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Extension tubes and sight plane at 25 yards

Posted: Fri Aug 10, 2018 12:22 pm
by Cumbrian
Will an extension tube (no tuner) assist me in shooting at 25 yards by improving the sight plane? I know it might add a bit of weight and that the wobble factor will worsen. If it would help, what might be a sensible length? For comparison, I am fairly sure that I am better off with 30 or 32 inch barrels rather than 28 or 26 inch for clay pigeon shooting and not just because the longer ones give a steadier swing, and the clay target is usually at least 25 yards distant. (O.K. I know that one target is moving and the other is not.)

P.S. Perhaps I should have used the term 'sight radius'? I'm afraid that I always was a poor maths student - and that was over 55 years ago.

Re: Extension tubes and sight plane at 25 yards

Posted: Fri Aug 10, 2018 4:23 pm
by Shooterer
I added a Mec Berta 2 tube to my 1913/1918 precise stock. It added about 4" to my sight radius and it has helped increase my scores. It also has helped with getting my balance point under my support hand in offhand.

I shoot 50' indoor mostly and had to increase my front insert from, 3.9 to 4.2. Many shooters will go with a larger front tube when extending the radius, but I am cheap and have too much invested in the 18mm system so I just added a 1/8" thick rubber "O" ring to the out side of my sight tunnel and it has worked fine.

In this case, I was able to "Buy Points" (as Rover would say)

Re: Extension tubes and sight plane at 25 yards

Posted: Fri Aug 10, 2018 6:09 pm
by Tim S
Roger,

I found a tube improved my shooting, when I first used one. It wasn't an instant jump to a 99 average, but I think it helped.

If you're concerned about length, I'd start with a longer tube, and cut this down. You can't make a short tube longer.

That said, unless you're making the tube, I'd try one first. If you have a tendency to nerves, the wobble factor is an important consideration.

Re: Extension tubes and sight plane at 25 yards

Posted: Sat Aug 11, 2018 1:44 am
by Cumbrian
Shooterer: that's encouraging - thank you.

Tim: that is also encouraging information - thank you. Yes, good point about nerves!

Roger

Re: Extension tubes and sight plane at 25 yards

Posted: Sun Aug 26, 2018 6:14 pm
by dc.fireman
Just a few things to consider, if you're thinking about adding a sight extension tube:


Increasing your sight radius, will make your rear sight clicks finer - if you're shooting a 1/4 minute sight, you can go down to a 1/5 minute (or more).

If you increase the length enough, you can also change your physical geometry, in regards to head position.

Your target may come into better focus. Generally speaking, you are more precise with the longer sight radius.

You may need a corresponding increase in the size of your front sight aperture.

I have a 36" sight radius on my FWB 2700. I use a 4.5/1.1 aperture size when shooting ISSF 50M targets, without a Centra Eagle Eye. If I use the Eagle Eye .3 magnifier, then I need to go up to a 5.0/1.1 aperture.

Most people I know of make fairly good use of the extension tubes - but there are corresponding changes that usually need to be dealt with elsewhere in the system - as long as you know them up front, its no big deal.

-tc

Re: Extension tubes and sight plane at 25 yards

Posted: Mon Aug 27, 2018 11:25 am
by Cumbrian
dc.fireman wrote:Just a few things to consider, if you're thinking about adding a sight extension tube:


Increasing your sight radius, will make your rear sight clicks finer - if you're shooting a 1/4 minute sight, you can go down to a 1/5 minute (or more).

If you increase the length enough, you can also change your physical geometry, in regards to head position.

Your target may come into better focus. Generally speaking, you are more precise with the longer sight radius.

You may need a corresponding increase in the size of your front sight aperture.

I have a 36" sight radius on my FWB 2700. I use a 4.5/1.1 aperture size when shooting ISSF 50M targets, without a Centra Eagle Eye. If I use the Eagle Eye .3 magnifier, then I need to go up to a 5.0/1.1 aperture.

Most people I know of make fairly good use of the extension tubes - but there are corresponding changes that usually need to be dealt with elsewhere in the system - as long as you know them up front, its no big deal.

-tc
Thank you very much for your interesting and encouraging post. Just a couple of questions arising:

1. Head position - is an extension likely to cause you to raise your head (which I wouldn't at all mind happening)?

2. 1.1 ring thickness seems very thin to me for a foresight that is even further away from you. Is this something that is special to you or do others also have no problems with it, so far as you may know? I'll admit that my eyes are no longer young and that I seem to prefer a thicker ring.

Roger

Re: Extension tubes and sight plane at 25 yards

Posted: Mon Aug 27, 2018 11:57 am
by Tim S
Roger,

1) Yes, adding a tube can affect your elevation. If I remember rightly, increasing the sight radius effectively lowers the foresight slightly; I do get left and right confused though, so might be t'other way round. Against that some tubes are slightly wider than the barrel, placing the foresight higher.

2) It's personal choice. Some like the thinner ring, as the sight picture is less cluttered. A thin ring also allows a slightly smaller aperture. I like a very thick ring, but a large-ish aperture. In theory if you increase the aperture diameter for a tube, you should increase the ring thickness to maintain the same proportion. However the same ring thickness may look right.

Re: Extension tubes and sight plane at 25 yards

Posted: Tue Aug 28, 2018 1:39 am
by Cumbrian
Tim,

Many thanks as usual. Very helpful.

I am now going to look out an extension tube I made some time ago.

Roger