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Who knows about recoil springs on old scopes (Unertl, et al.)? Login/Join 
Freethinker
Picture of sigfreund
posted
The post by tacfoley about his old rifle and the picture of the Tasco scope with recoil spring reminded me of a question I’ve long wondered about: Why the spring?

One post I found on a different forum claims that it was because scopes of the era weren’t as rugged as those today, and the lenses could come apart due to recoil. The spring helped cushion the sight from the recoil shock. Another post, though, claimed that that wasn’t true, and the spring could be removed from such scopesights without danger of anything bad happening.

Anyone know for sure?




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 40484 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Master of one hand
pistol shooting
Picture of Hamden106
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Back when I was shooting NRA Outdoor Smallbore Prone, I was told to keep the Lyman SuperTarget Spot spring set against the front ring mount. Reason I believe is to keep the front ring stable on the tube as the tube sits in the ring which is like a gimbal for adjustment at the rear mount ring.



SIGnature
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Posts: 5119 | Location: Duckburg, OR | Registered: September 01, 2001Reply With QuoteReport This Post
"Member"
Picture of cas
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quote:
Originally posted by sigfreund:
The spring helped cushion the sight from the recoil shock.


The scope slides in the mount, gun recoils, scope stays still (mostly).

Some sliding scopes have springs, some don't. I've had sliding scopes, but none with springs. My assumption was always that it was part cushion, part "stop" to limit the slide, with a partial "auto reset".


_____________________________________________________
Sliced bread, the greatest thing since the 1911.

 
Posts: 17075 | Location: 18th & Fairfax  | Registered: May 17, 2003Reply With QuoteReport This Post
Hop head
Picture of lyman
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one theory is that it helps keep the scope in the same location in the mounts, and keeps the eye relief the same for the shooter,

that is why you sometimes see a shooter w/ a scope w/o the spring pull the scope back into place before the next shot,



www.chesterfieldarmament.com
 
Posts: 7906 | Location: Beach VA,not VA Beach | Registered: July 17, 2007Reply With QuoteReport This Post
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The Unertl scopes were used by the Marines on 1903 Springfields as their sniper rifle. They were not allowed to use the springs, so after every shot the scope needed to be slid back into shooting position - ie the recoil slid the scope forward on each shot.

The spring was to do this for you. It could be adjusted for recoil manually and easily with a thumb screw.

I expect that the scope tube would need to be kept very clean and smooth (waxed?) so it would return to position as designed.

Owning several of these, they are accurate, hold zero and rather simple to use.

The current American Rifleman magazine has an article on these scopes.

I believe the article says something about it, but the military, in their great efficiency, did a review of the scopes available at the time (Weaver, Warner and Swasey, Unertl, maybe others). They decided the best available to be the Unertl. Guess they figured it to be rugged enough.

One I own has a three digit serial number. Being the company was incorporated in 1935, it may be that old. It still functions perfectly.
 
Posts: 1587 | Location: south central Pennsylvania | Registered: November 05, 2008Reply With QuoteReport This Post
Freethinker
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Thanks, Chris42.
I did read the American Rifleman article.

I am now curious, though, why the scopes needed to be able to slide in their mounts.

As I mentioned above, one source claims that it was because the recoil could cause the lens elements that were glued together with the adhesives of the time to separate. Another source, however, said that was not true and there would be no damage to the lenses if the scope didn’t slide. And that would seem to be supported by the fact that not all scopesights of the era were designed to slide in their mounts.

The AR article and many of the histories I’ve read about military sniping mentioned the Winchester A5 and the Lyman 5A scopes that predated the Unertl by many years. Those scopesights fixed the tube in place and evidently weren’t destroyed by the rifle’s recoil. And because my original question about the spring was answered, I’ll ask the more fundamental question: What was the purpose/advantage of a scope that slid forward when the gun was fired rather than being fixed in position?




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 40484 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
"Member"
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Well one thing... less chance of joining the "half moon club". Big Grin



The scope doesn't slide forward. The gun slides rearward. Smile


_____________________________________________________
Sliced bread, the greatest thing since the 1911.

 
Posts: 17075 | Location: 18th & Fairfax  | Registered: May 17, 2003Reply With QuoteReport This Post
Freethinker
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Ummm …. Unless I’m shooting from something like a benchrest, I don’t want my rifles sliding anywhere. Wink




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 40484 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Hop head
Picture of lyman
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quote:
Originally posted by sigfreund:
Thanks, Chris42.
I did read the American Rifleman article.

I am now curious, though, why the scopes needed to be able to slide in their mounts.

As I mentioned above, one source claims that it was because the recoil could cause the lens elements that were glued together with the adhesives of the time to separate. Another source, however, said that was not true and there would be no damage to the lenses if the scope didn’t slide. And that would seem to be supported by the fact that not all scopesights of the era were designed to slide in their mounts.

