Depends on the size of the jar and the size of the pickle(s) and the force exerted... In regard to canning pickles, I’ve learned a few tricks to help keep my jars crack-free, so I think I can help you out.
The quick answer is, what’s happening to cause your jars to break is called thermal shock. Basically, the glass is being asked to accommodate a too-rapid temperature change.
As your jar is lowered into boiling water, the glass attempts to expand slightly. When this expansion happens unevenly, stress builds up, and the brittle glass simply can’t take it.
Result? Cracked jars.
