed the wood frame, held a "imaginary" 6 hold on "imaginary bull at 3 oclock just off frame and hit dead center bull......

was intersting day

holding a 6 oclock sight picture on air!!

wondering if it is in fact the barrel just no on right, have not head spaced it nor checked, but if front sight is cocked that could be culprit, if cocked due to barrel not being screwed in
who knows???, nor have i checked wood to metal pressure, but it shoots too far (i think) to be that

[Parashooter]

How do you figure ~.135"? Doubt that'd move the group 30" at 200.

Easy as 1-2-3-4 -

1. To find the distance to move the sight for a ONE minute change,
2. Measure the distance between the TWO sights (front and rear),
3. Multiply that number (sight radius) by THREE,
4. Move the decimal point FOUR places left.

Sight radius of the No. 4 rifle is about 30", so 30 x 3 = 90, and moving the decimal four places left gives .0090". Pelago wants a 15 MOA change in impact (30" at 200 yards). 15 x .009" = 0.135"

This is just simplified trigonometry. The tangent of a one-minute angle is ~0.0002909177488 - close enough to .0003 for the "1-2-3-4" mnemonic to be practical. If we use the true value, and the actual 28.4" No.4 sight-radius, we get 0.124" for a 15 MOA change.

FWIW, 0.124 is just a split hair under 1/8". That amount of movement is easily possible with the No.4 front sight unless it's already sitting far left on the sight base.

[pelago]

I aim at 6 oclock and impact is full 30 inches left