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View Full Version : SUIT: cam dimensions (5.56 & 7.62 mm NATO)


EMDII
December 29, 2001, 13:08
Especially for you folks getting Israeli SUITs w/o any markings. Measured diametrically across the flats

7.62x51mm NATO cam-
11.6 mm (0.4567")
11.9 mm (0.4685")

5.56x45 NATO cam-
11.7 mm (0.4606")
11.9 mm (0.4685")

I made these measurements on the LH end-cam, as the right has the selector lever and is not truely diametric there.

FWIW- Israeli (and UK-made) 5.56x45 mm data plates will have 250m and 450m ranges for selection, and L2A2 7.62x51 mm NATO SUIT data plates will have 300m & 500m respectively.

(Corrected the 250/450 typo 12-31-01)

[ December 31, 2001: Message edited by: EMDII ]

Dennis
December 31, 2001, 17:19
Thanks for the info, and I would suggest that everyone (like me) who has purchased "refurbished Izzy FAL SUITs" without any range indications marked on the label double check the dia on the cams.

Falfegnügen
January 01, 2002, 13:23
Ok, I've dissassembled and carefully measured the cams on 3 different SUITs, using both a dial caliper and a vernier caliper.

#1 Israeli Marked 250mem and 450mem

0.4570"
0.4668"

#2 L2A2 1240-99-964-7647 No range markings

0.4590"
0.4675"

# Israeli - missing ID plate

0.4550"
0.4625"


It appears to me that comparing actual dimensions between cams is probably meaningless. After looking at several more (without dissasembling the cam to measure) it appears that there are very noticable differences between the cams, with little coorelation to what the ID plate says.

So I suppose it's the relative difference betweent the two measurements of the cam that truly matters. Still, the results don't seem very conclusive. So I ask:

How much difference in velocity is there between 5.56 and 7.63 anyway?

Maybe there are not really two difference cams?

Anyway, now I'm really confused and my wife is yelling at me to get off the dang computer.

Happy New Year!

[ January 05, 2002: Message edited by: scottgs ]

EMDII
January 01, 2002, 17:33
It may be reverse engineered!
VOILA!

Take a 5.56x45 mm and shoot it from your Kosher M16. Derive the points of range at which the bullet crosses the LOS. VOILA, 250 and 450 M!

It's so obvious. The Israelis are too cunning to waste time. 'SGT! Go out there and see where it hits!' says the CO of the ordnance school! SGT Shclomo wanders out, buggers it all onto paper, and comes back and reports 'General- My properly zeroed M16, to which I have affixed this sight, hits targets at 250m when selected aft, and 450m when selected forward!' End of R&D project, print a bunch of sticky data plates, rip off the old one, stick on the new, and VOILA!

Could it be that simple?

Buddie @ www.tapco.com
January 01, 2002, 18:48
We too found that the dimensions on the cams varied.

It seems that some of the Izzy surplus units were modified to the 5.56mm and others were not. Some of the Brit surplus units were even sporting the 5.56 cams.

This study sent us to find reliable New SUITS that still had the correct cams. After lots of money and study and more money, we came up with the correct dimensions.

We have had several requests to release our findings. To this I respond..

All of the findings are not something that we will publish. We invested a great deal of time and money to produce correct cams for the SUITS, and we wish to sell them. Nothing more or less, just looking for a return on our investment.

EMDII
January 01, 2002, 19:16
Sounds good to me!

Not owning a pristine 5.56 cam, I'll stand on my findings. They are different, if only in thousandths. The ballistics are sufficiently strong that a thou here or ther makes a POI shift.

FWIW-
M855 5.56 ball (SS109) has a MV of 3025 fps.
M80 7.62 ball has a MV of 2750 fps.

Ballistically, they perform this way:
7.62x51 mm 450 range drop:
58 inches

5.56x45 mm 450m drop
52 inches

This, even though the BC for 5.56 is .24, and the BC for 7.62 is .38. Just shows that GRAVITY is in control. BC has more to do w/ external ballistics in a constant gravitational field (ergo, wind), than it does w/ much else.

MarkG
November 26, 2005, 03:57
We invested a great deal of time and money to produce correct cams for the SUITS, and we wish to sell them When will you have those in stock?

brownknees
November 26, 2005, 06:09
This got me curious enough to run the 7.62 & 5.56 rounds, with the listed MV thru an external ballistics program.
That in turn led me to start playing "what if?" games.
Let's suppose that for some reason I don't want to use the 250/450 as the range settings.
In thoery I could sight in at the close range setting; We'll call it 100 Yds, just for kicks & giggles.
I could then zero at that range, swithch the cam position & have a different (closer) long range setting also. I could verify this by shooting at the estimated new long range setting, and if needed re-shooting at a corrected long range based on the second set of POI until I had a good long range zero distance.
Essentialy I'd be re-calculating the 2 points of convergance. By modifying the trajectory path's line to a differently angled optical path.
Anyone see a glitch here?
Equally I could switch the 7.62 cam for the 5.56 cam & do the same thing, but with different short/long range zeros, I could then "tweak" this by changing the short range zero & then re calculating the long range zero also.
Taking this a step further I could also recalculate for a different bullet weight by the same means, no?
BTW. Is a kosher 16 one that is
a: more than 16 years old &
B: had the muzzle threads removed?
:eek:

brownknees
November 27, 2005, 07:01
Following up on what I was rabbiting on about earlier I had the clever? idea of measuring, not the cam dimensions, but the change in angle of the SUIT itself.
The idea was to pick 2 datum points, one on the reciever, one on the optics tube. Then measure the distance between these 2 points with a good digital caliper.
Then switch the cam position & remeasure the same distance.
Once that was done then it's simple math to calculate out the change in angle & apply that to the LOS/LOF & calc out the actual change.
However, I'm darned if I can find a good datum point to do this that's a: the same on different recievers, & B: where you can get the jaws of the caliper into position to take an accurate measurement.
Any suggestions?