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SELECTABLE-APERTURE EYECUPS
By Wayne McLerran
Last update: 2/2/15

Notes:
1) Selectable-aperture eyecups come with some rear sights.  This article assumes
you already own or have decided on a rear tang sight without a selectable-aperture
eyecup.  If not, than you may be interested in the article titled
Sight Suppliers for
Black Powder Cartridge Rifles.  
2) In the following discussion “aperture” is defined the same as when discussing
optics or optical components, i.e. a hole or an opening through which light travels.

There are six suppliers that I’m aware of for selectable-aperture eyecups for black
powder cartridge rifle tang sights
.  “Hadley-style” eyecups are available from
Montana Vintage Arms (MVA), Lee Shaver Gunsmithing, Kelley Sights, Distant
Thunder and Davide Pedersoli.  MVA and Kelly offer two eyecup versions, a
standard size and a magnum or large size.  Baldwin Sights and Kelley Sights make
“Lyman-style” selectable-aperture eyecups.
















MVA Versus Lee Shaver Standard Size Hadley:















The two most common Hadley-style standard eyecups purchased are the Lee
Shaver and MVA.  I have used both.  They are well made and at first glance
appear very similar to each other.  They do suffer one disadvantage which is
discussed below under Other Considerations.  From the front the Lee Shaver and
MVA look almost identical, but a closer inspection will identify a few
differences.  As featured by several suppliers, both the Shaver and MVA have a
rubber ring around the outer edge to help protect the shooters eyes and/or glasses
due to rifle recoil, and the stock comb when the sight is folded down.  The main
differences are the layout and the size of the apertures.  The MVA standard
eyecup apertures are laid out in reverse order compared to the Shaver, which
may or may not be important to a shooter.  In other words, rotating the MVA
aperture disk clockwise decreases the diameter of the selected aperture; rotating
the Shaver aperture-disk clockwise increases the aperture diameter.  For what
it’s worth, the Shaver setup, which is common to most of the other suppliers,
seems more “natural” to me since it’s somewhat analogous to other manual
controls such as volume, speed or brightness for example, which are normally
increased by rotating clockwise.

Another difference not noted in the table is the Shaver is stamped L. SHAVER
on the front of the sight.  The MVA has no markings at all.  The Shaver has a
matt blued finish on the front and back.  The MVA has a matt blued finish on the
front and a gloss blued finish on the back.  The Shaver inside cup surface is a
little flatter (less concave) than the MVA.  The Shaver requires less effort to
rotate the aperture disk between detent positions.  Considering all of the above
and assuming both are available in the thread size you need, I would probably
give the nod to the Lee Shaver version.

Kelley, Distant Thunder & Pedersoli Standard Size Hadley:















I have not used the Kelley, Distant Thunder or Pedersoli Hadley eyecups, but did
discuss the construction and features of the Kelley Hadley with the manufacturer
Jim Kelley, and also with O’Hare Tool the manufacturer of the Distant Thunder
Hadley.  The Kelley design eliminates the problem discussed below under Other
Considerations.  The Distant Thunder does have the potential problem.

Pedersoli’s Hadley is very similar to the MVA or Lee Shaver design but has one
less aperture selection.  It has a metric M5 x 0.5 thread size to match their rear
sights.  The diameter of the eyecup is not listed on Pedersoli’s website but it's
approximately the same size as the MVA or Lee Shaver.  It also uses the back of
the adjacent aperture for the detent positions and, like the MVA standard Hadley,
rotating the aperture disk clockwise decreases the diameter of the selected
aperture.

MVA Montana Magnum & Kelley Large Size Hadley:

















I have not used the MVA Montana Magnum or Kelley large eyecups, although I
have handled and installed the MVA Magnum on a rear sight.  At 1.95” in
diameter, it is the largest of the Hadley-style designs.  It weighs a hefty 2.5oz and
features a wide selection of aperture sizes.  It has a matt blued finish on the front
and gloss blued finish on the back.  What I found interesting is the apertures are
arranged in the reverse order of MVA’s standard size Hadley.  The size may be
too overwhelming for some shooters as it was for me.  Also, the weight can be an
issue due to rifle recoil, especially if the rear sight staff is tight and does not rotate
forward out of detent.  Here’s one shooter’s comment, “On my .45-90, it's like
being hit in the face repeatedly with a ball peen hammer when the trigger is pulled;
a real flinch training machine.  Mine has probably been used less than 10 rounds
before I got smart and removed it.”  By the way, it does not have the problem
discussed below in other considerations.

The Kelley large Hadley is described very well in the table and is a “petite”
design when compared to the very large MVA Magnum.  As noted in the
discussion on the standard size Hadley’s, the Kelley also does not have the
problem discussed below in Other Considerations.

Steve Baldwin & Kelley Lyman-Style:
















If you like the looks of a traditional style eyecup and the smaller size is visually
pleasing, the Lyman-style may be the ideal solution as long as your rear sight will
accept 10-32 threads.  The main difference between the Baldwin and Kelley is the
finish.  The Baldwin has a matt blued finish and the Kelley is color cased
hardened.  And be sure to read the following discussion that highlights one key
benefit to the Lyman-style design.

I should note that at the time of this writing Buffalo Arms (BACO) does not list
the Kelley Lyman-style for sale.  Jim Kelley indicated that BACO should be
adding it soon, but until then you can order one directly from Kelly Sights.