The AR article and many of the histories I’ve read about military sniping mentioned the Winchester A5 and the Lyman 5A scopes that predated the Unertl by many years. Those scopesights fixed the tube in place and evidently weren’t destroyed by the rifle’s recoil. And because my original question about the spring was answered, I’ll ask the more fundamental question: What was the purpose/advantage of a scope that slid forward when the gun was fired rather than being fixed in position?



the glue used on the older scopes was made from cattle, (IIRC, some joint parts,, ) and was very very good , as far as adhesives go, and very clear,

recoil affecting them was not anything I ever heard, but did learn that time and storage can affect the glue (mostly delamination around the edges)

I've read elsewhere that the spring was not favored by anyone but Smallbore shooters (Unertl is considered the best, but an older (now RIP) smallbore guy I knew said the Lyman Target Spot, and Super Target Spots were almost as good and lighter (makes a difference he said when prone w/ a heavy SB rifle on your elbow)

the scope itself, when the gun was fired, did not move as much as the rifle,
theory I have read in the past says the rifle recoils, it and the shooter move back (even if just a bit) and the scope stays relatively in the same position (as in not move forward,, maybe just a hair back, but not as far back as the rifle, )

so it needs to be pulled , and some say twisted just a bit, back into position, (not sure why the twist, since there is a rib (Pope Rib is the term, I think,,) that rides in the front mount to keep it from twisting

keep in mind, the mounts (rear, where the adjustments are) are not exactly fragile, but do need to be kept clean to work properly, (dust/grit will wear one out over time)

I have springs on most (if not all) of mine, and rarely set them, but the majority of mine are for small bore rifles,


FWIW, Unertl, (considered the best) also made short hunting scopes with 2 pc external adjustable rings, without a spring,
and his sight tubes did not have a spring either,
(they later made standard looking (by today's style) hunting scopes, as well as a 10X scope for the Marines in the 70's


the history behind the scopes is interesting, starting with the Winchester which became the Lyman,
Belding & Mull came out about the same time (heavier and a bit bulkier than the A5/5A, )
then Unertl/Fecker/Litschert/Davis ,, maybe forgetting one or 3,,,,

Baush & Lomb, Redield, and Tasco made a more modern version as well, which are very nice scopes, with springs until the internal adjustment scopes got better



www.chesterfieldarmament.com
 
Posts: 7906 | Location: Beach VA,not VA Beach | Registered: July 17, 2007Reply With QuoteReport This Post
half-genius,
half-wit
posted Hide Post
Here's a little video of my BSA International MkII with its custom stock and Tasco T707 x18 scope with spring.

https://www.youtube.com/watch?v=kv5ZVEmrFOY

It's locked up on this .22, but I hafta say that it's a heavy ol' beast, that scope, and having it flapping around on top of a centre-fire like a .30-06 could not have been fun. In Vietnam, the USMC, for whom Unertl made the x8 - now a VERY rare collectors' item by itself - used to remove the springs because they got tangled up in the landscape. I have a x18 2" Varmint Unertl on my other left-hand BSA, also with the slide locked out.
 
Posts: 9705 | Location: UK, OR, ONT | Registered: July 10, 2003Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
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Thanks to both of you for your responses, and especially that tidbit about the glue used with the lenses of older scopes. Do you know how long that animal glue was used in scopes?

tac, that video was what originally prompted me to start this thread. Smile




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 40484 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
half-genius,
half-wit
posted Hide Post
quote:
Originally posted by sigfreund:
Thanks to both of you for your responses, and especially that tidbit about the glue used with the lenses of older scopes. Do you know how long that animal glue was used in scopes?

tac, that video was what originally prompted me to start this thread. Smile


It is my understanding, based on information from my my pal Chris with over fifty years of repairing binoculars and other optics in the military and Coast Guard, that the material used to secure lenses in place is actually a concoction called Canada balsam, and has nothing to do with animals, being a natural resin gum.

Please read -

Due to its high optical quality and the similarity of its refractive index to that of crown glass (n = 1.55), purified and filtered Canada balsam was traditionally used in optics as an invisible-when-dry glue for glass, such as lens elements. Other optical elements can be cemented with Canada balsam, such as two prisms bonded to form a beam splitter. Balsam was phased out as an optical adhesive during World War II, in favour of polyester, epoxy, and urethane-based adhesives. In modern optical manufacturing, UV-cured epoxies are often used to bond lens elements.

Canada balsam was also commonly used for making permanent microscope slides. From about 1830 molten Canada balsam was used for microscope slides, then Canada balsam in solution was introduced in 1843, becoming popular in the 1850s. In biology, for example, it can be used to conserve microscopic samples by sandwiching the sample between a microscope slide and a glass coverslip, using Canada balsam to glue the arrangement together and enclose the sample to conserve it. Xylene balsam, Canada balsam dissolved in xylene, is also used for preparing slide mounts. Some workers prefer terpene resin for slide mounts, as it is both less acidic and cheaper than balsam. Synthetic resins have largely replaced organic balsams for such applications.

