Are CZs especially hard on Red Dot Sights?

[Atomic Punk]

I have an SP-01 Tactical as a competition gun and a PCR as my carry gun. Both were milled for the Holosun 507K by CZ Custom.

The 507K matches the width of the slide nicely and the built-in rear sight lines up perfectly with the factory front sight. The back up irons are unobtrusive in the small window but work when needed.

I am happy with this set up with one big exception. The Holosuns keep breaking. I shoot about 1000 rounds a month between the 2 guns, and in the last 2.5 years, I've been through FIVE sights. The + button stopped working on 2, the glass cracked on one, and the head of the battery tray screw has sheared off twice. Holosun replaces them for free but I'd obviously prefer they not break. Replacing, shipping and re-zeroing is a pain.

The vast majority of gun people say Holosuns are great. Are they overrated or are CZ-75 pistols just especially hard on Red Dot Sights in general?

Edit: I use factory ammo of 130-135 PF (mostly 124 Blazer Brass and Magtech) and run a CGW green recoil spring in both

[M1A4ME]

Zero issues with the Holosuns on my .40 S&W P07 and it runs some butt kicking reloads.  Like 4" .357 magnum revolver recoil levels and concussion that makes you think it's a magnum as well.  The Holosun has only been on it about 2 years now since Trijicon failed to repair a couple RMRs I sent back to them (not for breakage but for the tritium sources finally getting to weak to be useful in low light conditions.

[Joe L]

I only have one 507K and it is on a polymer gun and has been fine. 

One thing you might consider checking on the SP-01 with the green spring.  If it is ejecting brass say, 15 feet out, perhaps the slide impact is higher than usual in recoil, and this may contribute to the sight failures?  I know in run and gun, once you find a spring rate that is best for followup shots, you are hesitant to change, but perhaps go 2 lbs higher in recoil spring rate and see if that helps? 

I tend to run as heavy a recoil spring as will allow the gun to cycle for lock up consistency for long range shooting at a very slow pace but I haven't had any problems with the Holosun sights on three polymer guns.  I have Burris ff3 on the steel guns in a dovetail mount and no problems there either.  The steel guns "feel" more violent in recoil than the polymer guns even with factory springs so maybe a steel gun with a light recoil spring would be the worst combination for the sight.  Just a thought. 

Joe

[tdogg]

There are a lot of Carry Optic and Limited Optic CZ guns out there and the Holosun is on many of them.  I chose the Trijicon SRO for reliability as I've seen a fair number of dot stop working in competition (working as an RO).  I only have one year in Carry Optics so I can't say much with respect to long term durability on my Accushadow 2 yet.

Looking at last years Nationals equipment survey 4% of folks use Holosun as an optic in Carry Optics.  That number jumps up to 34% for PCC.  Folks are using them but not sure how often they are replaced?

Trijicon and Sig top the usage in Carry Optics and there is a reason for that, durability.  I was at nationals a number of years ago and ran into another shooter at dinner the night before.  Turns out he was in law enforcement and his department was piloting carry optics for duty.  They chose the Trijicon optic as they had tested putting them through a ton of rounds (north of 50k) and they all still worked without issue.  It was the best sales pitch that wasn't a sales pitch I've ever had.  When I went to build my Carry Optic rig last fall, I chose Trijicon for that very reason.

Cheers,
Toby

[Atomic Punk]

I only have one 507K and it is on a polymer gun and has been fine. 

One thing you might consider checking on the SP-01 with the green spring.  If it is ejecting brass say, 15 feet out, perhaps the slide impact is higher than usual in recoil, and this may contribute to the sight failures?  I know in run and gun, once you find a spring rate that is best for followup shots, you are hesitant to change, but perhaps go 2 lbs higher in recoil spring rate and see if that helps? 

I tend to run as heavy a recoil spring as will allow the gun to cycle for lock up consistency for long range shooting at a very slow pace but I haven't had any problems with the Holosun sights on three polymer guns.  I have Burris ff3 on the steel guns in a dovetail mount and no problems there either.  The steel guns "feel" more violent in recoil than the polymer guns even with factory springs so maybe a steel gun with a light recoil spring would be the worst combination for the sight.  Just a thought. 

Joe

I thought that may be an issue, that's why I added that info to the OP.

