Continuing with the overview of the mounts I have on hand...
To date, I have talked abotu a good number of different single piece mounts. I really liked Reptilia AUS and Area 419 mounts. Badger Unimount is probably my choice if you want to be under $200. Someone told me they are discontinued, but there are still a few out there (OpticsPlanet, Inc - 4355). Seekins MXM and its Vortex equivalent have been very solid in my practice. There are a couple of simple inexpensive mounts out there from Brownells and SwampFox that work surprisingly well, but I have to admit I have not tried them with precision scopes. Going back to the higher end of things, I have a 34mm Era-tac Adjustable slope mount that will be a subejct of a future article. I also have an M-Brace mount from ARC. It is generally a good mount, but I naturally have a couple of reservations. I will cover that in the future as well. Another mount that I have not talked about a lot is Wanre Precision MSR. I am reasonably happy with it though on balance, I think I like Reptilia a little more.
My original favourite was the Aadmount and in terms of the clamp design I think it is still the best (Seekins is somewhat similar conceptually, I think). Unfortunately, they are not made any more. I hope they will come back eventually.
If there are other mounts out there I should be looking at, please let me know. Once I am done with these, I'll be ready to explore something else.
The subject of this article is Griffin's SPRM mount. I am sure the name of the mount is not accidental. The version I have is the one specifically intended for the S&B Ultra Short 5-20x50. That scope does not have much of a maintube to work with and the original version had the illumination knob right in front of the eyepiece. Normally, SPRM mount has six screws on both rings. This version has six screws up front and four in the back because there was not enough space. I no longer have the S&B I got the mount for, but the very short March 1.5-15x42 is back here, so I used the mildly pornographic SPRM mount with it.
The plan is to put this scope onto my 8.6Blackout Fix. It should be a good match there. For all the subsonic shooting I do, it would be better to have a mount with slope, but it will do in the short term. March has 40mrad of adjsutment and a tree reticle, so it will take my subsonic 8.6 loads a bit past 500 yards.
Eventually, I'll replace it with something lighter. For this application, I am not hugely concnerned with accessory mounting.
The SPRM mount is, by modern standards, comparatively inexpensive at $200 for the base mount https://bit.ly/4aF7jpr
It is machined out of 6061 aluminum. All the different cross sections seem fairly stiff. In terms of ring half stiffness, it is not bad. The ring gaps on two sides are offset in order to allow additional accessory mounting points. That means on one side the screws are pointing up and on the other, they are pointing down. It is a little bit of a pain in the ass, since there is some interference with the screws on the clamp.
It is generally a somewhat awkward mount to set up. The picatinny clamp is a long sinle piece, which I do not like. There are four cross screws that also serve as recoil lugs. The clamp screws are not recessed, which is also a somewhat odd decision. You have to be a little careful with how you tighten the clamp or you will have a wondering zero.
The accessory mounting depends on the friction between the accessory rail and the mounting area. Two 8-40 screws hold the accessory plates in place. It is not a great way to go. You want interface geometry to define all the positoning, not surface friction. There are quite a few different availabel itnerface plates. I have the offset picatinny and RMR plates.They work well enough until they shake themselves loose. A little sleeve-type (green?) loctite would probably help keep them in place. In other words, I do not think it is the cleverest mounting interface in the world, but that is resolvable. Area 419 and M-Brace use much better approaches, but cost a lot more.
Despite being fairly solid, the mount is not terribly heavy. Still, I can shave off three ounces if I switch to the Reptilia or something like that.
If you pay attention and tighten everythign carefully and evenly (and with a torque wrench), it seems to stay zeroed. It does not return to zero all that great in my experience and I suspect it has something to do with the geometry of the clamping bar. Still, once set up, it stays that way. All fasteners are T15 which makes for reasonable convenience.
I am also not crazy about six screw rings. Unless you are preparing for some truly massive recoil, it is not clear to me what the reason behind that is. This is not unique to Griffin, of course.
All in all, it is a serviceable mount, but not my top choice. The appeal is that you get a mount set up for accessory mounting for comparatively less money than a lot of the other brands out there. The accessory mounting interface, however, is a little suspect.
