Narrowing rear gap for elevation control

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seamaster
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Joined: Sun Jan 16, 2011 6:24 pm

Narrowing rear gap for elevation control

Post by seamaster »

In the past few days, my shot group patterns are like "i"s.

Windage is pretty acceptable, but the elevation is just too much up and down.

Remembered Mikael Nestruev said he shot with almost no gap. I tightened the rear gap to almost no gap.

String of 10's start to appear.

Just wondering if I should continue to use "almost no gap" as my defacto sight picture.

I am NOT too worry about my hold. I have been training with handgrip strengthener which has done wonders to my hold. So I am pretty confident with my hold.

I don't think it is the case of not looking at the front sight. I know if I lose clarity on the front sight, my grouping tends to DROP as a group.

Just wonder if anyone shoots with narrow gap, is it acceptable as a defacto sight alignment, or is it just a crutch for my elevation problem?
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Gerard
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Location: Vancouver, Canada

Post by Gerard »

Funny this should come up. I've been gradually narrowing my rearsight slot on my Pardini K10 over some months and last week was surprised to find that it had 'bottomed out' when trying to make another slight adjustment, with still a slight gap on either side of the sight. This is with the stock 4.5mm front sight.

Then yesterday, in a small fit of pre-match jitters, I thought something like 'hey, I wonder if the commonly held wisdom that the gap on either side ought to be bigger would help?' and adjusted the slot to the standard spacing, bringing my sight picture back to where it was 6 months ago. Shot a handful of targets at home which were full of what I felt were 'yips' either well above or well below the 10. Not exactly an I shape. More like an hourglass. Not satisfied with this nonsense I went ahead and swapped rearsight plates on my 46m to give a similar picture. Same thing, more or less, but on the last target managed to nail 6 10's and 2 solid 9's... and an 8 and a 7. So I worked for the afternoon, then went to the club and shot a few targets. Worse. After 40 shots I went home, with nerves considerably frazzled.

Not wanting to further degrade my perspective I didn't shoot today. Tomorrow we set up the temporary range for the weekend's competition and in the evening I'll shoot a couple of targets and hope for better. And I'm going to re-adjust my rearsight on the K10 back to narrow spacing. I was quite comfortable there. No mental energy wasted in guessing alignment, trying to focus on what looked like 3 very widely arranged elements; the insides of each side of the rearsight and the relatively remote-seeming foresight, which the day before had seemed almost on the same plane as the rearsight with that narrow spacing. Attention taken away from alignment is bad.

It could be that I've been moving in a 'wrong' direction with narrowing the rearsight, but that's closer to what feels natural for me. But take this in context. I've struggled many times with focusing on the front sight blade, but always seem to come back to watching somewhere between midway to the target and the target itself and feeling more comfortable there. I had a lens made so that without any iris this is fairly easy in good light. When using an iris on my lens and stopping it down fairly small, all three planes are in near-perfect focus, and this helps with the other weird element of my habit; I settled on centre aim over a year ago after trying very hard to accommodate a sub-6 area hole and failing miserably. I grew up aiming air rifles at my targets (informally, plinking and hunting as a kid), not below my targets. This seems natural to me. I lose mental focus when below the bull. So what I've said about the relationship between rear and front sight widths is probably heavily related to my aiming at centre and focusing visually on the wrong element. So it goes. Others may or may not choose to chastise such renegade behaviour but that doesn't concern me. I'm the one who has to live with my results.

So long as you don't have a match coming too soon (I'm horrible for making last-minute changes, in work and everywhere else in life, so a bad example) I'd say why not try a different rearsight spacing and see what it does to your groups? Expect to see a couple of clicks elevation change if you do bring the blades together, as there's some aberration coming into play when the gap is almost closed.
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Brian G
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Post by Brian G »

Any known change (trigger weight, sight gap etc) can make you concentrate more as you know there is a difference and can give an improvement in the short term, but when you get used to it, things can slip back to where they were. Only by judging a long term improvement can you be sure that a change works for you.

Having said that I have been shooting for many years and I am still guilty of fiddling trying to find that elusive improvement. :-(
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RobStubbs
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Post by RobStubbs »

The key is all about pattern recognition which is what the brain is very good at, if you let it be ;)

The idea of the wide gaps is exactly for that reason and so you have an equal amount of white at each side as you do between foresight and bottom of the black.

You don't need precise positioning to hit the 10-ring it's pretty large which is why area aiming works. That said, you can equally shoot very precisiely for the reason in my first sentence.

Try different aiming setups to see which works, but don't fiddle, change something then stick with it for a few sessions at least. As Brian said changing things can be enough to make you concentrate more and try harder whilst it's new.

Rob.
David M
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Post by David M »

Also narrow rear sight gaps will cause a earlier onset of eye fatigue during a match and will play hell with different light levels ie different ranges, indoors to outdoors, cloudy to bright etc.
In very bright light narrow gaps tend to flare a lot causing a halo effect. To fix this open up the rear sight.
Narrow gaps are good for slow fire precision, dull even light and short duration.
You will also take longer to take a shot and be trying too hard for a perfect alignment when it really is not required.
Rapidfire needs big gaps to help with the speed of sight picture.
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Gerard
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Post by Gerard »

That's a good point regarding different disciplines. Seamaster didn't specify which he's shooting. For strictly indoors with well regulated lighting conditions and slow fire like AP, it seems a shooter is unlikely to encounter too much flare or uneven lighting from above or to the side. I can certainly see where more open sight gaps might be useful in rapid fire. And when area aiming below the black (not centre aiming) the equal gaps above and to each side of the post make more sense for forming an intuitive sight picture.
shadow
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Joined: Tue Nov 15, 2005 7:56 pm

Post by shadow »

I am farsighted. I found that as I aged and needed a stronger plus eyeglass prescription that I needed more and more light on either side of the front sight. Without the light everything started to blur - getting worse as the match continued. Not sure if other experienced this.
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Gort
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Post by Gort »

I find that having a narrow slit of light on each side of the front sight may seem to allow for more accurate alignment, it is not so. It forces one to constantly make minute corrections and over corrections to alignment. Generally the accepted minimum gap per side should be approx 1/2 the width of the front sight as it appears to the shooter. Rapid fire may require up to one front sight width per side. Below is a link to an old Don Nygord notes, read the section on sights.

http://www.australiancynic.com/NYGORD.h ... out_Sights?

Gort
seamaster
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Post by seamaster »

You are assuming I am looking harder to get alignment with a really narrow gap.

However, I am assuming with a REALLY narrow gap, whatever light imbalance I have on either side is REALLY INCONSEQUENTIAL. Its ACTUAL alignment is as good as a wide gap sight.

I just pull the trigger smoothly with that sight (whatever minute light imbalance might be, I have convinced myself it is as good if not better). Heck with light imbalance, alignment is GOOD.

I think the ELEVATION control with really narrow gap is better than wide gap.
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rmca
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Post by rmca »

I´m assuming slow/precision fire, AP or FP.
I've fiddle a little with this idea in the past, and, at least for me, what worked better was reducing the depth of the gap instead of the width.
If your sights don't have this kind of adjustment, you can cut a black target patch and glue it to the rear sight, thus making the gap shallower. It can be removed very easily without leaving any mark.
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