I experienced an adjustment error with my ERA TAC while attending the K&M comprehensive rifle class (detailed here: https://www.snipershide.com/shootin...ourse-oct-9-12-2021-long.7095901/post-9776817). Upon further troubleshooting, I found that the "5 mil" facet actually adds 7.2 mils of elevation. This was confirmed over 15 rounds, fire 3 shots at 0, adjust to the 5 mil facet and fire 3 shots with the original point of hold, repeated. Once I source more ELDMs I will continue to test the other facets, but I wanted to see if others have had similar experiences. I have taken this rig to 1 mile, though not yet with the ERA TAC base, which was purchased specifically for ELR shooting. I would prefer to get this figured out rather than miss the next 1 mile shoot or spending my ammo trying to find where I am at 1 mile with unknown elevation despite having the base set to the 20 mil facet.
- Thread starter mountainman308
- Start date
All mine work fine. Try this to verify.
Mount your scope very securely on something like this…
Mine is homemade and consist of a double thick plywood base the same size as the concrete bench’s at my range with a vice bolted to it and clamped to the table. Scope mounted on a spare rail. Get creative if you need to. Must be rock solid.
Set up your scope and identify a spot with a 5 mil holdover in your reticle pretty far away…. 1000 yards or more. Then adjust your EraTac and see if your crosshair lands on the same spot.
Not enough detail in your post but it could be cant, bad data in your ballistic solver, not taking into account other variables, etc.
I’ve verified both mine and all my buddies EraTacs this way and they are spot on. Never had an issue.
If you’re ever in the DFW area of Texas I can help you out.
Mount your scope very securely on something like this…
Scope Tools
Scope Tool Scope track testing base. Design for Marc Taylor with Alaska Precision Rifle and Frank Galli with Sniper's Hide to check the scopes ability to track properly and return to zero on a...
www.targetsusa.com
Mine is homemade and consist of a double thick plywood base the same size as the concrete bench’s at my range with a vice bolted to it and clamped to the table. Scope mounted on a spare rail. Get creative if you need to. Must be rock solid.
Set up your scope and identify a spot with a 5 mil holdover in your reticle pretty far away…. 1000 yards or more. Then adjust your EraTac and see if your crosshair lands on the same spot.
Not enough detail in your post but it could be cant, bad data in your ballistic solver, not taking into account other variables, etc.
I’ve verified both mine and all my buddies EraTacs this way and they are spot on. Never had an issue.
If you’re ever in the DFW area of Texas I can help you out.
I used that exact tool when zeroing my scope ahead of the class. The 5 mil facet gave me a true vertical adjustment for what its worth. Granted, I was doing this at 200 yards, not 1000+, but I verified level with a LRA sendit level, so it could be cant, but I think its unlikely. Target was shot at 200, so its possible my ballistic solver was off, but not by that much at such short range. I'll give your method a try and see if that changes anything. I'm on the VA/WVA border so a fair ways from DFW, but I appreciate the offer.
Interesting
I always thought the steps were 10 moa each on the era tac, does appear to be a mil version available.
What was your measured offset at 200 yards?
I always thought the steps were 10 moa each on the era tac, does appear to be a mil version available.
What was your measured offset at 200 yards?
Last edited:
I’m a little confused after re-reading through your first and second post.
Are you assuming your EraTac is off because you didn’t make a hit at a mile?
If so, ya, it’s definitely not the mount. There are a dozen factors that contribute to shots at a mile. I guess I assumed you were shooting at 100 yards or similar and took a measurement on your target or something.
If you sailed a few rounds over your target at a mile and are saying you missed because your EraTac then 100% need to go back to your ballistics and find the mistake.
Need to know more to help any further. What scope, ballistic solver, velocity, density altitude on the day you shot, your ammo and it’s ES/SD, how you arrived at 7.2 mils, etc. I doubt your EraTac if off at all let alone that much.
@Steel head, ya, they now have Mil versions and “ELR” versions that start at a higher elevation.
www.eurooptic.com
Are you assuming your EraTac is off because you didn’t make a hit at a mile?
If so, ya, it’s definitely not the mount. There are a dozen factors that contribute to shots at a mile. I guess I assumed you were shooting at 100 yards or similar and took a measurement on your target or something.
If you sailed a few rounds over your target at a mile and are saying you missed because your EraTac then 100% need to go back to your ballistics and find the mistake.
Need to know more to help any further. What scope, ballistic solver, velocity, density altitude on the day you shot, your ammo and it’s ES/SD, how you arrived at 7.2 mils, etc. I doubt your EraTac if off at all let alone that much.
@Steel head, ya, they now have Mil versions and “ELR” versions that start at a higher elevation.
ERATAC Adjustable Inclination Mounts
ERATAC - Adjustable Inclination Mounts are in stock, best price, no tax, free shipping - Call (570) 368-3920
I'm also having a hard time following your test. I would shoot it like a tracking test.
