I normally find a vertical straight edge in the house -- door jamb, piece of furniture, wall corner -- and verify it's vertical using a carpenter's level.

Once the rifle and scope are also leveled, the straight edge tells me if the reticle is correct.

I'm not the expert, but this works for me. It's similar to using a plumb line.

I purchased a lot of laser boresighting and scope setup kits. SiteLite laser makes one of the good kits, and they give you a thick paper target with a leveling bubble attached to the target. Hang this on the wall around 50 ft from the barrel of the weapon, and the vertical is as good as you get, short of using a $500 3-axis laser leveling tool from Milwaukee.

https://sitelite-lasers.com/product_SRL100.html

They also provide a free ballistics program from Concept Development Corporation. This is one of the few programs that can be used to figure out how many minutes of arc are required to elevate the bore from level, to zero a weapon at a given range. For example, on a rifle with a scope-to-bore distance of 1.5", you will need to adjust your scope to make the bore point +13.9 moa to nail a target at 100 yd, using 36 grain CCI mini-mag .22LR ammo.

Cool tool tho.

I'm cheap. I tape a string with a fishing weight from the ceiling for my vertical line. Learned this from that Alaskan show, meet the Browns... I think that's what it is called. Gravity is free. Ask my tummy

And I use magnetic bubble levels on the rifle.

But what I have found out is that as long as the 2 levels match up (one on a pic rail where your scope is being mounted and 1 on the top cap of your elevation turret) it will be leveled. This works as long as both bubble levels are "calibrated" the same from the get go. It doesnt matter if the bubble is not centered or touching the center line with the edge of the bubble. As long as both are in the same place ..then when you turn your rifle to make the bubble go into the 2 marks of the level then the other (rifle or turret) level will follow. I usually make the bubble edge touch 1 of the lines to make it easier.

Forgot to mention. This works with quality scopes. If you plan on using a 20 dollar scope then the qc on the reticle might just be way off. I like to stick to etched reticles instead of wire. More chance to be shittt from the get go

There's another Vertical Reticle Tool.  Real close looking.

However, this one uses a small bubble level to put on the top of the scope cap.


https://tier-one-usa.com/collections/optic-levellers-1/products/scopeset-scope-levelling-kit

I have this one.  I ended up using it to verify the level of the scope on my .308 Rem 700.  Confirmed that how I leveled the scope using plumb bob at the range was good.  That said, it will make leveling the scope at home much easier and then verify on the range.  Much rather do stuff like that in the comforts of home.  That and I also have scope bases and chassis that also have bubble levels and want to try to set those up properly as well.

https://www.realavid.com/product/level-right-pro/

Drck1000 -  hey, I got that one too.  I always try to find a better one.  Use these tools one-at-a-time on the rifle to verify and re-verify the accuracy.

Leupold  makes 1 that attaches to just after the dials.

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