ZCO 4-20x50mm Field Evaluation

[Formidilosus]

This will be a field evaluation of the Zero Compromise Optic 4-20x50mm with MPCT 1 reticle. This scope was purchased by Ryan for this evaluation. The ammunition used was Hornady Black 155gr AMAX personably purchased by Ryan. 2x10 round groups with it at 100 yards were 1.3 and 1.4 inch.


The scope and weight-



Turrets:

Both elevation and windage are locking pull-up/push down type. Elevation has a zero stop and rotation indicator button with 15 mils per rev; windage is rotation limited each direction to 7.2 mils.

This is the up/unlocked position-



MPCT1 reticle:

The MPCT1 reticle is a standard .2mil per tick, non tree reticle. 8 mils from center on windage and 12 o’clock. It is better in visibility on low power than most.


4x


20x



Illuminated:

4x



20x



The illumination is infinitely variable (no clicks), and has a “night” setting that is very low power.




Con’t…

 

[Formidilosus]

For this eval @Ryan Avery and Jake from @Unknown Munitions helped/participated, along with 3 others.



Zeroing:


Scope was mounted using ZCO rings and exactly as the ring manual stated. 35in-lbs on base screws, 20in-lbs on ring caps. The ring caps screw are larger than most common ring cap screws (which means they need a higher torque spec to reach the same clamping force), and I commented that the scope wasn’t going to hold. Also the single smaller base clamp screw didn’t inspire confidence.



Boresighted and fired 10 rounds at center dot (labeled “BS” and “1”). Rounds hit low and right. Group was larger than any fired with this rifle and ammo in the last two days (5-6x 10 round groups). Used reticle to read the correction, adjusted fired another 10 round group at top left dot (#2). Again, not only was the group noticeably larger than normal for this gun, it was strung horizontally. We then let the barrel cool down.
Following, I tried a ten round group from Federal Gold Metal 185gr Juggernauts which average under 1 MOA for ten from this rifle- same larger than usual group strung horizontally (#3). Made a left .2 correction, then went to bottom left dot and fired 3 rounds, which were still right of the dot (#4). Adjusted another left .3 mils, then fired three rounds at bottom right dot (#5) which jumped to the left side of the dot.

At this point I adjusted right .2 mils and went to the drop eval because the scope was not consistent and I had fired 40 rounds and still wasn’t actually zeroed. Before being dropped it was noticed that the scope had slipped about an 1/8th of an inch in the rings.

(Pictures and video forthcoming).

So, went back and tightened the scope ring caps first to 25in-lbs which did not move them at all, then at 30in-lbs which did barley tighten them.

Back to the target board and fired ten round rounds at top right dot (#6) which was now a bit smaller, but vertically strung. Made an adjustment of up .3 mils and right .1 mil, then fired three rounds at the next dot down (#7).





They were in the dot, so off to the drop eval.





Drop Evaluation RTZ and “Tracking”

For an explanation see- Scope Field Eval Explanation and Standards


The “test” consists of three 18” drops on a mat- one left/right/top with a shot to check zero after each drop. Then the exact same thing repeated from 36”. Then three drops on all three sides for nine drops on the last part- 15 drops total. This is not “abuse”. The 18” drops are a joke really. The 36” start showing something. And when a scope make/model consistently goes through the whole thing without losing zero, failures in actual use are almost unheard of.

This one was conducted on loose, soft soil with a EVA mat on top. Ryan did the dropping, and all drops were filmed.


Shots are as marked. #1 was a confirmer before any drops and it hit the center Diamond. The left side 36” drop caused a loss of zero to the left 5-6 inches. The right side 36” (#6) knocked it back to the right, the top 36” (#7) landed to left of #6. The 3x3 36 inch drops caused the zero to come back and shot number 8 hit the Diamond.




This was confirmed on the original center dot-




The scope failed the drop eval. Whether it is the scope or the rings remains to be seen.




RTZ and “Tracking”

Following the drop eval the return to zero check was conducted. There were no issue and it now shot a ten round group that is normal for Thai rifle/ammo-





Checking adjustment (“tracking”) went without issue. Used the reticle to measure the center between the dots at exactly 8 mils. It seemed to adjust .1 mil short, however is less than 2% which is about all that live shooting can show.






Conclusions (for now):

The rings when mounted exactly as stated by the manufacturer failed to hold the scope for a braked 308 win. After tightening the rings caps, it’s seemed to hold. It failed the drop eval. It was not close. However, the drops seemed to have cured the abnormally large groups the scope was producing. The RTZ and adjustments are fine. The next step is to get different rings and re eval the drops.

The scope is mounted and zeroed and we will check zero from riding in the truck until then.

 

[Formidilosus]

Subjective observations:


The locking turrets I like. The reticle is pretty decent, definitely one of the more bold and visible reticles in any of the long range scopes currently offered.


Eyebox:

Nothing really noteworthy either way. Was fine.

Parallax/DOF:

Need more time paying attention to it. Will update.


“Glass”:

This one will probably cause as much heartburn with people as the drop eval…. It’s good. No one present thought it was anything really better than any other top end scope. We had a Minox ZP5, multiple different Nightforce’s, and Trijicon Tenmiles to look through side by side. It is better than the Trijicons, and the NF NX8 4-32x’s, mostly in the very edge clarity- but it isn’t earth shattering. It’s not something anyone noticed while shooting, you have to really look for the difference.
Ryan and I both prefer the Minox ZP5 view- by a lot. That may be due to how large the eyebox and FOV seems with the Minox, however side by side that’s what we would both choose.

I and others will be spending a lot of time with the ZCO unless it doesn’t hold zero at all so this will get updated and/or adjusted.

Q&A for ZCO 4-20x50mm Field Eval

Questions and answers for- https://rokslide.com/forums/threads/zco-4-20x50mm-field-evaluation.324966/

rokslide.com

 

[Formidilosus]

The rifle and scope rode in the backseat for about 200 miles and then was sat in a corner for a week.checked zero today-



An almost .3 mil shift.


Will wait until new rings to continue.

 

[Formidilosus]

Needed a scope for a legit LR rifle.


300 RUM IMP with 34” barrel



100 yard groups were larger than any the rifle has ever produced, however it was trued at 1,308 yards with two different shooters going 5 for 5 on a 30” target.