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Alstone · Moderator & Site Supporter

I have been going to get a bubble level for my QB Custom but I think the price charged for them is totally ridiculous, as with most airgun accessories. Anyway I decided to make my own.

To start with I bought a cheap spirit level the type fitted to caravans/trailers for levelling up when parked, this was only about $3.00, the rest I made out of steel but it could easily be built from plastic, all you need is a piece of plastic tube another piece of plastic to make the base and glue them together, next crack open the spirit level and remove the bubble and glue it into the tube, make a couple of end plugs and your finished.

To fix to your gun you can either screw it to the top of a scope mount as I have or use double sided tape, the type used on car mirror’s, a coat of black paint and your done.

Al

SMP · Silver Status Member

NZ Shooter · Suspended

Hi, I was just wondering exactly how any bubble level is set correctly on a gun. What is used as a reference for a "perfectly upright" rifle? Surely if the gun is not perfectly perpendicular to sea level - when attaching a bubble level - wouldn't that negate the purpose of even having one???
And if the scope crosshairs are used as reference for bubblelevel-mounting,would you not be able to simply use said crosshairs for trueing up your gun while shooting? All that being said, if you mount a bubblelevel on your scope, then discover the scope crosshairs are 'canting' to one side ( but your bubble is in the middle ) which of these is not level ; gun, scope , or bubble ? Hmmmmm Rolling Eyes

Alstone · Moderator & Site Supporter

radar · Silver Status Member

NZ Shooter · Suspended

Cool I forgot the plumbob trick Laughing

How though, can one align the rifle dead upright? also too, it does sound as if the scopes vertical crosshair is the vertical reference. so how come there's a need for a bubble, - if the shooter is so confident the crosshairs are square to the bore? (upright and perpendicular to sea-level....)

SMP · Silver Status Member

SMP · Silver Status Member

alrighty...now that I'm a bit more composed Smile

Levels are not just used to keep a rifle "level" Often in competitive shooting rifles are shot with a purposeful cant. the bubble can be set for the cant and then used as a reference for repeatability. This allows the head to be positioned upright, which improves balance/stability and the rifle is then tilted to the head.

So handy is this in fact it is not allowed in ISSF 10m class

NZ Shooter · Suspended

That was funny.... cheers for answers. I have read (on this site I believe) that having a slightly tilted air rifle while firing, can affect the POI. Is this true? the way i see it, the bore is always inline with the crosshairs, no matter the orientation of the rifle. If indeed this is fact, and a tilt can ruin the accuracy, how so??cheers Mr. Green

SMP · Silver Status Member

If the rifle is sighted when it is straight up and down then fired with a cant the POI will be affected. This happens because the trajectory curve always follows gravity.

When you sight in a rifle the line of sight and the line of bore are on an intersecting angle. say the intersection is at 10m. You fire the gun and the pellet crosses the line of sight going upwards at ten meters then because of gravity it crosses the line of sight again at about 30m going downwards

If you cant to the left now gravity is acting on the pellet to pull it left of the line of sight instead parallel to it.

Canting is really only effective in the fixed distances of target shooting

NZ Shooter · Suspended

The more I think about it,the more it makes sense. Smile

Slavia · Moderator

I use bubble levels on many of my guns, with various fixtures for mounting. My favorite on scoped guns is to cut down a scope ring (now is the time to buy, since Walmart usually has them on clearance about this time of year.) Walmart's cheap torpedo level is only a few bucks and yields three vials. I have found that if you paint, it pays to scrape the paint from the ends of the vial. Light entering from the end makes the bubble more visible. If the level is close to your eye (as on a scope) a couple of dots of flourescent orange paint with a toothpick help. Even if you can't exactly focus on the level, the dots will let you center the bubble.

A spirit level seems to make a difference for me at ranges of 25 yards and beyond, but if the target is very small they also help close up. Like shooting at toothpicks in my basement - or the 0.04" center ring of a 10 meter target. SMP is right about cant and fixed ranges (like the 10m range in my basement, or that fence where you always put your tin cans). The bubble doesn't have to be centered in those cases - you just have to put it in the same spot each time.

To make the level agree with the reticle I also use Alstone's plumb line method. Or sometimes a power pole or the side of a building, if I have measured them and know that they're plumb. Some people rest another level on the elevation screw, but I don't trust that the turrets are always manufactured in alignment with the reticle. I also don't trust my own perception - it seems like shooting position can distort what I think is vertical. Several times I've been at the range shooting from a bench, and it seemed like the bubble had slipped out of alignment. After standing up and sighting on an object I knew to be plumb it was fine.

To align the reticle to the gun, the common wisdom is to have the vertical crosshair point downward to the center of the compression tube. Finding a reference point for the center and mentally extending the crosshair line downward has always been difficult for me, so I use another level on the action. On break-barrels I use the breech block side as a reference, with a level that I modified to fit against the block:

oddtodd · Silver Status Member

That's pretty slick tool. If I was in competiton I would have to get into all of that, but all I shoot is rabbits, squirrel, starlings, and english sparrows. I wish I had time to set the bubble up but I have to take the shot the moment I have it. Even if I miss I tried. lol I usually use a level and a windowsill to set my horizontal crosshair. Just make sure the windowsill is level first.

WhitleyStu · Veteran Member

The easy way for $19 ...