Sights: Metric and Inch front sight math

[rschimmelbusch]

Were different front sight posts/heights used on StG58's?

The reason I ask is that my CAI assembled STG shoots about 8" low at 100 yards with the front sight cranked low (don't think I'm bottomed out, though). This front sight post has one dimple between the "0" and the "5", and measures (roughly) just more than 4mm from top of disk to top of post.

On the other hand, a post contained in a kit I bought from Tapco has two dimples between the "0" and the "5" and seems to measure slightly less than 4mm from top of disk to top of post.

Any idea as to the significance of the dimples? Are these heights I've eyeballed against a steel rule just production variances?

[ August 12, 2001: Message edited by: gary.jeter ]

[ August 12, 2001: Message edited by: EMDII ]

[Steve68]

Had the same problem. I called DS ARMS and spoke with a great guy there. Stated that there are 4 front sight posts numbered from 1 to 4. 1 being the shortest post and 4 being the longest. They are $25 each. His advise was to order the one I thought would help, a #1, or just use a file and CAREFULLY and REMOVING JUST A LITTLE MATERIAL, lower the sight. These guys were a pleasure to deal with.


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Steve

[rschimmelbusch]

Thanks for the info, Steve. Have you noticed if they are numbered correspondingly? I don't have either of them out in my hands yet so I've only noticed the dimples on top. I assumed that the dimples were the coding somehow...

CAREFULLY is right!!

~Rich

[gunplumber]

there are actually 5 sizes of austrian. ID'd by no dot, or 1-4 dots. 4 is tallest and zero is shortest.

------------------
T. Mark "Gunplumber" Graham
gunplumber@arizonaresponsesystems.com
Arizona Response Systems
5501 North 7th Avenue, Phoenix, AZ 85013
623-873-1410 http://www.arizonaresponsesystems.com

[EMDII]

The Israeli foresight pins are numbered.

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1*.....Train Like You Fight: Second Place is NOT an Option.

E.M. (Ted) Dannemiller II

[alFALfa]

Regarding Austrian front sight posts, 0=shortest to 4=tallest:

Anyone know what is the height difference is between the shortest and tallest, as measured on the sight itself?

Thanks

[W.E.G.]

Does anybody have the data on the nominal difference in height between the different posts. How much differnce does one dot make?

[Mr pogo]

Ive seen Israelis numbered from 2 thru 6, this is not inclusive so there might be lower and higher numbers made.
Measuring the Izzies, aproximately .0185" difference between each number, higher number = taller sight post.

[Falcon]

A while ago,I measured a 1 and 2 dot from STG's and the difference was .020" between them.IIRC,the 1 dot was .140" tall, from the base and the 2 dot was .160" I would assume a 3 dot is .180", etc.

[Derby FALs]

If you can't bring it up enough withthe front sight you might try an Inch rear site. I used one of the folding ones on mine to bring the POI up and still have enough front post showing to get a good sight picture.

[EMDII]

Originally posted by gary.jeter:
Does anybody have the data on the nominal difference in height between the different posts. How much differnce does one dot make?

IIRC, the ehights vary by 0,5 mm between each variant for the metrics and the Inch.

FWIW:
the overall Inch heights are as follows-
Number 4 10.17 mm
Number 3 9.67 mm
Number 2 9.17 mm
Number 1 8.67 mm
Number 0 8.17 mm
Unmarked 7.67 mm
Unmarked 7.17 mm

Metrics:
(measured from bottom of threaded post to top of pin, and top of pin to bottom of base)

2-dot Model C: 15.2 mm overall
(used on G-1 and most subsequent metrics)
6.5 mm 'post height' (including base)

'1' Model A: 16.6 mm overall
(used on earlier high sightline metrics, such as Israeli and Argentine)
9 mm 'post height' (including base)

FWIW: the FN-measured height only inlcudes the base thickness and pin height (it is the smaller of the two heights above). If you go through the mental gymnastics of the conversion to the G-1' sightplane (which is 3 mm lower than the earlier FAL-Canada versions) the Type B '1' has an equivalent post height of 6 mm.

I know the Inch measurements. I had to extract the Metrics doing the math above. So, my extrapolation (read 'yank') is:

Unmarked- 5.5 mm
1- 6.0 mm
2- 6.5 mm
3- 7.0 mm
4- 7.5 mm

Someone pull a Type C (G-1, StG, etc) foresight pin numbered 3-dot or 4-dot and square me away.

[kotengu]

Good info, Ted - but isn't it illegal to post inch front sight measurements in millimeters?

