Author Topic: CZ 2075 RAMI BD Sight Alignment Solution  (Read 7672 times)

Offline PappaWheelie

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CZ 2075 RAMI BD Sight Alignment Solution
« on: June 23, 2016, 09:14:32 PM »
     I’ve become convinced that the CZ 2075 RAMI BD is absolutely without peer in the marketplace.  It’s a subcompact (having 3” barrel concealability), but offering the unmatched, no-compromise ergonomics of a full sized CZ-style forward-hooking grip with its 14+1 capacity extended magazine.  Those attributes (3” barrel and 15 round capacity) alone put it in a class by itself, even before beginning to tally its unmatched other advantages, which to me rank something like:
1.) DA/SA “real gun” functionality with foolproof decocker safety that can’t be accidentally forgotten under stress.
2.) 27mm slide width, 28mm frame width, 32mm grip width concealability advantages, and Best of the Best CZ “ergonomics,” (“big boy” trigger reach and full fingered grip of extended magazine).
3.) 7075 T6 Investment Cast Alloy Frame: very soft shooter, with internal rail architecture’s legendary accuracy benefits (and no-brainer manufacturing cost/value to the customer advantages!); also provides strong thumb registry area between slide release and decocker lever.
4.) CZ-legendary reliability: optimized slide mass, dual-series recoil spring travel magnitude/stiffness, and generous, factory-polished, gentle feed ramp combine with optimized magazine/chamber/breech face/extraction lever details to handle all ammos.

5.) TruDot Tritium night sights standard; generous 5” sight radius enables “big gun” aiming ease.

Etc., etc., however; the subject of this blog is to highlight an issue that caused me several weeks worth of a problem with my RAMI’s sight alignment; hopefully the cut-to-the-chase of what I’ve learned will benefit others.

My front sight is staked in a just perceptibly right-of-center location, and I’ve not wanted to incur the cosmetic penalty of deranging that interface as staked.  Numerous target practice patterns all testified, in agreement with the factory-supplied QC test pattern document, to a leftward bias in as-received sight alignment.

Several rear sight adjustments, just shy of calculated value initially, and then fully to calculated value later on, kept producing patterns with left bias, although first shots after adjustment were always quite well centered.
I was using dial calipers to measure from the RH edge of the sight to a machinists parallel clamped to the RH face of the slide for consistently accurate sight location assessment.  I finally realized that the sight was not holding its adjusted location but reverting, over the course of one extended magazine’s recoil shocks, back to its pre-adjustment location.

Application of Anti-Sieze compound to the threads of the sight-fixing setscrew helped stabilize the adjustment, but it was still migrating over the course of three extended magazines worth of ammo.  I finally removed the sight entirely, in preparation for cleaning and “cementing” it in place with Loctite, only then seeing the root cause of my wandering rear sight.  Centered under the sight was a 2.5mm diameter, 1mm deep drilled hole, its RH edge burnished by having the sight-fixing setscrew tightened in the off-center location that my pistol requires for pattern centering.  The shocks of recoil-action contact between the slide’s spring boss and the frame were sufficient to dislodge the (flat bottomed) setscrew from its precarious perch at the edge of the hole, sucking it into the (literally) black hole and thus re-centering the sight to its original, off-center-shooting location.

The remedies for this unfortunate design feature were to either fill it to create a flush slide-top surface at the bottom of the sight dovetail, or mill an enlarged flat at or below the depth of the drill point.  I took the quicker and easier, in the circumstance, option of the former, by carefully hacksawing off the tip of a #40 (~2.5mm) twist drill’s shank, cementing it in place with J-B Weld, and then after curing, carefully dressing it down to flush with the surrounding surface with a fine Swiss Pattern half round file.

Remounting the sight, and tightening the setscrew with the sight at the target location, represented the end of my woes.  The sight has finally stayed put, and my patterns are commensurately tighter, no longer being inclusive of the migration of my rear sight over the course of the three magazines that I typically shoot.

I have submitted a letter to CZUB, via CZ-USA, suggesting the deletion of this drilled hole feature, as well as abandoning the firing pin sticking-prone coiled-type firing pin retaining pin in favor of a CGW-proven spring-type firing pin retaining pin which, by the way, would allow visual detection of deformation, if present, by virtue of its hollow center, long before actual firing pin sticking commenced.  I included a picture of my original firing pin retaining pin, with its halfway-through notch.

I also, as a bonus suggestion, provided an image of the original photographically clear broach mark in my RAMI BD’s hammer SA tooth face, suggesting appropriately more diligent tool change controls as potentially beneficial to marketing and promulgation of the enviable mystique of the CZ marque.

The bad news is that CZUB currently sells everything they can build, and likely will for the forseeable future, as “perilous times” continue to encroach, so they may not be highly motivated to implement such changes for the sake of future customers.
 
« Last Edit: October 27, 2018, 08:12:30 PM by PappaWheelie »
Member, Gun Owners of America
CC: CZ 2075 RAMI BD in PappaWheelie Invisible 15 Round RAMI Holster
Homeboy: CZ 97 BD, Underwood 45 Super 120 Grain Xtreme Defender ammo
UBG: CZ 75 SP-01 Tactical Urban Grey Suppressor-ready
-all w/ CGW Short Reset Kit/1485-T2 Disco, 5 "Thick" Trigger, polished SA tooth

Offline PappaWheelie

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Re: CZ 2075 RAMI BD Sight Alignment Solution
« Reply #1 on: April 12, 2018, 01:07:33 PM »
Yesterday I did a four targets, four magazines sight alignment check using my homebuilt post-mounted steady rest, having actually measured the distance to target this time with my 100' tape measure, and concluded that a further fine-tune of my RAMI's rear sight would be worthwhile.

