I’ve been reluctant to respond to this or any other thread concerning maximum “ethical” range. There are so many convictions out there that are formed from incorrect suppositions such as not enough energy remaining at such and such range, or the deer could die from old age and be lying on the ground before the arrow gets there, or the deer has so much more time to react to the sound of the crossbow/arrow going off - with the incorrect supposition that it will react the same at 60 yards as it would at 20 yards (WRONG!) - actually the noise helps as it tends to freeze the deer in place while the arrow passes through, and for other reasons.
Being an insatiable accuracy and long range shooter has caused me to run headlong into controversy in the crossbow community. Background: Chem/Math degree, have been thru multiple benchrest schools and days spent one on one with Tony Boyer, taught ballistics/bomb dropping/strafing in the USAF, Top Gun Graduate/Top Gun, worked with Toby Bridges on the loads for the 10 ML/ML-2, had the first 40 cal smokeless MLer, and have averaged 1,000s of shots yearly thru my crossbows primarily at 50-100 yards. Tested arrows for Tapp Nation, others. I only mention this in order to validate that I am a serious , long range crossbow shooter. Additionally, I’m an instructor in the NASP program and still hunt with traditional recurve vertical bows. I’m familiar with both sides of the street.
IMO, a very relaxed deer or even alert deer at 60-70 + yards will freeze in place at the sound of a shot. A relaxed deer will often show no reaction. Using normally a 2x8 Zeiss Duralyt/Optimizer on my BD400 and SWAT , or another Zeiss such as the parallex adj 4.5x14/Optimizer on my Aculeus 460, the higher power setting can give more information about the deer’s state-of-the-art-mind. Scope quality needs to be pretty good for longer range shooting.
I hunt agricultural areas and private land with long shooting ranges. This is different than most people’s situations.
Crossbows are like rifles: a 44 Mag carbine doesn’t have the capability of a 270 Winchester, neither does a Micro 335 Gen 2 have the capability of a Nemesis 480. This is neither good nor bad, just different. Each crossbow has its own limiting factors, strengths and weaknesses. So, the crossbow with the best matched arrows and optics are needed to reach the maximum practical range with that crossbow. The weak link usually is the hunter. It is for me. I bench shoot/test my crossbows to see their limits then work on my own skills to work towards optimally utilizing the crossbow/components.
As most of us know, in general, as limbs shorten the longer range accuracy suffers at 60-70 yards, the Micros will not match the Matrix series in accuracy. Stretch that out to 100 yards and the difference is dramatic. Same with arrow lengths but to a lesser degree.
I think with good optics, maybe 18” arrows with adequate foc, and the Micro would be good to 60, maybe 70 yards. The BD400, M380/405s are all capable of <1 1/2” 3-shot groups at 100 yards, repeatedly/consistently.
Groups tend to mysteriously open up when practicing off a tree stand rest, in the woods at a deer target place at random distances. But not greatly, especially if using good technics , a scope level, etc.
Energy loss is approximate 25% from 0-100 yards. IOWs , not a factor.
So, a long range crossbow could be useable to 100 yards (range measurement is critical) and a short range crossbow 60 might be the limit.
My personal goal is 40-70 yards. That is the range that I consider a chip shot.
This is my only hobby. My wife (of 51 years) says I’m ADHD so moderation isn’t a fault with me. I put my all into this hobby. If a person is willing, will get the right training and practice, quality equipment, use good judgement, there are “ethical” ranges beyond 30 yards.
FWIW, I’ve lost a total of 5 deer in 62 years of deer hunting,