Go to the range and at 100m put out a tall target and draw a vertical line using a level or plumb line. Mark a dot at the bottom. now fire 3 shots at that dot to confirm your zero. now adjust your ERA tac up 5 mil and shoot at the dot again. (make sure your rifle is perfectly level) now go to your target and measure the distance between your 2 groups. It should be 50cm. I would do it at every marking
Go to the range and at 100m put out a tall target and draw a vertical line using a level or plumb line. Mark a dot at the bottom. now fire 3 shots at that dot to confirm your zero. now adjust your ERA tac up 5 mil and shoot at the dot again. (make sure your rifle is perfectly level) now go to your target and measure the distance between your 2 groups. It should be 50cm. I would do it at every marking
Measured offset at 200 yards was 7.2 mils when the base was set to the 5 mil facet. The offset was checked and was repeated.
I experienced what I believed to be an error at 600 yds when I was at the K&M course and adjusted the base to the 5 mil facet resulting in unknown elevation added and targets missed high. I reset the base to 0 and found my previous zero returned. When I returned home, I recreated the situation as best I could at 200 yards and found that the base was adding 7.2 mils of elevation when set to the 5 mil facet. I have not yet used this base at 1 mile, but I purchased this base specifically so that the next time I shoot at a mile, I don't have to back my scope out to 9x to get the hold over I need.I’m a little confused after re-reading through your first and second post.
Are you assuming your EraTac is off because you didn’t make a hit at a mile?
If so, ya, it’s definitely not the mount. There are a dozen factors that contribute to shots at a mile. I guess I assumed you were shooting at 100 yards or similar and took a measurement on your target or something.
If you sailed a few rounds over your target at a mile and are saying you missed because your EraTac then 100% need to go back to your ballistics and find the mistake.
Need to know more to help any further. What scope, ballistic solver, velocity, density altitude on the day you shot, your ammo and it’s ES/SD, how you arrived at 7.2 mils, etc. I doubt your EraTac if off at all let alone that much.
@Steel head, ya, they now have Mil versions and “ELR” versions that start at a higher elevation.
ERATAC Adjustable Inclination Mounts
ERATAC - Adjustable Inclination Mounts are in stock, best price, no tax, free shipping - Call (570) 368-3920
My scope is a NightForce NX8 4x32. Tac Sol ballistics solver, velocity is 2639 FPS with an SD of 10.
I arrived at the 7.2 mil offset because I shot a 3 round group at 200 yards with the base set to 0, then set the base to 5 mils and shot another 3 shot group with the same point of aim. The result were two groups that were horizontally aligned but 7.2 mils from center of group to center of group. Each group measured ~0.8 MOA center to center.
Hopefully the above clarified it. If not, test procedure was as follows:
200 yd 8 ft. tall target stand with two targets vertically aligned and 5 mils apart center to center, checked via multiple scopes and spotters with reticles.
3 shots at the lower target to establish zero.
Base adjusted to the 5 mil facet.
3 shots at the same point of aim (lower target).
Offset between center of group 1 and center of group 2 measured 7.2 mils, confirmed by other shooters.
Base was reset to 0 mil facet and test was repeated for the remainder of the box of ammo. Results were consistent with first test and the final 3 shots were fired with the base set to the 0 mil facet to confirm a complete return to zero.
When you really start going past 1,000 this ^^^.I’m a little confused after re-reading through your first and second post.
Are you assuming your EraTac is off because you didn’t make a hit at a mile?
If so, ya, it’s definitely not the mount. There are a dozen factors that contribute to shots at a mile. I guess I assumed you were shooting at 100 yards or similar and took a measurement on your target or something.
If you sailed a few rounds over your target at a mile and are saying you missed because your EraTac then 100% need to go back to your ballistics and find the mistake.
Need to know more to help any further. What scope, ballistic solver, velocity, density altitude on the day you shot, your ammo and it’s ES/SD, how you arrived at 7.2 mils, etc. I doubt your EraTac if off at all let alone that much.
@Steel head, ya, they now have Mil versions and “ELR” versions that start at a higher elevation.
ERATAC Adjustable Inclination Mounts
ERATAC - Adjustable Inclination Mounts are in stock, best price, no tax, free shipping - Call (570) 368-3920
Couple questions.
- How did you make the measurement you are referring to above? With a reticle? Tape measure?
- can you share a picture of your NF box model? Looking to see if you bought the F1 or F2 model.
I measured with the reticle in my NF, and my shooting partner confirmed with the reticle in his Kahles.
Picture of my scope box below.
I am new to both ELR and adjustable bases, so I’m open to this being user error. That said, the numbers were repeatable hence my thinking it may not be user error/user error alone.
You could try using it to maximize your scope travel then just lock it.
With that scope you should be able to get 25+ mils total and that should get you to a mile with most suitable cartridges
Ok, I’m at a bit of a loss without being there to help you.
