B-Square 11-mm Bubble Level Dovetail

I use these on my PCP airguns. First to set them up. Then I permanently leave them on. Canting is a real accuracy killer! Mine is set up so at a glance I can check for level. Shooting here in the hills of TN its easy to be fooled. Making clean head shots is key to airgun hunting. This bit of kit makes a big difference. While I didn't notice any loose insert over the 9 months or so I have had it in the field. I did after reading reviews here checked mine as I just ordered another one. Sure enough it slid right out. A dab of super glue was all it needed. No worries. New one will be here today. Will inspect it and fix as needed. Worth the small inconvenience to me.

The 11mm bubble vial level looks and feels well made, however, that is where it ends. In use, the vial will fall out. You will have to glue it in if you keep it. Second, and this is the main reason I returned it, once mounted to your 11mm scope rail (my use was a CZ 452 UL) the bubble is not accurate. Before mounting I tested its centering on my Empire 2 foot level. It measured good. So I thought, no issues, however once securely mounted on the rail, it would not show level against other magnetic levels I was using on the rail. You could visually see the cant in the rifle looking down the rail. Either my rail was the issue or the mounting system on the bubble vial. Using other magnetic level bubbles that I have (which measured good against my 2 foot level) they were able to show level on the top base of the rail when attached and visually looked level to my eye. Still could be user error on my part, but if it is, then maybe additional instructions (there are none) should be included.

I started using these to level scopes. Now I leave them on the rifles for match shoots. It really helps to train myself to keep the rifle upright. After a while I can remove the level and I will still keep the rifle upright. Simple and inexpensive solution. Cheap enough to buy enough for multiple guns.

Overall, I'm pretty happy with this level. I initially use it to level the reticle on my scope and afterwards, use it to ensure I'm not canting the gun. It is a well-made little device. It does have a couple of issues in my opinion: The moving "clamp" part tends to bind on the screw when you tighten it down. This means you have to work a bit harder than you should have to, to ensure the level is properly clamped to the rails on the receiver. Also, the clamping screw uses a Torx-type head rather than a standard hex-socket. Why? Yes, they provide the wrench, but I have multiple sets of allen (hex) wrenches stashed on my work-bench, shooting bench, etc. With the special fastener, I have to hunt down the wrench. Yes, I could replace the screw, and you don't generally remove the level often, but why the complication?

I bought this for long range shooting so I planned on having it permanently attached to my rifle. I mounted it on the top rail no problem. But as soon as I carried across the room to shoot it I looked down to check level and the bubble tube was gone. Searched the room finally found it, thank goodness I hadn't been outside, found the tube put it back in but just tipping the rifle to the side it falls out. Looked for a place for a missing O ring or snap, none found. I don't know if they made it to be able to change the tube or it just never got fastened in.. Either way as it is now its useless to me. I almost bought the Hawke model since I have a Hawke scope but the B square was Amazon prime so I went with it. Mistake.

Bought this for my HW100, but it cannot fit! the action is too "square" near the scope rail and prevent the bubble from fitting flush on the rail. fit good on my HW85 though, since the action is round. good build quality otherwise.

Yes, the little vial does drop out, but just super glue it back in. It's great for making sure a scope level (the ones that attach to the scope) is indeed level to the rail, but I wouldn't recommend leaving this on your rifle, as you may lose the vial eventually.

Works just fine. Did not experience any issues with dovetail, screw or spirit level. I use primarily during scope setup but could be used as an anti-cant device. Seems to check out fine when I compare to other methods of leveling receiver. Pretty good value compared with alternatives.