[EMDII]

Originally posted by kotengu:
Good info, Ted - but isn't it illegal to post inch front sight measurements in millimeters?

Interestingly, that is how the British measured them. FWIW- this is how Blake Stevens reports them, as 'excerpted' (not transposed) from the 1954 report by 'The Inspectorate of Armaments, Woolwich Aresenal' in a report entitled "Notes on Rifle, 7,62 mm, X8E1 (known as FN Type A0 and X8E2 (known as FN Type B)for Troop Trials; Land Service 1954".

The differentiation between Metric and Inch patterns is not so much the actual system of measurements, but rather in the pertinent 'owners': ABC- (Australian British Canadian, and their client states) for the L1A1 series, and the rest of the world for the so-called 'Metric' series. There never was an official 'Inch-pattern' or 'Metric-pattern' at FN.

The OFFICIAL "Inch-pattern" drawings were maintained by Canada. All other Inch-pattern rifles were derivative from Canadian. FN first sold rifles to other countries using the "FAL-Canada" model! The so-called Metric did not exist until the Germans demanded concessions on the manufacturing of the G-1. The changes were so dramatic as to prompt the use of the phrase "Metric pattern".

The Devil is in the details!
1* to risk in Metric is still 1* in Inch!

[ September 04, 2001: Message edited by: EMDII ]

[EMDII]

Copying to FAQ

[Jen]

What difference does each sight post make in the POI at 100M or 100Y? Is there a formula for determining what sight post is needed based on how far off your POI is at a specified range and what sight post or sight height you already have?

[EMDII]

Well, the POI moves 1cm per click at 100m. So what. that doesn't help.

Reach for the slide rule! How many of you are old enough to remember a slide rule!?

If I did the math-trig right, (22" sight radius, yadayada, voodoo incantation), then a 0.5mm change in elevation (or sight tip height) moves the pip 88.6mm at 100m ,or 8.8cm, or 3.48".

So changing one 'dot' or foresight blade size moves POI about (about) 3.5 inches either way.

One full rotation of the foresight pin on a Metric is 20 clicks (IIRC- don't have the system handy), that's 20cm at 100m, so that means 7.8" +/- at 100m. So, there's plenty of overlap to go from one pin height to the next.

[Monk4064]

How many MOA is one full revolution on the inch front sight?

[Sean]

Here's some infor from another post for ya!

SeanFAL Files

[EMDII]

1 complete revolution of the foresight blade moves MPI 8" at 100 yards. Ergo, about 7.95 MOA.

[W.E.G.]

The way I figure it, each click on the front sight is worth about one centimeter at 100 meters.

Here we go.

You gotta move the sight .006" to achieve one minute-of-angle change (or one inch at 100 yards).
See http://www.falfiles.com/forums/showt...threadid=21880

The metric front sight post is threaded 28 TPI
See http://www.falfiles.com/forums/showt...ighlight=pitch

So, for the metric you got .036" movement per revolution (6 minutes, therefore 6 inches at 100 yards.)

I'm looking at an IMBEL front post. The underside has 16 ridges. So, 16 ridges per revolution means that each ridge ("click") moves the sight 0.00225" (we'll say .002 for convenience). Therefore, one click equals 1/3 minute...which means 1/3 of an inch at 100 yards.

Y'all check my math now.

[W.E.G.]

Originally posted by Conagher at http://www.falfiles.com/forums/showt...hreadid=141055
I hate to revive an old thread, but I still need a 4 dot belgian style front sight post for my FAL.

I called Sarco and talked to Spencer, and he said that all of his Belgian front sights have 0-5-10-15 on them but no dots.

I just called DSArms and asked the sales gal what the differences between their #1 thru #4 Belgian style front sights. She said that this is the difference:

#1 - the post heighth is .143
#2 - the post heighth is .169
#3 - the post heighth is .194
#4 - the post heighth is .220

Then I asked her if their front sights have dots on them and she said that they did. I asked if #4 was a 4 dot sight, and she said that it was in fact a 4 dot sight.

I just thought I'd help other members here on the forum when they are in the same situation that I'm in.

[preston1026]

If it is possible I woulld really like to see a sticky with a table. Showing something like

Barrel Length. Point of aim at 25 meters distance for Zero @200m also 100m
16"
17"
18"
21"

also include para zero'ing since the flip sight is 150 and 250 instead of 200.

I am no expert at all so if there are other varitables like bullet weight or even if the barrel length comes into play at 200 meters.

Seems like sighting in / zero'ing comes up a lot