The easiest thing to do if you don’t want to set up your scope in a fixture is set up a target at 100 yards and zero your scope to POA=POI. Adjust your era-tac 5 mils, take a few more shots, and re-measure with your reticle.
Are you 100% sure you are tightening on the flats? Meaning the flat part where it’s marked, not slightly rotated and riding up the nut towards the next mark.
The easiest thing to do if you don’t want to set up your scope in a fixture is set up a target at 100 yards and zero your scope to POA=POI. Adjust your era-tac 5 mils, take a few more shots, and re-measure with your reticle.
Are you 100% sure you are tightening on the flats? Meaning the flat part where it’s marked, not slightly rotated and riding up the nut towards the next mark.
I will ask the question once again which I quoted above:
I don't care about your reticle. Did you verify velocity via chronograph, temp, bullet BC, density altitude, etc? Scope settings are meaningless if you don't have good data. Crap in crap out. The further you shoot the more important "accurate" data is.
I don't care about your reticle. Did you verify velocity via chronograph, temp, bullet BC, density altitude, etc? Scope settings are meaningless if you don't have good data. Crap in crap out. The further you shoot the more important "accurate" data is.
That has no bearing on the fact that his base is adding an extra 2 mils.
Who really cares about the accuracy of the base reading? It's just an indicator (+/-) and not related at all with your ballistics.
If you were trying to adjust it on the fly you would care, especially in a competition. If he has it on a 50 Moa rail and is trying to use it after his scope and reticle maxes out.
Set as needed, confirm change, blast steel far far away.
I don't think its a great option for that style of use.
I would recommend either verification of all adjustments on the era tac and take note of actual slope added or two contact era tac about your concerns.
I don’t really consider it a device you change on the fly and nobody seems to use it that way.
The one device I might trust to do that is the Charlie tarac MK8 and I’d still verify.
Wouldn't use it on the fly, honestly it doesn't make any sense for its intended purpose and design. Otherwise, you may want a Tarac unit.
This is news to me. I bought it because I figured on being able to use it on the fly, in addition to it being handy when I switch barrels on my Desert Tech. I was under the impression that many people used them in this manner.
Edit to clarify, I have seen people use them in this manner at my club and didn’t question it.
I use mine on the fly frequently but I also verified each setting to be 100% accurate.
At this stage, I would buy another ERA-SLACK (2.2 MIL of slack it seems), remount your scope, run this whole scenario again, and see the results. If the problem goes away, the problem is solved and you send the miscalibrated mount back to ERA-TAC and tell them its defective.
If, on the other hand, another ERA-TAC mount gives the same result - then I will wager at good odds that you're doing something wrong or there is another piece of equipment or measurement device that is failing you.
If you're correct and it's the mount, nothing lost with this strategy since you're going to have to replace the defective mount anyway.
But if you're making a mistake, this strategy is going to cost you a good deal of time and hassle; however, the lessons learned along the way will be invaluable, LOL!
Final thought: this is why I hate moving parts. The fewer the better.
Seriously, Good Luck, Bro.
If, on the other hand, another ERA-TAC mount gives the same result - then I will wager at good odds that you're doing something wrong or there is another piece of equipment or measurement device that is failing you.
If you're correct and it's the mount, nothing lost with this strategy since you're going to have to replace the defective mount anyway.
But if you're making a mistake, this strategy is going to cost you a good deal of time and hassle; however, the lessons learned along the way will be invaluable, LOL!
Final thought: this is why I hate moving parts. The fewer the better.
Seriously, Good Luck, Bro.
Make sure that all contact areas are clean, a piece of grit, dirt or sand is probably your issue. I've used mine on the fly before I got my prism shooting Ultra long comp. with my 338 @ over 3K I needed everything I could get. It's a great mount, I like being able to swap my scope around & adjusting the base to get all the elevation from my optic. Would be nice if they offered a mil adjustment wheel for easier math.
You should be testing at each of the settings regardless. Something is definitely wrong being 2.2 mil off at the 5-mil setting. Just make sure that when you've made the adjustment, you are 100% pushing the rear of the scope/mount back down to fully engage the top of the adjustment "knob."
I haven't tested my Era Tac past the 10-mil setting, but that and the 5 mil were dead-on. Before I went out my longer (driving distance) trips, I tested the 5-mil setting at 850 where I set on the fly, and you wouldn't know I changed it. Same thing with the 10-mil setting while shooting at 1500 yards. I should have tried the 15- and 20-mil settings last time I was out in BLM, but there was too much going on with the trip (weather, new location, a couple minor ammo issues) and it slipped my mind.
If one of my settings were to be off, I wouldn't be happy, but if it's repeatable then it's not great, but workable - just know what the actual dope is and adjust accordingly. Though I'd probably still send it back being as far off as it is (if you validate that it's the actual mount).
They have one now.
Similar threads
