Does a low optic cut really matter

[dontshakepandas]

I strongly prefer a lower RDS on a handgun, because the height affects my index and wrist angle. However, having a straight head and neck position is very important. Interestingly @GJM, I used to run a low scope height on my precision rifles, but found that taller rings yield a better cheek weld, and face position. Many rifle shooters are moving away from the barely off the barrel scope height. Tall RDS mounts are all the rage for carbines now too.

I agree with all of this. I prefer my RDS on a handgun to be as low as possible as long as I can get BUIS that maintain a lower 1/3rd or lower sight picture. It just makes the index more natural for me, and could potentially increase concealment a bit (same optic window but smaller overall footprint). I'm not overly picky between very slight differences like company A vs company B for the same optic/gun combo, but do have stronger preferences to specific platform/optic combos to others. For example, I really prefer my RDS Glocks over the RDS P30 I had.

For rifles, I like tall mounts and am using the Unity Tactical mounts on two guns, and have a Badger 1.7" mount on my precision oriented gun. The 1.7" makes it a lot easier for me to get a good cheek weld, especially when wearing hearing pro.

[Darth_Uno]

Once you do get used to one system, it affects your grip and presentation angle like @Clusterfrack says.
.

That’s true for me. I’m so used to milled pockets I can definitely tell a difference when I shoot MOS guns. If I’d only ever used MOS it wouldn’t be inherently “worse”.

[P226SAOFan]

Lower the RDS, the less obnoxious sights you need as well, which is nice.

[RJ]

I was wondering about this question last night as I was deciding what range to setup my MRDS zero for. Being brand new to optic shooting, I've recently acquired a Holosun 507c v2 for my Glock 34 MOS to get my feet wet and see what this "dot" is all about. I am about ready to get it installed with permanent parts which are on the way, so I've been watching various YT dudes and how they zero their MRDS. The variation is interesting.

So I was thinking about this "does it matter" thread. With a pistol, and common ranges out to 25 yards, seems like the height of the optic can be used to predict the theoretical impact point, since you know the range of the target, assuming the bullet and laser are straight lines. What differs is the distance that you "zero" the optic for, right?

Since I know the height (ok, approximately) of the center of the optic on my setup, and I have to decide what range to zero at, a question would be what would be the best zero in terms of average error on the remaining typical ranges?

I decided to use 7, 10, 15 and 25 yards and set up a simple calculator spreadsheet to compute this. For the "error" i..e high / low of the bullet vs. zero with fixed optic height, I am pretty sure (somebody check my math) that the law of similar triangles applies, so the equation would be:

Err = (R - Rz) * (H / Rz)

Where

Err = Error up or down, where up is positive, and down is negative
R = Range
Rz = Range at which you zerod the optic
H = Optic height above the bore axis

All with appropriate unit conversions, of course.

I measured my optic's height or H (G34 MOS + HS 507c on a factory MOS plate for Dry Practice) as 0.919" . Putting this all into a spreadsheet to generate some actual numbers:



Based on this, it appears my least average error (based on the ranges I picked anyway) is if I zero at 10 yards. Since I shoot a lot there (The Test etc.) that's probably what I'll use for my optic setup.

Interestingly (to me anyway) is if I zero at 10 I will have to move my "hold" at 25 yards (for groups) lower a bit, with the dot. The spreadsheet predicts about 1 1/2" (1.379") so perhaps holding on the bottom of the 10 ring (3.36") on a B-8 should land rounds in the center of the X ring (1.695"). (assuming I did all this right). To nail center of 1' squares at 3 yd, I'll need to aim high, perhaps 1/2" (0.643") or to the top of 1" squares or 2" circles of Dot Torture.

[GJM]

After you shoot the dot enough, your brain will, at a subconscious level, take care off offset for you. I, and most people I know, zero at 25 yards, although I have one friend that thinks 12.5 yards is ideal. Don’t over think this, trigger control will be way more important than some small increment of zero difference.

[RJ]

After you shoot the dot enough, your brain will, at a subconscious level, take care off offset for you. I, and most people I know, zero at 25 yards, although I have one friend that thinks 12.5 yards is ideal. Don’t over think this, trigger control will be way more important than some small increment of zero difference.

Well I'm glad that's the same as irons.

[taadski]

I know this is a thread about dot height on pistols, and in that vein, I’m not super fussy. I go back-and-forth between an SRO, a couple RMRs and a Romeo one on like pistols. I find the window size, even on the smaller RMRs, to be large enough to ameliorate slight differences in mounting heights. For me anyway.

For rifles, I like tall mounts and am using the Unity Tactical mounts on two guns, and have a Badger 1.7" mount on my precision oriented gun. The 1.7" makes it a lot easier for me to get a good cheek weld, especially when wearing hearing pro.

For shooting fast, I like a higher dot on my PCC.

I believe “lower is better and a smaller (dot) is better” comes from precision rifle shooting. Max M made this exact point earlier this week on his podcast.

