The IOR Heavy-Duty, 20 moa Tapered-base

1 June 2002
By Scott Powers

I have a Remington 700 Varmint Synthetic in caliber 22-250 with a long Bausch & Lomb Elite 4000 6-24x scope. I love that rifle. It has taken its share of prairie dogs and ground hogs and its accuracy is simply outstanding. One of the things that has always bothered me however was that the scope, with only something like 36 moa of internal adjustment, has limited just how far you could reach out and touch something. Took a lot of p-dogs with hold over. But it was like dropping in artillery: Shoot, spot, adjust.

My 700P has a tapered 15 moa M1913 rail on it so I thought I would try the IOR product this time for my 700 VS, do a little scope swapping and see how it held up to the competition.

Measuring approximately 6.3 inches long, the base has 15 cross-slots and conforms to the Picatinny Optic Rail specification, Mil-STD-1913. In other words, most tactical rings like DD Ross, IOR, MWG, Badger Ordnance, and Leupold's Mk4s rings will fit as well as Weaver rings. I believe the origin of this heavy duty tactical ring system resides with the McMillan Brothers and since that time forward, they have taken the market in many forms. I do not know if the McBros had anything to do with the M1913 specs, but I have heard that they certainly came up with the grand daddy of all the tactical rings we see today.

Like IOR's flat base, the IOR 20 moa Heavy Duty Tactical base comes with hex head action screws (my only real complaint) and is finished in a black Chromate Process coating. This is said to be harder than a black oxide type of finish. Again, you will have to be the judge, as I don't understand the finer points of metal finishing. As I said in my review of the flat base, I am only knowledgeable in the denting, scratching and painting department.

IOR-Valdada, when deciding to go with a tapered Picatinny rail system of the M1913 specification, collaborated with DD Ross for the basic idea, using their knowledge in the design. This is IOR's second-generation tapered base. The first, no longer in production, was a four-slot tapered mount and this new mount is quite an improvement in terms of versatility. After the collaboration with DD Ross, IOR soon dropped its old four slot tapered base for this new and superior design. It is made by IOR in Rumania and is made of very high quality steel. The machine work on the IOR produced rail is perfect with no machining marks to be found. The mating surface is totally free of blemishes and mated up to my 700 VS as expected. Like both the DD Ross and Badger Ordnance mount, there is a Recoil lug provided in the base, which mated to the cut in the Model 700 receiver. There is also a relieved area in the base to assist clearance of ejecting cartridge cases.

This base is very similar, but not totally identical to the Badger Ordnance base. There are small detail differences and of course the IOR base is, in my view, technically a 15 moa base, not the taller 20 moa. It is represented as a 20 moa base, but that may not be the case. It's front and rear height is identical to a 15 moa base I also have so, much to my delight, I can actually get a fair cheek weld using this mount, which I cannot do with a full-out 20 moa base. There in lies one of the two downsides of all tapered bases from any manufacturer or nation. If they are tall enough, they force you to raise your head up off the stock to get a clear sight picture. Which means creating either a raised cheek rest or going to an adjustable stock. In the case of the IOR mount, that was not an issue so I will maintain until proven otherwise that it's actually a 15 moa mount like my other unit. This pleases me no end as I see little need for 20 moa taper with most of the current scopes one finds on the tactical market. This seems to be a debate among the various manufacturers and I will leave it to them. For me, I prefer and feel that 15 moa is plenty tapered for any scope I could hope to use. For instance, with a Leupold Vari-X III, Long Range M3 – with only 60 total moa of internal adjustment available -- and the IOR base, I can dial up to over 1200 yards before running out of clicks. That is more than sufficient for my needs! Yet this still allows me to keep a relatively decent cheek weld on the stock.

As in my reviews of previous mounts of this type, based on the M1913 specification, this base is rock solid. Whenever I hold one of these things I, for some reason, mentally picture driving it through a car door with a sledgehammer. I am willing to wager that the mount won't notice the door at all. Its strong and solid in a way that your average department store mounts only dream of.

The holes in the base are sized to fit 6-48 screws and the screws provided have large oversized heads. I believe the head size of the screw hole in the mount will fit a 8-40. This is a nice feature as it allows you to move the base around a bit if you are one of those unfortunate souls who has a receiver with mounting screw holes slightly off axis. It also saves you a bit of time should you choose to upgrade the screws and tap your receiver for the heavier 8-40s. Like my recent review on the IOR flat base, my one and only real nit is that the provided screws are Allen heads. I have come to prefer Torx heads for all my mounting needs. It's a small thing. I just wish every manufacturer would go the Torx route. Replacing the screws is simple enough. But means a trip to the hardware store and most do not carry Torx of this type. Many of you won't bother and even fewer will ever find a reason to remove the mount once installed. But in my position of reviewing various mounting systems I find that its typical for me to have to remove a mount more than the standard once in a "blue moon."

As I have stated in another article on a different topic; the one true downside to a tapered base from ANY manufacturer is, that in its strength lies a possible problem. Nor can you blame the mount. My one caveat before you buy any heavy-duty tapered base is that you make sure your receiver scope mounting screw holes are in alignment. These bases are generally strong enough that you will warp your receiver before you twist the base. And a warped receiver does not make for good accuracy. This comes right from a gunsmith acquaintance whose expertise lies firmly in the realm of long range accuracy. This is not a reflection on the IOR product, but you should be aware of this whenever considering the purchase of any heavy-duty scope base found on the market. Make sure you rifle is up to the base! The bases are good! But the rifles sometimes have holes drill as though by a drunken sailor.

Back to the product. The mount's finish is excellent overall and is a deep matt black with a light-dulling texture to it. There was a small area of thinning in the finish between a few cross-slots but again, for the price this bothered me not in the least. Particularly since my rifles ultimately end up painted. Even barring this fact this was barely noticeable until I held it up to the light. This mount will make an excellent addition to my VS and solve my elevation problem with room to spare. It can be had for a reasonable price, which will fit most budgets - a real plus for those who want high-end mounts but can not always afford them.

The base can be ordered direct from IOR at:

Valdada IOR Optics
P.O. Box 773122 RCR #35
Steamboat Springs, CO 80477

Or you may find it at any number of outlets both online and via catalog, including our own Sniper Country PX.


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