apertures

[FoxyRifleChick]

hi,
we are having a club debate on front aperture size. we shoot three position smallbore indoors and have a few rifles with bloop tubes. several shooters use 3.8 and 4.0 in all positions, while some change each position, using 3.0 to 3.6 for standing. we don't have any adjustable frunt apertures. we would just like some feedback on other shooter's experiences and preferences. thanks!

[Tony Nielson]

There is an interesting article at:

http://projects.chatrifleclub.org/targapert.html

I think there is benefit to what is written there. I have tried it in offhand and have improved my scores. I also think I have a better sight picture and I am not fighting the sight picture during the shot. The charts are a little hard to interpolate that are given so I crunched the equations and came up with the following.

R equals sight radius in inches
B equals bull size in inches
r equals distance to target in inches

According to the article:

Optimum aperature size equals (1.8 x B x R) / r

Obviously the 1.8 is the mutiplier in comparing the MOA size of the target to the MOA size of the front aperature. I have found that I actually like 1.6 more. Clearly a personal preference. I would assume (thats dangerous) that one should stick with the same multipier when changing to a different size target, a different distance, whatever.

Hope that helps

Tony Nielson
Nielson Brothers Arms, Inc.
http://www.nielsonbrothersarms.com

[Sparks]

Generally, use a larger foresight for standing than for prone. I use 4.5mm for standing, occasionally dropping down as low as 4.0mm if it's a well-lit range; but for prone it's from 3.9mm down to 3.6mm or so.

[snapy050]

I started off using 3.0 in prone as at that time there were no other inserts at our club. Later i started using 3.6 for prone, kneeling and 3.8 for standing at 50m. These are generally lower ends of suggested as maybe I was using 3.0 and I still like smaller things. I dont know why but 4.2 seems perfect to me in standing at 10m. However the logic behind the inserts is that we are better of bringing any object to the centre of a larger circle than of a circle of almost equal size. The other thing is that if we use smaller inserts, Its human nature to see the white glare around any black object so we might mistake that to be the gap between iris and aperature.

In general, Its on your choice to use what ever inserts your eyes are comfortable with. What I would suggest is to try out different inserts starting from big ones and decreasing the size while checking the group size and how it feels on each occasion!

hope that helps!
Rajesh.
Indian National Shooter.