I thought it might be of benefit to some, at least, to document the method I use for measuring the lateral location of the rear sight, as well as to take a picture of the plugged sight setscrew-capturing hole while the sight was removed.

Of additional potential benefit to some, I hereby discuss the "how-to" of arriving at the magnitude of a desired sight adjustment, and while I'm at it, document for the record that the RAMI's barrel length is not 3" (or 3.05" as advertised by CZ-USA). The measured barrel length, from rear face of chamber to front face of barrel, is 2.930" -almost 2mm shy of the 3" "Subcompact" designation. No wonder it's so concealable!
http://www.czforum.com/forum/index.php?topic=5480.0

Sight Adjustment Formula
Define:
D=distance to target in inches (=yards*36 or feet*12);
C=correction (at target plane) necessary to center group, inches;
R=sight radius (back of rear sight to back of front sight), inches;
A=sight adjustment magnitude, inches;
https://drive.google.com/open?id=1F0MfknTphQx8Sr8oCNgBnRvO3YB8Mdfh Diagram
For similar right triangles (same angle), the ratio between adjacent sides remains constant, i.e., C/D=A/R
To solve for adjustment magnitude A, multiply both sides of the equation by the same factor, namely R, so that R/R cancels to unity leaving A alone; A=R*C/D

I refinished the plugged setscrew hole a bit because the prior setscrew left a Brinell mark that would act to destabilize the newer location. Here's a cellphone through loupe closeup:
https://drive.google.com/open?id=1UFainWFddjrG31Y6p5GHfW40C22ebIIk

The sight's lateral location is repeatably measurable with dial calipers from a slide side face reference plane as established by a machinist's parallel C-clamped (using a cardboard pad to protect slide finish from C-clamp) flat against said slide side face.
https://drive.google.com/file/d/1bJuJStBuiDdJQFGmqKfQvay1X4150wdZ/view?usp=sharing

The sight adjustment amount A is added (keeping common direction convention) to the pre-adjustment lateral location measurement to get a new target lateral location measurement. In the present case the new target location dimension turned out to be 0.178" which left the sight more centered visually than my prior "fine tuning" effort.

One last bit worth sharing: the sight setscrew is pretty tiny, with a 1.5mm hex socket. My Bondhus 1.5mm Allen wrench fit the setscrew with a bit more slop than I liked, which left me wondering if perhaps the slightly larger (1.5875mm) nominal size of a 1/16" Allen wrench might work. It worked splendidly, fitting snugly enough to require diligent wiggling to get to full depth engagement and then exhibiting zero slop, enabling full tightening with confidence vs. any risk of stripping flats.
« Last Edit: April 12, 2018, 01:23:06 PM by PappaWheelie »
Member, Gun Owners of America
CC: CZ 2075 RAMI BD in PappaWheelie Invisible 15 Round RAMI Holster
Homeboy: CZ 97 BD, Underwood 45 Super 120 Grain Xtreme Defender ammo
UBG: CZ 75 SP-01 Tactical Urban Grey Suppressor-ready
-all w/ CGW Short Reset Kit/1485-T2 Disco, 5 "Thick" Trigger, polished SA tooth

Offline PappaWheelie

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Re: CZ 2075 RAMI BD Sight Alignment Solution
« Reply #2 on: April 19, 2018, 08:51:50 PM »
After a second outing shooting a magazine per target, I've settled on a 0.171" slide face to sight edge dimension as best for my RAMI BD.
Member, Gun Owners of America
CC: CZ 2075 RAMI BD in PappaWheelie Invisible 15 Round RAMI Holster
Homeboy: CZ 97 BD, Underwood 45 Super 120 Grain Xtreme Defender ammo
UBG: CZ 75 SP-01 Tactical Urban Grey Suppressor-ready
-all w/ CGW Short Reset Kit/1485-T2 Disco, 5 "Thick" Trigger, polished SA tooth

Offline PappaWheelie

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Re: CZ 2075 RAMI BD Sight Alignment Solution
« Reply #3 on: May 01, 2018, 12:12:50 PM »
Finally got a chance to check out the 0.171" sight location dimension, which I pre-sealed with Loctite in anticipation of its correctness: 24.5 yds = 22.4 meters


https://drive.google.com/open?id=1wMjPmHwluE2_Z_FISP4i7mz45tJyg3vc


https://drive.google.com/open?id=1xIoOK2H8cUWVyFArnfHBW36Gs8k3ZREv


I think I'm finally there.

« Last Edit: May 01, 2018, 04:43:36 PM by PappaWheelie »
Member, Gun Owners of America
CC: CZ 2075 RAMI BD in PappaWheelie Invisible 15 Round RAMI Holster
Homeboy: CZ 97 BD, Underwood 45 Super 120 Grain Xtreme Defender ammo
UBG: CZ 75 SP-01 Tactical Urban Grey Suppressor-ready
-all w/ CGW Short Reset Kit/1485-T2 Disco, 5 "Thick" Trigger, polished SA tooth