The thrust ratio is important to get right while using a caulking gun because it measures the amount of force applied to the piston every time you pull the trigger. This ratio depends on the thickness of the material in a proportional form. Caulking guns are available with ratios as low as 3:1 and as high as 18:1, which is the starting point for polyurethanes and construction-related adhesives. If you aim to get some DIY projects done around the house, a caulking gun with the average ratios of 5:1 to 12:1 should be ideal.