12" Extension Tube Question

GaryD · Post by **GaryD** » Fri Oct 14, 2011 1:01 pm

I am using a 3.8mm element in my foresight at the moment but I intend to put a 12" Ex Tube on the rifle.

Has anybody any recomendation as to what size foresight I will have to go to at the maximum distance as I will need to order one.

P.S Best of luck to Wales in the Rugby tomorrow.

KennyB · Post by **KennyB** » Fri Oct 14, 2011 1:56 pm

I've gone for a 5.0 on my 12" tube - 4.7 I found marginally too small.

Although, if you go smaller you can always move the foresight back towards you a bit...

K.

10x · Post by **10x** » Fri Oct 14, 2011 2:02 pm

Hello Gary
I was told the rule was .1mm for every inch added to forsight...
which would give you about 5mm the same as Kenny.
Regards Adrian

GaryD · Post by **GaryD** » Fri Oct 14, 2011 3:32 pm

Thanks for the replies

One of the reasons I was asking is because I was looking to buy the Centra Duo adjustable forsight but they come in two sizes as shown below

Anyone any thoughts which one might be the best for use with the tube as originally I was going to go for the first one of 2.8-4.8, but now after your comments I am not so sure.

2,8-4.8 inner /
6.4-9.0 outer

3.8-5.8 inner /
7.6-10.2 outer

TennJay · Post by **TennJay** » Sat Oct 15, 2011 8:41 am

I like the 5.0. I have tried larger and smaller, but 5.0 seems to do the trick.

GaryD · Post by **GaryD** » Thu Nov 10, 2011 1:16 pm

I have been using my extension tube with a 5.0 element in a 18mm foresight for a couple of weeks, but I would like to change to a 22mm foresight in order to give me a better sight picture.

The problem I have is that I would like to use it with an Eagle Eye diopter but the only elements that I can find to fit a 22mm foresight seem to be the Centra high end ones which I believe will not work with the Eagle Eyes.

Has anyone got any recommendations to overcome my problem.

Tim S · Post by **Tim S** » Thu Nov 10, 2011 2:59 pm

Gary,
get one of Barry Nesom's 22mm turnover foresight tunnels. He'll thread the front of the tunnel for 18mmm inserts. Plus no more clicking up for 100 yards, just turn the tunnel and job done.

His phone no is 01751 473124

GaryD · Post by **GaryD** » Thu Nov 10, 2011 3:56 pm

Hi Tim,
I didn't think about asking him, which is a bit dull of me as the extension tube I am using is one of his.
I am also using one of his turnover sights at the moment, the 18mm one.

I will give him a ring tomorrow.
G

Globesmasher17 · Post by **Globesmasher17** » Thu Nov 10, 2011 4:48 pm

I ended up going for a slightly smaller ext tube.
The 12" just seemed to put the front sight way to far away so I shortened it to an 8" tube which yielded a full 40" sight radius. With that sight radius I find that 4.2 on the front sight iris aperature seemed to work OK on an ISSF 50 Meter target for a sight picture.

I guess it all boils down to that "personal choice" in how one wants to see the "proportions" of ring and iris sizes in the eventual sight picture. Some guys who shoot next to me have theirs cranked out open to 5.0 and more in some cases.

GaryD · Post by **GaryD** » Thu Nov 10, 2011 5:28 pm

Globesmasher17 wrote:I ended up going for a slightly smaller ext tube.
The 12" just seemed to put the front sight way to far away so I shortened it to an 8" tube which yielded a full 40" sight radius. With that sight radius I find that 4.2 on the front sight iris aperature seemed to work OK on an ISSF 50 Meter target for a sight picture.

Its possible I might end up doing the same as you, the advantage I have with my tube, is that the foresight mount runs the whole length of the tube so I can slide it back and fore hopefully to find the optimum position.

Do you use an 18mm or 22mm forsight on yours

GaryD · Post by **GaryD** » Fri Nov 11, 2011 2:39 pm

Tim S wrote:Gary,
get one of Barry Nesom's 22mm turnover foresight tunnels. He'll thread the front of the tunnel for 18mmm inserts. Plus no more clicking up for 100 yards, just turn the tunnel and job done.

His phone no is 01751 473124

I spoke to Barry this afternoon about the 22mm foresight, but after speaking to him I ended up a bit confused, I tried phoning him back but could get no answer.

He seemed to say that his 22mm foresight will take the 22mm elements but the 18mm eagle eyes screws into the front of the foresight at the target end, which seems to me a bit strange. Am I wrong.

Tim S · Post by **Tim S** » Sat Nov 12, 2011 4:37 am

Hi Gary,

no it's not strange to have the eagle eye at the front of the tube. You do have to increase the size of the foresight aperture to suit the enlarged aiming mark.

Globesmasher17 · Post by **Globesmasher17** » Sat Nov 12, 2011 11:37 am

GaryD wrote:
Globesmasher17 wrote:I ended up going for a slightly smaller ext tube.
The 12" just seemed to put the front sight way to far away so I shortened it to an 8" tube which yielded a full 40" sight radius. With that sight radius I find that 4.2 on the front sight iris aperature seemed to work OK on an ISSF 50 Meter target for a sight picture.
Its possible I might end up doing the same as you, the advantage I have with my tube, is that the foresight mount runs the whole length of the tube so I can slide it back and fore hopefully to find the optimum position.

Do you use an 18mm or 22mm forsight on yours

Gary:
You're lucky if you can slide your front sight all the way back and forward on your tube. In that way you can adjust your sight radius to whatever you want it to be. Nice. Lucky you.

Currently I have an M18 front sight. It looks too small so I placed the fatter ring that came with the sight onto the front of the tunnel. It now looks like an M22 with a big fat, thick ring for a tunnel. I am currently in the process of scrounging up cash to buy an M22 ........... the tunnel is cheap, it's the variable ring iris that isn't - yikes!!!

GaryD · Post by **GaryD** » Sat Nov 12, 2011 6:10 pm

Tim S wrote:Hi Gary,

no it's not strange to have the eagle eye at the front of the tube. You do have to increase the size of the foresight aperture to suit the enlarged aiming mark.

Hi Tim,

I spoke to Barry again this morning and I will be ordering one of his 22mm turnover sights on Monday.
He assured me that the 18mm Eagle Eye will fit in the front.

He also said that he has seen some good shooters using his Turnover sight the other way around. Strange!!!

GaryD · Post by **GaryD** » Sat Nov 12, 2011 6:23 pm

[/quote]
Gary:
You're lucky if you can slide your front sight all the way back and forward on your tube. In that way you can adjust your sight radius to whatever you want it to be. Nice. Lucky you.

Currently I have an M18 front sight. It looks too small so I placed the fatter ring that came with the sight onto the front of the tunnel. It now looks like an M22 with a big fat, thick ring for a tunnel. I am currently in the process of scrounging up cash to buy an M22 ........... the tunnel is cheap, it's the variable ring iris that isn't - yikes!!![/quote]

Hi Globesmasher17,
I agree with you that the variable ring iris is expensive so I am going to order a selection of 22mm plastic foresight elements to try first.
Hopefully it will give me some idea as to what size I prefer as I would like to use the Centra High End elements if possible but at about £15 a time it would cost a fortune