I talked a few days ago why I am so fond of the relatively inexpensive and not very high end BTC-50 clip-on from Burris. A big reason for the fondness is the mount. The original post is here.
I took a couple more pictures to better illustrate what I mean.
First of all, here is the bottom of the mount. Burris strategically placed the recoil lug all the way toward the back, so that you could have the clip-on as far forward on the upper receiver as humanly possible:
Note also that Burris' QD mount is quite robust. I do not think I have ever seen this arrangement with a stack of leaf springs with QD mounts before, but I have a couple of version of it and they do work well. While I am sort of on the record that I generally prefer normal non-QD mounts, on a clip-on that gets moved around a lot, having a QD lever is quite nice.
Here is a picture of the BTC-50 with the Burris RT-3 prismatic. Ignore the slight height mismatch. The mount came with two spacers and I think the shorter one would be better with RT-3, but I nee dto doule check. Either way, th emismatch does not really get in the way much at all. I've used that way simply because I was too lay to look for the other spacer.
Note that with the diminutive RT-3 3x prismatic, there is enough space on the top rail for a back-up iron sight (only there for illustration), RT-3 prismatic and BTC-50 clip-on. There is still enough rail space in front of the clip-on mount to potentially add an offset red dot sight if I am so inclined. The FOV of the RT-3 matches horiontal FOV of the cip-on nearly perfectly.
The rifle I am showing this on is my old 6.5Grendel that I really like for hog hunting. It is just a great general purpose rifle and I have had it for a long time. It has an old Lancer handgard on it where the aluminum handguard mounting (the thing right on the front of the receiver) is attached with permanent loctite. In order to swap it out for a more modern handguard, I would have to heat it up significantly. I am not hugely motivted to do it, simply because I have a lot of other rifles and because sometimes it is best to not try to improve what is not broken. This is the same rifle I shot that hog with last year:
That time I used SAI 1-6x24 LPVO with a Leica clip-on attached to the objective. While it worked well, I generally prefer to mount the clip-on on its own base when I can. However, since this handguard does not have a top rail, my options are limited.
Here is the same rifle, this time with a much larger prismatic: Elcan Specter OS 4x. Because of how the Elcan mount is designed (external adjustments), it takes a lot of space on the rail. Still, I have enough space to mount the BTC-50 in front of it. In this case, there is no rail space left for anything else, but I have a piggybacked RDS on the Elcan, That takes care of the redundancy issues and there are good reasons to use piggy-backed sights with Ecan Specter sights.
I left the RT-3 on a different upper in the picture to give a scale for the size comparison. These new micro prismatics are remarkably compact. RT-3 is essentially have the ength of the 4x Elcan. Now, you can't compare them optically, but the money and the size, I am really impressed with RT-3, PA's SLx Micro 3x and Vortex' Gen2 3x Spitfire. I suspect that Burris and Vortex are made by the same OEM, while PA is made in a different factory, but I am not sure. It really does not matter. They are essentially the same size, however, and FOV is very close (Burris is slightly wider) so they would all match the BTC-50 clip-on very well.
The FOV of the higher magnification Elcan is a little narrower. BTC-50 has a 400x300 image sensor, so instead of seeing 400 pixels horizontally, you are seeing 300. That's pretty workable. In terms of mounting height, they are matched nearly perfectly at right around 1.5" above the top rail.
Now that I think about it, I have a Mepro X4 here somewhere that has wider FOV than the Elcan. Perhaps I should try it as well. It is essentially a copy of the 4x ACOG with a different mounting system. It might be an even better match than the Elcan.
For the time being, I will probably keep the BTC-50 on the Grendel in front of one of the prismatics. I need to take this gun to Texas and see if it brings me luck again.
