Fore Sight

[Martin Catley]

We were having a discussion on Fore Sight diameters and it was interesting listening to the various answers. We are actually shooting indoors 25 Yards on an aiming mark reduced from 50 Mtrs.

In 50 Prone would or could some of you give an idea of what you are using and possibly what type of sight also?

[patriot]

Rightsight 30 mm with a .5x lens mounted on a BeeSting Tuner. Iris opening depends on sight radius, magnification, target black size, and the amount of white one prefers. On a 27 inch barrel with a 7.5 inch tube I'm at 7.4mm on the Gehrmann front iris for both 50 and 100 yard conventional & metric targets. The perception is there is slightly less white at 100, but not enough to adjust the opening. I did have a glare problem outdoor with south facing targets reflecting the sun, particularly in the winter. I invented a front sight filter with the center cut out (full light on the target bull) which resolved the issue.

Mark

[Martin Catley]

Thank you Patriot unfortunately I should have said I am currently shooting to ISSF Rules so no magnification allowed! What you are doing sounds very interesting though. Personally I am looking through a naked Barrel using about 4.4 in an adjustable 22ml Iris. I am an older shot using a standard length barrel (27) I do have a Tube but am not sure of the help it is for me it comes on and off every now and then. Very long sighted using a lot of + to even see a fore sight ring.

[Tim S]

Martin,

for what it's worth, I think I have a 5.4mm (24in barrel + 12in tube, no magnifier). On a bare 27in barrel I think I had a 4.0 or 4.1mm - that was a long time ago. The actual element is a glass iris with a very thick ring, but I also have hi-ends that I like a lot.

[HWN1011]

Hi Martin

Before I added an extension tube I was using 3.9mm foresight element in 18mm foresight tunnel.
I have found the new clear foresight tunnels to be very good much more consistent with different light.

Henry

[Andre]

Stock Anschutz 27" barrel, w/11" aluminum tube using a 3.6mm insert.

[Tim S]

Stock Anschutz 27" barrel, w/11" aluminum tube using a 3.6mm insert.

Crikey that is small. 3.6mm would be a tad small for me without the tube. That 3.6mm equates to a 2.7mm or so without the tube. I hope your hold is very, very tight.

[HWN1011]

Stock Anschutz 27" barrel, w/11" aluminum tube using a 3.6mm insert.

Crikey that is small. 3.6mm would be a tad small for me without the tube. That 3.6mm equates to a 2.7mm or so without the tube. I hope your hold is very, very tight.

I would have thought it was a typo and should have been 4.6mm. If it is 3.6mm on an 11" tube Andre is some sort of superhero :-)

[WesternGrizzly]

I have a 35 inch sight radius, and use a 3.8-4.0 depending on how bright it is.
Matt

[ZD]

Foresight ring size is one of the most hotly debated subject in shooting from my experience. Based on my experience, both personal and when I coach bigger is better. I almost always see a positive change in shooter who go up in size, I have yet to see it hurt them. Larger apertures allow for easier trigger release, as you are less likely to spend time trying to get your aiming mark perfect. You need to have a aperature big enough such that your muzzle movement will not cause the rifle bull to bounce back and forth inside the element. Larger foresight rings also allow for more light; if you are having trouble seeing, often times opening up your front iris, or sticking in a larger element helps. It seems illogical that larger foresight elements allow for easier aiming, but they do. Bottom line is you need to be able to get the shot off quickly, as your NPA, natural instincts and routine allow you to recognize a ten, often subconsciously. This is harder to do with a smaller ring, lots of shooters over hold because their foresight ring is to small, they will struggle to get everything perfect. As far as minimum size goes, I was always told at least a 3-4 for prone, 3-8 in standing, 3-6 in kneeling, on a standard length barrel of about 26-27 inches, no bloop tube. I have a 36 inch sight radius now, and used a size as large as a 5.1 in prone. Might be a little big, but it works for me, shot better prone with the bloop tube when I switched a year ago. JP O'Connor, who writes the "on the firing line" series for USA shooting, made a chart about foresight ring size, and recommended to me when I spoke with him to go up a tenth of a size for every inch you extend past your barrel length. He likes large foresight rings, or aperatures. To compare to Matt, personally I would not recommend to anyone to use a 3.8 or 4.0 with a 35inch sight radius. Having said that, eyesight does effect how small you can make your aperature. However, Matt is a far better shot then me, and an experienced national team member. It works for him. Like I said, this is a subject often not agreed on in the shooting world.

-Zach

[Tim S]

Zach,

if Matt measured his sight radius from the rearsight eyepiece, 3.8-4.0 doesn't seem that small. An Anschutz barrel/action is around 33in long, and the eyepiece is normally near the back of the bolt. If he was measuring only the barrel + tube, then I agree.

[KennyB]

Yes - out of interest, where are we measuring sight radius from? Foresight to Rearsight or Foresight to eyeball.

FWIW, I have a 27" barrel with a 4" extension - my sight radius is 37 & 1/2" foresight to eye and I use a 3.8 (1.0 ring thickness) High-End. By my reckoning this gives me a shade under the 3MOA of white that is the suggested minimum.
I have also been known to use a deep pink perspex element with a 3.8 black ring - that really makes the white ring stand out!
I like the thin rings much better than thick ones. I have an adjustable foresight but the ring is so thick that I find it unusable and my aim is all over the place.

Most of my clubmates tend to use 3.8 to 4.1 (1.4) high-ends on a 27" barrel.

