I recently purchased a new scope for my [classified] and wanted to get it zeroed in soon after it was installed. Many people that have scoped firearms utilize a nifty little tool called a laser boresighter to help them at least get their first shot at the range on paper and as close to the bullseye as possible while burning through as little ammo as possible. Years ago I picked up a rather inexpensive unit from Bushnell, part number 74-0100C, but the thing just never worked quite the way I wanted it to. It has a very flimsy on-off switch that makes it very frustrating to use. Sometimes you get the laser and sometimes you don’t which makes it really aggravating when one is trying to get several guns dialed in at once. Previously I just dealt with it not wanting to help the economy out by buying a new unit.
Since it had been awhile since I used the boresighter I decided to drop in some new batteries and see if I could come up with a solution to fix the mickey mouse switch in the process. I removed the battery compartment, which also contains the on-off switch, to see if I could make this darn thing finally work properly.
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Turns out it was much easier than I thought!
After the battery compartment is removed you will see a small spring in the head of the main unit.
When the switch is rotated to off it pushes the batteries ever so slightly towards the laser compartment at the head of the unit disengaging the power and shutting off the light. When the switch is turned on the spring is supposed to push the batteries back towards the probe end of the main unit completing the electrical circuit thus providing the needed laser light. The on-off setup Bushnell uses with this specific model doesn’t work for spit and the light often flickers or you have to monkey around with the switch until you get a steady beam. Aggravating but hey the thing only runs about 25 bones so I have just dealt with it up til now.
The solution? Take a tiny conductive (non aluminum/plastic) screw with the flattest head you can find and grind the threads down until it has about a 1/8 inch length. If you can’t find a flat head screw just grind the dome down until it is flat and about 1/16″ thick giving an overall length of about 3/16″. You may have to slightly adjust these measurements according to your particular unit.
Place the threaded part of the screw inside of the spring, load the batteries into the compartment (the polarity is marked on the side) and put the thing back together again. Presto, a much more solid feel and the switch works perfectly now. I highly recommend removing the battery compartment if the boresighter won’t be used for a period of time so it takes the stress off the spring and will be ready to go the next time you need to dial a gun in. My unit is beyond the warranty period however if you were to need to return yours for warranty service simply remove the screw and there is no evidence of alterations.
For those new to laser boresighters here is a great video that explains the process for getting your gun on target quickly.