Merit Adjustable-Aperture Eye Discs

















A discussion on multiple-aperture eyecups would not be complete without
touching on the Merit eye disc.  Merit Corp. offers several models of iris-type
adjustable aperture eye discs, the most popular being the #3 Adjustable Master
Aperture eye disc with the 1.5” neoprene light shield.  
As of this writing, due to
the nontraditional design, they are not approved for NRA sanctioned BPCR
silhouette matches.
 I do understand the Merit discs are permitted in BPCR long
range target matches.  The aperture diameter is continuously adjustable from
.022” to .125” and it’s available with three shank lengths and three thread sizes:  
7/32-40 (12-40), 10-32, 10-40.  The disc with the light shield is available directly
from Merit ($66.00) or from Midway USA ($60.99).

Other Considerations:
If you’re struggling with making a decision between a Hadley-style or Lyman-style
eyecup, it’s obvious that one advantage of the Hadley-style is the larger selection
of aperture sizes.  But the Lyman-style and Kelley Hadley designs have an
advantage over the Lee Shaver, Distant Thunder and MVA's standard Hadley’s
that may not be obvious.  The problem with the design of some of the Hadley
eyecups is the detent ball is in the same radius as the apertures and snaps into the
back of the adjacent unselected aperture for the detent positions.  Therefore, if the
detent ball is lubricated, oil can transfer to the apertures, making them a dust/lint
magnet.  Although limited in aperture selection, the Lyman-style design avoids the
problem as does the Kelley Hadley design and the MVA Montana Magnum.  Look
closely at the photos of the Hadley’s and you’ll spot the reflection of the detent
ball.  The “Also Used for Detent” column in the above table indicates which
eyecup is at risk.

Another consideration and a possible negative of the Hadley-style can occur when
loosening the eyecup to adjust the elevation setting.  Depending on the location of
the aperture disk, the disk can be inadvertently and unknowingly rotated to a
different aperture.  The Lyman-style prevents this from happening.

During your selection process, keep in mind that the threaded shank of the eyecup
must match the rear sight threads or the threads in the elevator of the rear sight
staff. If you already have a rear sight and know the thread size the information in
the following chart is most likely not important.  As noted, the most common
thread size is 10-32, but it’s certainly not a standard.  Kurt Schinze provided
much of the data.  I added a few details.  But you know what they say about
assumptions, so don’t assume the thread sizes listed are accurate.  Double check
the threads in your sight or contact the sight supplier prior to ordering an eyecup.  



























Manufacturers & Suppliers:

Baldwin Sights (Steve Baldwin)
P.O. Box 971, Jones, OK 73049
Phone: (405) 399-2875
www.baldwin-sights.com
A well-known high-quality supplier of BPCR sights

Brownells Inc.
200 South Front Street, Montezuma, Iowa 50171
Phone: (800) 741-0015
http://www.brownells.com/
Brownells sells the Davide Pedersoli Hadley-style adjustable eyecup.

Buffalo Arms Co. (BACO)
600 Vermeer Court, Ponderay, ID 83852
Phone: (208) 263-6953
www.buffaloarms.com
Buffalo Arms is the leading supplier of products for the BPCR reloader and
shooter.  BACO sells the following brand of soule-type sights and accessories:
Baldwin, Kelley, Lee Shaver and Red River.

Distant Thunder Shooting Products
O’Hare Tool, Inc., W8515 County Road N, PO Box 138, Niagara, WI 54151
Phone: (715) 251-3839
http://www.distantthunderbpcr.com/DTPages/DTProduct.htm
High-quality sights for BPCRs.

Kelley Sights
High-quality sights for BPCRs.  To check out the Kelley sight offerings go to
www.kelleysights.com/ or Buffalo Arms Co. (www.buffaloarms.com).  Kelley
sights are available for purchase from Buffalo Arms.

Lee Shaver Gunsmithing
P.O. Box 570, 1020 Broadway, Lamar, MO 64759
Phone: (417) 682-3330
www.leeshavergunsmithing.com
leeshaver74@yahoo.com
Lee supplies his own line of sights and accessories.  Contact Lee directly or go
to Buffalo Arms Co. (
www.buffaloarms.com) for his products.

Merit Corporation
P.O. Box 9044, Schenectady, NY 12309
Phone: (518) 346-1420
www.meritcorporation.com/products.html
Merit manufactures adjustable aperture discs for shooting glasses and rifle sights.  
The Merit #3 Adjustable Master Aperture eye disc is also available from Midway
USA (
www.midwayusa.com).

Midway USA
Customer Service, 5875 West Van Horn Tavern Rd., Columbia, MO 65203
Phone: (800) 243-3220
www.midwayusa.com
Midway sells the Merit #3 Adjustable Master Aperture eye disc.

Montana Vintage Arms (MVA)
61 Andrea Drive, Belgrade, MT 59714
Daytime phone: (406) 388-4027, Evening phone: (406) 388-3405
www.montanavintagearms.com
MVA is a well-known high-quality supplier of BPCR sights and accessories

VTI Gun Parts (Pedersoli)
P.O. Box 509, Lakeville, CT 06039
Phone: (860) 435-8068
http://www.vtigunparts.com/store/shopcontent.asp?type=home
mail@vtigunparts.com
USA based supplier of Davide Pedersoli sights, parts and accessories.


Wishing you great shooting,
Wayne