The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Gear and Accessories

Reply
 
Thread Tools
Old December 16, 2012, 08:53 AM   #1
NHSHOOTER
Senior Member
 
Join Date: November 26, 2012
Location: Concord NH
Posts: 192
1" tube versus 30 mm tube??

I have a ruger 77 that came with 1" scope mounts, now I am thinking about a scope with a 30 mm tube, I am not good with metric conversions, is there that much difference? What do I need to do?
NHSHOOTER is offline  
Old December 16, 2012, 09:13 AM   #2
4runnerman
Senior Member
 
Join Date: January 16, 2010
Location: Minnsota
Posts: 2,656
Yes the difference is very visual. You will need 30 mm mounts. I have almost all 30 mm scopes now,so needless to say i have a pile of 1 inch mounts laying around. What i have found is as soon as you get to the more high power scopes you run into 30 mm tubes. I can't say the light is that much better. I have one rifle with a 1 inch tube and when i shoot early in the morning i can see no difference in light gathering. I am no scope pro for sure but i think when you get to higher power scopes you objective gets bigger,so the need for a 30 mm scope tube. Im sure someone else with a lot more knowledge will chime in
__________________
NRA Certified RSO
NwCP- Performance Isn't Optional
4runnerman is offline  
Old December 16, 2012, 09:18 AM   #3
NHSHOOTER
Senior Member
 
Join Date: November 26, 2012
Location: Concord NH
Posts: 192
Thank you for the quick response 4runnerman. I think I will be waiting to change then, just put the 4-12 on the ruger but bushnell has a 2.5 -16 that looks real interesting..
Thanks again
NHSHOOTER is offline  
Old December 16, 2012, 09:34 AM   #4
stubbicatt
Senior Member
 
Join Date: September 15, 2007
Posts: 974
According to the individual at Leupold who responded to my email, the 30mm tube allows a greater range of adjustments. The light transmission is determined by the objective lens.
stubbicatt is offline  
Old December 16, 2012, 10:44 AM   #5
darkroommike
Senior Member
 
Join Date: August 27, 2011
Location: western Iowa
Posts: 197
One inch is about 25mm. It's not that the diameter is that much larger but the area (think garden hose). Area of a 25mm tube 506mm, area of 30mm tube is 706mm and transmits about twice as much light. It's also the size of the front glass, bigger glass has better light gathering power. Many tubes have flared front ends to support larger glass.
darkroommike is offline  
Old December 16, 2012, 11:53 AM   #6
SSA
Senior Member
 
Join Date: August 1, 2010
Posts: 320
The tube diameter has no effect on the optical performance of the scope. It has no effect on light transmission.

Things that matter are quality of glass and coatings, objective lens diameter, magnification, and exit pupil. Size of the scope tube does not figure into the equation.

For best low light performance, you want the exit pupil of the scope to be at least as large as the entrance pupil of your eye.
SSA is offline  
Old December 16, 2012, 03:27 PM   #7
wogpotter
Senior Member
 
Join Date: September 27, 2004
Posts: 2,718
Quote:
According to the individual at Leupold who responded to my email, the 30mm tube allows a greater range of adjustments. The light transmission is determined by the objective lens.
This.

Actually the light gathering is determined by the objective lens, but at the point where the internal adjustments kick in the "pencil of light" from that lens has been tightened down to about 1/8" (3mm or so) so adding diameter allows more movment of the internal tube which is how you adjust your crosshairs.

Think of it this way. Draw a 1/8" circle on paper then draw a bigger 30mm (1 3/16") circle round it. Now draw a 1" (25.4mm) circle inside of the 30mm one, but outside the 1/8" one & you'll see how much more movment is possible for a scope with a 30mm tube as opposed to a 1" tube.***

Light Transmition is governed by design of the glass, optical coating efficiency & so on.

*** yes I know, these are approximate, but it does give a visual clue to how optical performance works. the 1/8" beam of light thrown back onto the internal tube is way smaller than either of the other 2 measurements, but it can "wander about more" in a bigger circle..
__________________
Allan Quatermain: “Automatic rifles. Who in God's name has automatic rifles”?

Elderly Hunter: “That's dashed unsporting. Probably Belgium.”
wogpotter is offline  
Old December 19, 2012, 04:06 PM   #8
Erno86
Senior Member
 
Join Date: September 22, 2012
Location: Marriottsville, Maryland
Posts: 462
You might need higher mounts for the 30 mm scope. Do not allow the scope to touch the barrel or reciever.
Erno86 is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 06:22 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2013 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.07294 seconds with 9 queries