Another important application of Canada balsam is in the construction of the Nicol prism. A Nicol prism consists of a calcite crystal cut into two halves. Canada balsam is placed between the two layers. Calcite is an anisotropic crystal and has different refractive indices for rays polarized along directions parallel and perpendicular to its optic axis. These rays with differing refractive indices are known as the ordinary and extraordinary rays. The refractive index for Canada balsam is in between the refractive index for the ordinary and extraordinary rays. Hence the ordinary ray will be totally internally reflected. The emergent ray will be linearly polarized, and traditionally this has been one of the popular ways of producing polarized light.

Some other uses (traditional and current) include:

in geology, it is used as a common thin section cement and glue and for refractive-index studies and tests, such as the Becke line test;
to fix scratches in glass (car glass, for instance) as invisibly as possible;
in oil painting, to achieve glow and facilitate fusion;
in Buckley's cough syrup.
 
Posts: 9705 | Location: UK, OR, ONT | Registered: July 10, 2003Reply With QuoteReport This Post
half-genius,
half-wit
posted Hide Post
quote:
Originally posted by sigfreund:
tac, that video was what originally prompted me to start this thread. Smile


Apologies. Do you want me to pull my input?

Quite happy to do so, if people are getting confused or offended.
 
Posts: 9705 | Location: UK, OR, ONT | Registered: July 10, 2003Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
posted Hide Post
quote:
Originally posted by tacfoley:
Apologies. Do you want me to pull my input.


Of course not. I was merely trying to give you credit for the information you provided elsewhere, and which I didn't detail at the time. Smile

And thanks for that information about Canada balsam that brings back a memory from my youth.

When I was in high school and tasked with developing a science project for class, I hit upon the idea of making a set of microscope specimens and when I asked my father for a recommendation about what adhesive to use to attach the cover slips, he said that Canada balsam was the usual method. (Why such things stick in my memory when almost everything else from that era is long gone, I don’t know.) But since we had no way of hoping to find that product in France where he was stationed at the time, I ended up using plastic model cement. I didn’t impress the teacher with the results, but at least I turned something in and didn’t get an F for the project. (I loved science classes, but hated science “projects.”)




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 40484 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Hop head
Picture of lyman
posted Hide Post
quote:
Originally posted by tacfoley:
quote:
Originally posted by sigfreund:
Thanks to both of you for your responses, and especially that tidbit about the glue used with the lenses of older scopes. Do you know how long that animal glue was used in scopes?

tac, that video was what originally prompted me to start this thread. Smile


It is my understanding, based on information from my my pal Chris with over fifty years of repairing binoculars and other optics in the military and Coast Guard, that the material used to secure lenses in place is actually a concoction called Canada balsam, and has nothing to do with animals, being a natural resin gum.

Please read -

Due to its high optical quality and the similarity of its refractive index to that of crown glass (n = 1.55), purified and filtered Canada balsam was traditionally used in optics as an invisible-when-dry glue for glass, such as lens elements. Other optical elements can be cemented with Canada balsam, such as two prisms bonded to form a beam splitter. Balsam was phased out as an optical adhesive during World War II, in favour of polyester, epoxy, and urethane-based adhesives. In modern optical manufacturing, UV-cured epoxies are often used to bond lens elements.

Canada balsam was also commonly used for making permanent microscope slides. From about 1830 molten Canada balsam was used for microscope slides, then Canada balsam in solution was introduced in 1843, becoming popular in the 1850s. In biology, for example, it can be used to conserve microscopic samples by sandwiching the sample between a microscope slide and a glass coverslip, using Canada balsam to glue the arrangement together and enclose the sample to conserve it. Xylene balsam, Canada balsam dissolved in xylene, is also used for preparing slide mounts. Some workers prefer terpene resin for slide mounts, as it is both less acidic and cheaper than balsam. Synthetic resins have largely replaced organic balsams for such applications.

Another important application of Canada balsam is in the construction of the Nicol prism. A Nicol prism consists of a calcite crystal cut into two halves. Canada balsam is placed between the two layers. Calcite is an anisotropic crystal and has different refractive indices for rays polarized along directions parallel and perpendicular to its optic axis. These rays with differing refractive indices are known as the ordinary and extraordinary rays. The refractive index for Canada balsam is in between the refractive index for the ordinary and extraordinary rays. Hence the ordinary ray will be totally internally reflected. The emergent ray will be linearly polarized, and traditionally this has been one of the popular ways of producing polarized light.

Some other uses (traditional and current) include:

in geology, it is used as a common thin section cement and glue and for refractive-index studies and tests, such as the Becke line test;
to fix scratches in glass (car glass, for instance) as invisibly as possible;
in oil painting, to achieve glow and facilitate fusion;
in Buckley's cough syrup.



interesting,

I had heard of the glue from some animal from a guy in NJ that is supposedly a guru on those type scopes,

a customer that bought a couple from me had them sent to this guy, and he gave me a rundown on each as far as what the lenses were ,


sounds like he was full of another animal product,

thanks for the info



www.chesterfieldarmament.com
 
Posts: 7906 | Location: Beach VA,not VA Beach | Registered: July 17, 2007Reply With QuoteReport This Post
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