I just got a really good safety question via email, to wit:
I was wondering if you had any information on “dry fires” and what can happen to the bow and what to look for (problems) in the riser and limbs. My granddaughter had an arrow fall off her arrow rest and then when she started to back down her fingers slipped and released the string. I looked it over really well and did not see anything wrong. I also shot it a few times and everything appeared okay. Any guidance you can supply would be greatly appreciated. Thanks.
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Ah, dry fires. You didn’t mention what kind of bow she has or what the bow’s draw weight is … ahem. (Please add pertinent information to your questions. If asking about a bow, describe it, etc. This makes it easier for me to answer to your question well.)
For those who may not know what a dry fire is, it is basically a bow being shot with no arrow on the bowstring. Since the arrow typically carries off ~75% of the energy stored in the bent bow, the bow is expected to be able to deal with the remaining 25% as a matter of course. But a dry fire leaves 100% of the energy from the drawn bow in the bow, or partly in the archer if a body parts is involved, hence the concern. The danger to the archer and potential damage of the bow make dry fires something to be eagerly avoided.
The odds are strong that no damage was had in this case. I have made more than a few dry fires in my life and never broken anything. Compound bow manufacturers have machines that will dry fire a bow, repeatedly, hundreds of times in the time-tested engineering practice of “testing to destruction.” New bow designs can survive as many as 400 consecutive dry fires with no damage to riser or limbs. The most common happening on the compound side when a dry fire occurs is the bow string or a cable can jump out of its track. I have had to “repair” any number of Genesis compounds for this occurrence. (The repair being putting the bow in a bow press and putting the string/cable back where it belongs.)
Recurve bows have different parameters. Youth bows tend to be of low draw weight and hence the forces involved are lower. But to get those draw weights low, very thin limbs are needed, so thin that they are subject to cracking or even breaking in the event of a dry fire. If the bow was a recurve bow, inspect the limbs to see if they retain their normal curvature (as well as for cracks, etc.). If you can’t remember what the limbs looked like before, compare one limb with the other. It is very unusual for both limbs to break because usually one limb breaks first which reduces the stress on the other. Make sure the bowstring is still secure in the limb tip notches and that the string is centered on the limbs. Check the limb tips for cracks, broken tip protectors, etc. If the bow looks okay, try drawing it while listening for any noises it may make. An internal crack may betray itself with a tiny “cricking” sound. If you are really unsure of the bow, put a bow case or folded towel on the floor/ground, lower the bow held by its bowstring onto this pad, and place your foot over the pivot point (where the hand goes on the bow). Then pull the bowstring up while listening carefully. No noise? Probably no problem. (I have to say probably because of the bizarre things that happen very, very infrequently.
I suspect that the admonition against dry fires began in the “all-wood bow” days and has been carried forward in time. A dry fire of a self bow has a very high probability of a broken bow. Some of these bows break during ordinary shots. But with the advent of fiberglass-reinforced limbs, outright breaks have become quite rare. (I have seen only a couple.) Most compound limbs are solid fiberglass now, as are Uukha recurve limbs. These are virtually unbreakable.
Hope this helps.