Q&A for ZCO 4-20x50mm Field Eval

[caberslash]

It has Tier One rings which is the company that makes Zeiss rings so I can't say categorically it's not the rings.

It's probably the rings, Tier One are not a good design, can say this from experience. Think Form noted the same in the LRP review.

 

[4th_point]

I've just come back from a 2 week trip. Rifle rode in 4x4 on back seat with other rifles and equipment so nothing too wild but it's not babied. Standard stuff. My ZCO had a 1mil zero shift half way through. I'm coming from an ATACR on the same setup and no change in zero over 7 years. It has Tier One rings which is the company that makes Zeiss rings so I can't say categorically it's not the rings.

That sucks, but thanks for sharing.

Was the ATAC-R in Tier One rings?

Jason

 

[ZAR EC]

That sucks, but thanks for sharing.

Was the ATAC-R in Tier One rings?

Jason

ATACR was in Nightforce ultralights.

 

[4th_point]

I'm curious if the ZCO/ring configuration just shifted in elevation, or in combination with windage?

 

[ZAR EC]

I'm curious if the ZCO/ring configuration just shifted in elevation, or in combination with windage?

Just elevation. There is no obvious scope or ring movement. Everything is locktighted and correctly torqued. No screws have come loose. Rail is bedded.

 

[ZAR EC]

Some testing that has nothing to do with durability, but may be of interest. Shooting at extended ranges in very bad/low light is standard practice therefore low light ability is a major factor in selecting optics after durability for me. I compared my ZCO4-20x50, Minox zp5 5-25x56 and S&B PMII Ultrashort 3-20×50 for low light capability until pitch black. The clear winner by a good margin was the Ultrashort which is surprising given the 50mm objective. The ZP5 5-25 very marginally outperformed the ZCO which isn't too surprising given the 56 vs 50mm.

 

[4th_point]

Interesting observation on the low light performance.

I don't know about the two other scopes but the ZCO is short and I think it was a big deal when it first came out because of it. From what I understand, that short design requires more lenses and wonder if that explains the difference in brightness.

Anyway, have you looked into the zero shift more? Any chance it was ammo related or due to the rifle?

Not to rub salt into it, but the dealer I was going to use for a ZCO 420 stopped using them on hunting rifles. He's seen ZCO issues on his personal and customer rifles. They went back to ATAC-R but still sells ZCO. I'd buy the ATAC-R but don't care for any of the reticles.

 

[ZAR EC]

I will be able to check in a few weeks and eliminate all possibilities.

The S&B PMII Ultrashorts were the original "Ultrashort" concept and (I think) designed for short military rifles that needed front mounted NV. Generally I'm not a fan of the concept. There is zero practical advantage for me by having a scope squished 2 inches shorter but there are several disadvantages. The ZCO 5-27x56 is a much nicer scope in every aspect compared to the 4-20 yet once mounted on the rifle the footprint is not that different between the 2. If neither hold zero then that is a moot point....

NF reticles are not great but I've found that the ones that have 0.04 mil stadia to be quite visible for me from around 6x power and similar to the ZCO MPCT1 and MPCT2.

The best low light reticle I've used is the S&B P3. I have an ex UK military S&B PMII 4-16x50 with that reticle and it's the best low light long range scope I've ever used. It was made in the early 2000's and optically it's better than anything I've seen in low light. It has 0.06mil stadia and very thick outer bars.

 

[zr600]

It sucks, because the ZCO is magical to
Look through haha. But that just isn’t what matters the most. My 527 also had oil splash onto the lense while shooting. So there was like 4 oil droplets in the view all the time. After the Parralax issue and then the oil drops, I just couldn’t do it man. No regrets on the ATACR, but low end magnification sucks. Tunnels a lot until you get up to around 7X

Was the oil drops on the lens from lube inside the scope?

 

[huntnful]

Was the oil drops on the lens from lube inside the scope?

I’m assuming so. They are definitely inside the optic

 

[ZAR EC]

I will be able to check in a few weeks and eliminate all possibilities.

The S&B PMII Ultrashorts were the original "Ultrashort" concept and (I think) designed for short military rifles that needed front mounted NV. Generally I'm not a fan of the concept. There is zero practical advantage for me by having a scope squished 2 inches shorter but there are several disadvantages. The ZCO 5-27x56 is a much nicer scope in every aspect compared to the 4-20 yet once mounted on the rifle the footprint is not that different between the 2. If neither hold zero then that is a moot point....

NF reticles are not great but I've found that the ones that have 0.04 mil stadia to be quite visible for me from around 6x power and similar to the ZCO MPCT1 and MPCT2.

The best low light reticle I've used is the S&B P3. I have an ex UK military S&B PMII 4-16x50 with that reticle and it's the best low light long range scope I've ever used. It was made in the early 2000's and optically it's better than anything I've seen in low light. It has 0.06mil stadia and very thick outer barbars

Update on this. I gave the rifle a full overview. No screws loose and no (obvious) movement of scope in rings. Rifle still groups as well as ever and poi remains same across 2 separate reloads of ammo so no issues there.

The scope is bedded in rings and rail is permanently bedded to receiver. Action is torqued to 60 and very tightly bedded with steel pillars within full carbon stock.

ZCO's have taken a back seat for now until more info is available. I have some alternative Recknagel/ERA rings available and may switch and perform some drop tests and see how things go.

Anymore info from Form on how the tested ZCO is performing would be much appreciated

As a side note, during testing I had my first Tikka failure. Snapped the bolt stop pin. Nothing serious but worth mentioning.

 

[4th_point]

As a side note, during testing I had my first Tikka failure. Snapped the bolt stop pin. Nothing serious but worth mentioning.

Awesome, thanks for the updates.

Bolt stop pin failures don't seem super common with that design, but obviously it could be improved. Thanks for sharing.

 

[Mathews2000]

Any updates on this thread?

Has anyone had issues with the 5-27 versions?