September 23, 2010
By Mike Venturino
Step back into the 1800s with this vintage-style scope.
By Mike Venturino
The external-adjustment RHO mounts fit into the barrel's front and rear sight dovetails. The rear mount is graduated for two MOA adjustment with a total elevation of 180 minutes.
Like many aging baby-boomers, my vision has deteriorated significantly over the last 20 years. That this is true with many other shooters is evidenced by the fact that in 2001 the NRA officially incorporated a special scoped class for the Black Powder Cartridge Rifle Silhouette (BPCR) game. The NRA's rules for such scopes call for them to be patterned after vintage-type telescopes from the late 1800s with external adjustment mounts.
For the past few months I've been using such a scope on one of my Shiloh Sharps rifles, and I have become an enthusiastic fan of this piece of equipment. My scope is manufactured by RHO Instrument Co. and is a copy of the Malcolm-type scope and mount system made originally for Sharps, Remington, Winchester, and other single-shot rifles of the late 19th century.
The scopes themselves measure 3/4 inch in diameter and are made from 4130 drawn steel tubing. The eyepiece and dust caps are machined from solid brass. Magnification of the scopes is 6X with a field of view at 100 yards of 10 feet. Eye relief is 41/2 inches, which allows plenty of clearance for the hefty recoil given by many of the cartridges for which these rifles are chambered. The eyepieces are adjustable for focus to an individual's eyes, but the reticles are plain crosshairs only. Currently RHO is making scopes for rifles with 30-, 32-, and 34-inch barrels, but company spokesmen have told me that models for shorter barrels are being developed.
I should stress that the telescopes are only half of this system. The external-adjustment mounts are the other half, and I must admit to being very impressed with the quality of manufacture that goes into them. The mounts fit into the dovetails machined into the rifle's barrel for front and rear sights. RHO standard size dovetails are for either C. Sharps Arms or Shiloh Rifle Manufacturing dovetail cuts, but RHO will supply sights with special dovetail dimensions given by the customer at no extra charge. The rear mount of the RHO system is graduated for two minutes of angle adjustment with a total elevation of 180 minutes. (A minute of angle is roughly one inch at 100 yards.)
The front mount can be adjusted for windage by hand via two knurled screws.
SIMPLE TO INSTALL
As for actually mounting the RHO telescope, let me say that I am one of the most mechanically challenged people on the planet, and I was able to drift the RHO mounts into my rifle's dovetails and fit the scope into them in about 20 minutes. It is not a difficult job if one has a sturdy vise. RHO even supplies a nylon punch with the system so that the mounts will not be damaged during installation.
The front mount of the RHO system is windage adjustable. Adjustment is done via knurled screws: One is backed out and the one on the other side is turned in until both are tight again. The adjustment screws are large knobs that are easily turned by hand; a screwdriver is not necessary. The front mount has a total adjustment of 36 minutes of angle, and the scale on the front of the mount is graduated in three-minute increments. All mounts and parts are machined from solid steel and then polished and blued. No stampings or castings are used in their manufacture.
REPEATABLE SIGHT SETTINGS
Using RHO's mounting system, a scope-sighted blackpowder cartridge rifle can be perfectly sighted-in at any practical range, and the sight settings are repeatable. To prove this to myself, I ran a simple test with a friend spotting for me. First I zeroed my Shiloh Sharps Model 1874 .45-70 to hit dead center at 100 yards. Then by trial and error shooting I also found my load's zero at 300 yards. (The load consisted of Lyman's 520-grain roundnose cast bullet from mold No. 457125 over 60 grains of Swiss 1 1/2 Fg blackpowder.) With the particular load I was firing, that proved to be 23 minutes of angle upward adjustment on the rear mount's Vernier scale. I have a regulation pig silhouette hanging at a surveyed 300 yards. My little test was this: I fired a shot on a 100-yard bullseye then elevated the rear mount to its 300-yard setting and fired a shot on the pig silhouette. Then I dropped the sight back to its 100-yard setting and fired another shot on the paper target. I repeated this process until five rounds had been fired at each range. I admit to being amazed at the results. The five-shot 100-yard group was a mere 1 3/4 inches, and my spotter friend said the five rounds fired on the 300-yard pig silhouette were all dead-center and formed approximately a six-inch group.
After gaining such confidence in the RHO telescope and mounting system, I've been using that particular Shiloh Sharps .45-70 as a test vehicle for some extensive load work during the past three months. By actual count I've fired over 1000 rounds of blackpowder handloads through that rifle with the scope mounted, and the system has absorbed the pounding from all those rounds with nary a hitch.
The RHO scope system was perfectly repeatable and very rugged; it withstood the firing of over 1000 .45-70 shots without a hitch.
A REMEDY FOR EYE FATIGUE
After firing literally tens of thousands of rounds through a variety of peep sights mounted on blackpowder cartridge rifles over the last couple of decades, I think I've become a fairly adequate shot with them. I've even been in the winner's circle at a few NRA-sanctioned BPCR silhouette matches. In testing loads from the bench over the last couple of years, however, I've experienced a considerable amount of eye fatigue. Specifically, my vision will remain blurry for hours after extended shooting sessions. When testing loads with peep sights, especially at my favored distance of 300 yards, I have trouble discerning if a flyer was caused by sighting error, poor trigger squeeze, or a faulty load. By using the RHO scope-equipped rifle I can now pretty much eliminate the first two factors. I now know where the crosshairs are when the rifle discharges.
Having several blackpowder cartridge rifles, I've dedicated my Shiloh to scope sights. However, RHO realizes that many shooters will only have one rifle to use in blackpowder cartridge competitions and may want to fire it both with and without optical sights and has developed a globe front sight that takes int
erchangeable inserts to fit into the front mount. The telescope can be taken off and the globe sight fitted into the front mount. When used in conjunction with a Vernier-style peep rear sight, the same rifle can then be used for iron-sight-only competitions.
The only slightly negative comment I have concerning the RHO telescope and mount system is that the optics are a bit dim. That is not a result of poor quality on the part of RHO but is simply caused by the small 3/4-inch diameter of the scope. Keep in mind that this type of scope predates those large objective bells of modern scopes by many years.
For shooters who want to use the same rifle with or without optical sights, RHO offers a globe front sight that fits into the front scope mount.
And finally this comment is for those who might consider scopes to be "unauthentic" on blackpowder cartridge rifles. I recently read in Sharps Firearms by Frank Sellers that his perusal of original Sharps factory records indicates that perhaps up to 1/4 of Sharps rifles shipped from the Hartford factory in the 1870s carried telescopic sights.
The RHO Instrument Co. telescopic sight complete with mounts costs $675. The globe front sight that fits into the front scope mount is an extra $95. For ordering information, contact RHO Instrument Co., Dept. ST, Box 1789, Point Roberts, WA 98281.