Many years ago when I was using a 12" tube, I had a 3" as well for windy conditions. There was one windy detail at Bisley where I swopped the tube but accidentally left the 4.8 element in the foresight instead of putting in the 4.0 I usually used. My score was pretty much the same although the sight picture was like a pea in a bucket.
Going smaller I'll tend to shoot some very tight center tens and then have a shot where the aim is in the 9 ring although the sight picture appears the same...
SCATT is a great help with this kind of thing.

K.

[ZD]

Tim,

Good point. Didn't think about where we would be measuring from. I was only referencing barrel length, but you could very well be right about sight radius being measured from the rear sight, which would make more sense anyway.

-Zach

[WesternGrizzly]

I measure my sight radius from the back of the rear iris to where the element sits in the front tube. The sizes I use are:
Prone: 3.8-4.0
Kneeling: 4.3
Standing: 4.0 but I move my sight about 6 inches closer.
Matt

[Andre]

Stock Anschutz 27" barrel, w/11" aluminum tube using a 3.6mm insert.

Crikey that is small. 3.6mm would be a tad small for me without the tube. That 3.6mm equates to a 2.7mm or so without the tube. I hope your hold is very, very tight.

I would have thought it was a typo and should have been 4.6mm. If it is 3.6mm on an 11" tube Andre is some sort of superhero :-)

Actually I was wrong, I had a look at my insert this morning. It's a 3.4. Yes, 3.4 not 4.4.

Here's the story, a coach of mine was rebuilding my standing position and I said my iris was a tad large. He recommended a 3.6, (not realizing I had a tube) however it was missing from my set. (Turns out it was in a FWB air rifle) so I tried a 3.4, it was tiny at first but my score really went up. I just learned to shoot with it, and I like it now. In prone and sometimes kneeling the black stays in, but in standing I do have to pick my shots some days. I hope a superhero shoots better than a 560!

I use the same insert for 50 and 100 yard.

I am going to grind a glass aperture soon, just because I can, and might try for something like a 3.9mm.

For reference, I use around a 3.3 - 3.6 air rifle on maximum sight radius. Iris set bigger and my score drops.

[Tim S]

Andre,

Does your coach now know that you use a tube? And he has not commented on your aperture size?

Personally I'd recommend forgetting a 3.9mm element, and skipping straight to a 4.8mm- - your coach's suggestion of 3.6mm scaled up for an 11in tube. Perhaps even a range of sizes so you can have a slightly larger one for standing.

What targets are you shooting at by the way? I believe that most of the comments above are based around the ISSF 50m target, or scaled versions, all of approx. 8 MOA dia.

[Cumbrian]

I have found this discussion extremely interesting and helpful. I wonder if the existing contributors, and perhaps new ones, could let me know what they find best for the ring thickness of the foresight? I have been using an adjustable foresight that gives a minimum thickness of 2.2. This appears to be out of line with the thickness preferred by others. (See also the adverts for Centra High End elements on the Intershoot and Edenkillie websites, where 1.00 < 1.4 are variously cited as the most popular). Last night at our 25 yards range I tried a Centra High End with 1.0 thickness (with a 5.2 diameter, because I use a 0.5 eagle eye at my age) at the end of a standard Anschutz 1800 series barrel, no extension tube. I found the experience a bit uncomfortable, compared to my usual 2.2 < 2.5 ring thickness, also with a 5.2 diameter. I seemed to be straining to get it all together. And the results were mixed. Is it worth my while to persist i.e. do I simply need to get used to the new thickness? I also have a 5.5 x 1.3 High End that I am thinking of trying next. Grateful for all opinions and advice.

(Please excuse my delayed acknowledgments of any responses as I am away on holiday and beyond internet reach for the next 7 or 8 days.)

[Tim S]

Roger,

firstly, ring thickness can be as personal as the aperture size. Some people prefer very thin elements, and others prefer thick elements. I don't thick not a matter of right and wrong. I would not expect that a 1.0mm ring would look right the first time after prolonged use off a much thicker element, not unless the 2.2mm had always seemed much too thick. I recently changed form a 1.4mm high-end to a 2.0mm iris, and it took a session or two to become accustomed to the thicker ring, even though it felt comfortable.

You might also find that with a thinner ring you need a slightly smaller aperture to maintain a balance of dark and light.

[Cumbrian]

Tim,

Rather belatedly, many thanks for your helpful reply. I hope that others may yet come forward with their suggestions and opinions. I tried out several Centra High End inserts last night at the range (25 yards only) and my tentative conclusion is that a narrow ring does help, though I have no idea of the optical reason for this. With my 0.5 eagle eye (in all cases) I found that 5.2 x 1.0 was too demanding for my 69 year old eyes, not enough white around the aiming mark and the ring too thin. The 5.5 x 1.3 seemed a pretty good compromise to me, and I managed a 96 on a match card with it (nerves and all), which is above my long term average, and there were no 8s(!). The 5.7 x 1.2 appeared to provide a near ideal amount of white, but I think a 1.3 ring would be better. So I shall order a 5.7 x 1.3 in the hope that this will prove to be the correct combination.

For those interested, there is an authoritative article in US Shooting News, Jan-Feb 2011 (www.usashooting.org), on foresight size, recommending a considerable degree of white around the aiming mark and a thin ring but unfortunately not specifying any dimensions of the latter, which was cited by Scott J, with a link, in a Targettalk discussion on 30 Jan. 2015 ('Size of foresight aperture').

Roger

[lyoke]

I have 27" and I was using a 3.4. I just put an 11" tube on my rifle. I normally shoot 50 ft or 50m but I have started recently shooting 100 yd prone matches. I used the 3.4 and did decent.... The largest size I have in my set is a 4.0. Would it be recommended that I go straight to the 4.0 for my next match (100 yd prone) and order some new larger inserts for the future?

Thanks.

Lake