Milled rear sight on No4 MK 1

[kb1903]

I have a No 4 Savage with a milled rear sight. I have a good 100 yrd zero on it using HXP ball ammo. I lent it to a friend to shoot a 200 yard match, and he said that he had to come up about 12 clicks to get it zeroed at 200. Is this about right? How much does each "click" of the rear adjustment move the point of impact in minutes?, 1/4, 1/2? inquiring minds need to know. By the way, this is a very accurate rifle. Thanks for the help. Ken

[Sunray]

12 clicks sounds like a lot to me.
The micrometer rear sight? Front blade match the rear sight height? What ammo is he using?

[Art]

If your zero centers the front blade in the bull (half circle) at 100 yarts and his is a 6 O'clock hold on a target like the SR at 200 yards 12 clicks sounds very plausible. Where you hold makes a big difference on that stuff. The battle sight is set for 200 yards. I find with .303 ball or equivalent if I hold at 6 O'clock on a 100 yard SR 1 bull I hit dead center with a dead center hold on the bull at 200, of course everybodies results vary.

[John Sukey]

Art has a very good point. The british aim at the centre of the bullseye while Americans aim at the six 0 clock.

[kb1903]

I believe he and I both held at 6. My main question is on the milled rear sight, how much in minutes does each click on the elevation adjustment move the impact? Is each click a 1/2 minute, 1/4 minute, etc.? I know that the 303 is alittle different ballistically than the 30.06, but 3 feet low at 200 with a 100 yard zero seems way out of the ordinary. Thanks, Ken

[Parashooter]

The answer to your question depends on the specific "milled" sight you have installed - the normal 1300-yard No.4 Mk.1 or the 800-yard sight made for the No.5 Mk.1.

On measuring the two types, each click of the No.4's sight moves the slide .008" - vs. .0043" on the No.5's sight. Consequently, the 1300-yard sight gives very close to 1.0 MOA per click with the No.4 rifle's 28" sight radius while the 800-yard sight has a click value of ~0.66 MOA with the No.5's 23" sight radius and would yield ~0.55 MOA on a No.4 rifle.

http://www.milsurps.com/images/imported/2013/08/2943p13-1.jpg
(Given the slightly coarser thread on the 800-yard sight, the "click value" would be some 10% greater than the 1300-yard sight if both were mounted on rifles with the same sight radius - except for the fact that the 1300-yard elevation screw is double-threaded, giving it an effective pitch approximately double that of the single-thread 800-yard screw.)

The discrepancy between results for two different shooters with aperture and post sights should be no great surprise. The difference in impact between one who centers the bull in the aperture and another who centers the top of the post can account for much of the 12 MOA (24" @ 200 yards) reported. Bullet drop from 100 to 200 gives about 3 MOA (6"). Lighting conditions (sun vs. cloud) can easily yield another 2+ MOA, as can the difference between a "flat tire" 6:00 hold and a "line of white".

[kb1903]

Parashooter, thank you for your very clear answer. I have no idea why my friend had to come up 12 clicks from my 100 yard zero as he said that he did use a 6/oclock hold as I do. He did say that the stock was smacking him very hard on his upper lip. I think he had a cheek weld placement issue which would certainly influence his eye placement/ bullet impact on target. Thanks again for our response. Ken

[Parashooter]

Here's a sketch to help show how two shooters, both using a "6:00 hold", can get very different points of impact at the same sight setting.

http://i58.tinypic.com/vqtn3s.jpg

If your friend is getting smacked in the lip by an issued Lee-Enfield stock, he's got a very strange position (or a really odd lip). It's also likely pain is making him flinch and throw shots low (anticipating recoil).

[phil441]

In 1961 the USAF taught the post centered "flat tire" hold a as a proper 6 O'clock hold so interpretations can vary widely depending on when and where the shooter was trained.