Interestingly...I used to run a low scope height on my precision rifles, but found that taller rings yield a better cheek weld, and face position. Many rifle shooters are moving away from the barely off the barrel scope height. Tall RDS mounts are all the rage for carbines now too.

In regard to these comments, if the OP wouldn’t mind a brief derail...

I bounce back and forth between LPVOs and dots on my carbines quite a bit. I have absolutely noticed the difference in cheek weld/head position between a lower 1/3 RDS mounts and a more traditional scope mount height. I’ve been seriously considering playing with a taller scope mount (like the Larue LT135) to make going back and forth a little more consistent.

I’d love any additional thoughts/perspective/suggestions if anyone cares to share.


T

[JCN]

I was wondering about this question last night as I was deciding what range to setup my MRDS zero for. Being brand new to optic shooting, I've recently acquired a Holosun 507c v2 for my Glock 34 MOS to get my feet wet and see what this "dot" is all about. I am about ready to get it installed with permanent parts which are on the way, so I've been watching various YT dudes and how they zero their MRDS. The variation is interesting.

So I was thinking about this "does it matter" thread. With a pistol, and common ranges out to 25 yards, seems like the height of the optic can be used to predict the theoretical impact point, since you know the range of the target, assuming the bullet and laser are straight lines. What differs is the distance that you "zero" the optic for, right?

Since I know the height (ok, approximately) of the center of the optic on my setup, and I have to decide what range to zero at, a question would be what would be the best zero in terms of average error on the remaining typical ranges?

Based on this, it appears my least average error (based on the ranges I picked anyway) is if I zero at 10 yards. Since I shoot a lot there (The Test etc.) that's probably what I'll use for my optic setup.

Interestingly (to me anyway) is if I zero at 10 I will have to move my "hold" at 25 yards (for groups) lower a bit, with the dot. The spreadsheet predicts about 1 1/2" (1.379") so perhaps holding on the bottom of the 10 ring (3.36") on a B-8 should land rounds in the center of the X ring (1.695"). (assuming I did all this right). To nail center of 1' squares at 3 yd, I'll need to aim high, perhaps 1/2" (0.643") or to the top of 1" squares or 2" circles of Dot Torture.

The issue winds up being if you don’t know exactly what the target distance is.
Or it’s moving.

Or you’re moving.
With a Holosun 507c you have the large reticle and that can help using different sighting rings for different holds.

I personally zero my handgun RDS at 25 yards and at 7 yards I just aim on the upper edge of the scoring knowing that it’s going to be under that if I do my part.

My issue with 10 yard zero is it’s hard to actually accomplish that accurately sometimes without a ransom rest, so I use 25 yards to make it more clear where the impact actually should be.

Get a good bench rest. And a bore sight if you’re going to do this a lot.

I got the wheeler magnetic muzzle laser and it has paid for itself many times over. It gets me close right away and is a good quick check if I think it’s gotten knocked off zero.

[RJ]

I was wondering about this question last night ...

So I had a think on this some more, and decided that I didn't account for a few things. Relative to my (short) USPSA experience, I generally shoot close range with a target sight picture fast, so having a 3 yard range in the computation doesn't make sense. As well, I've had a match or two where they had targets out to 35 yards, so I wanted to factor that in.

In terms of an evaluation metric, I decided just to rank zero distances based on the total "spread" of the errors. Looking at the reworked table...



...the best option now appears to be to zero at 25 yards.

Zeroing at 25 yards has a max theoretical "spread" of 1", between ranges of 7, 10, 25 and 35 yards. Zeroing at 25 also doesn't make me think, do I need to hold over or under, inside of 25, since everything under 25 is just a hold less than an inch, and surely to goodness there's no way I'm holding steady within half an inch or so that it would matter in match conditions anyway. And I can basically use that same hold for a longer distance 35 yard target. So: zero at 25, then for all ranges, work on trigger control, placing center of dot on target.

Interesting exercise.

[NoTacTravis]

Just to chew on the point some more and thoroughly overthink the zero-ing point...

If we're talking shot difficulty for USPSA, in most matches at 25 yards aren't you normally targeting the center alpha zone and not the head box? With a much larger vertical scoring zone to forgive the 1" gain or loss in bullet elevation caused by zero-ing distance, I could see it functionally mattering very little at that 25 yard distance as encountered in a match setting. However, I am kind of assuming open targets at that distance for that scenario and not hard partials at 25 yards.


However, a 15 yard headbox could very well be encountered and its much smaller scoring zone is more likely to result in dropping out of the A zone or lifting over the target. I know I feel like I'm always perforating the edge of the upper A zone at that distance (obviously my own poor marksmanship at work).

I'm pitching that the tightest shots with that margin of zeroing error to actually matter could very well be the 15 yard upper "A" zone, distance the hardest swingers or Texas stars are placed at, or that 12-14 yard tight partial, and not the 25 yard open target?

Plus, since I can't shoot groups at 25 yards but have a shot at taking my time on a 1 inch paster in a 15 yard headbox to zero an optic, I'm throwing that distance into the discussion as a potentially valid option.

Thoughts where I've gone astray with that logic?