The gun came from CGW with the red recoil spring. After the 2nd dot died, I upped it to the green. Maybe, I need to go even stronger.

[tdogg]

Is your dot direct milled or does it have a plate?  Is it pinned or does it rely on the screws only?  Any movement could be imparting a lot of force on the optic.  I mounted my optic with CZ customs RDS plate system so I could swap back to irons if desired.  It's held tight thus far.

I can't imagine a 13lb recoil spring being the problem.  Most folks run lighter.  Since your running factory loads the 13lb is probably the right spring.

Cheers,
Toby

[Joe L]

I can't imagine a 13lb recoil spring being the problem.  Most folks run lighter.  Since your running factory loads the 13lb is probably the right spring.

Cheers,
Toby

In spite of what I said in the message above, I agree with Toby, 13 lb should be ok.  15 lb is definitely OK.  I will be silent now and try to back out gracefully...

Joe

[Atomic Punk]

Is your dot direct milled or does it have a plate?  Is it pinned or does it rely on the screws only?  Any movement could be imparting a lot of force on the optic.  I mounted my optic with CZ customs RDS plate system so I could swap back to irons if desired.  It's held tight thus far.

I can't imagine a 13lb recoil spring being the problem.  Most folks run lighter.  Since your running factory loads the 13lb is probably the right spring.

Cheers,
Toby

It is direct milled with no plate. The sight is held on with the screws only but the pocket is very tight. It takes some effort to get it in just the right position to drop into the pocket. As a result, there is zero front to back movement of the sight on the slide.

I also used blue loctite, torqued the mounting screws to 18 inch/lbs and witness marked the mounting screws so I know it was not loose.

[tdogg]

I got nothing.  It sounds like you just might be unlucky?

The CZ platform is very popular and a lot of them have dot's on them including the Holosun's.  I don't know why you have killed so many???

Cheers,
Toby

[Thauglor]

It could be that since it is so tight in the milled area, the forces are being transferred to the frame ends instead of the screw/pin locations where it was designed to be transmitted through.  This causes different harmonics and different internal forcing/bending that could be leading to failures

[Atomic Punk]

It could be that since it is so tight in the milled area, the forces are being transferred to the frame ends instead of the screw/pin locations where it was designed to be transmitted through.  This causes different harmonics and different internal forcing/bending that could be leading to failures

That's a pretty good hypothesis.

Unfortunately, I can't think of any way to test it, or remedy the issue if that is it.

[RSR]

It could be that since it is so tight in the milled area, the forces are being transferred to the frame ends instead of the screw/pin locations where it was designed to be transmitted through.  This causes different harmonics and different internal forcing/bending that could be leading to failures

That's a pretty good hypothesis.

Unfortunately, I can't think of any way to test it, or remedy the issue if that is it.

Have whoever you had do the milling take an add'l mil or two off of the front and rear of the pocket...

[Thauglor]

Have whoever you had do the milling take an add'l mil or two off of the front and rear of the pocket...

Yep, that is the only way unless you want to break out your own files and do the work yourself, but I would use a milling machine only for this.

That is some good customer service from Holosun, it is obviously this pistol/users issue, not theirs.  I would have stopped at 2 replacements if it was my company

[Wobbly]

Yep, that is the only way unless you want to break out your own files and do the work yourself, but I would use a milling machine only for this.

That is some good customer service from Holosun, it is obviously this pistol/users issue, not theirs.  I would have stopped at 2 replacements if it was my company

That's just silly.

"One thou" is 1/3 to 1/4 the diameter of a human hair. A very, very, very small amount of material. Heck, just removing the paint/ cerakote (Sp?) coating under the optic would get you 0.004" at each end !! That's 0.008" total.

Removing half the paint thickness at both ends of the relief, using very small, sharp files will give you the 0.004" you seek.

[Atomic Punk]

It could be that since it is so tight in the milled area, the forces are being transferred to the frame ends instead of the screw/pin locations where it was designed to be transmitted through.  This causes different harmonics and different internal forcing/bending that could be leading to failures

That's a pretty good hypothesis.

Unfortunately, I can't think of any way to test it, or remedy the issue if that is it.

Have whoever you had do the milling take an add'l mil or two off of the front and rear of the pocket...

I will give this a try. A stroke or 2 w/ a fine file should do the trick.

I do worry that will put all the stress on the mounting screws but I need to do something.