i'm done with my crossbow experiment. killed one doe with it. boring. crossbow is clumsy and heavy to boot.
i've shot longbows and recurves for decades; used to be very good on target; never could loose a string at a deer, even at 10 feet. must be a mental thing.
i used to kill squirrels with an old bear compound with pin sight, out to 25 yards; no problem loosing a string on pests. it was a gift by someone here whose name i cannot recall. never deer hunted with it because of health issues at the time. bow ended up being stolen from a cabin on the river.
so, anyhow: i'm interested in an ultralight compound with 50-pound max, short axle length. now, i have a dozen XX75 500 feather fletched arrows for my 45# recurve that i'd prefer to use; i realize i'll probably have to cut them to length because the mechanical release will shorten my draw length (30" for a recurve).
i'll much appreciate y'all's advice. budget is, let's say, $500 ...

Shooting and killing deer with a 50 lb compound is very doable. Think fixed blade or cut on contact broadheads and heavy arrows 400 plus grains.
Side note releases do not have a effect on draw length your draw length is what it is d loop length and the release will effect anchor point.
My wife has talked about selling her hunting bow it's a 50 lb short ata bow and lightweight it won't under your budget of the draw length would work
As for your budget I think you could into a fairly nice rig for that or less depending on what get for accessories.

thanks, AR. definitely traditional broadheads, at least 125 grains ...

One thing I will add going up in arrow weight and adding weight to front end of the arrow effects spine by weakening it and you may have better luck with 400 spine which will add some overall weight but will also be needed for going to 125 gr heads and heavier inserts

I have an older High Country all carbon (riser and limbs) bow that is let go for 150. It weighs about 3 lbs.

Just for reference, what is “ultralight “ ?
I think most (bare) hunting compound bows will fall into the 3.5-6 lb range.
Carbon is obviously lighter than aluminum but will generally cost more.
Are you trying to just lighten your overall hunting load or just the bow?

sub 4 pounds. i like to keep my overall load as light as possible. i want a short bow because i almost always hunt from a chair. very occasionally will i hunt from a ladder stand.

Sub 4# on a rigged compound is going to be nearly impossible to achieve.

could i make sub 5 pounds? with simple single pin sight? 3-arrow quiver? no stabilizer?

Maybe with a carbon riser bow.

thanks. i'll look into it ...

A Bowtech Carbon Icon comes in at 3.2# bare, so it should be less than 5# even with a stab. As far as sights, just get a light weigh sight. The single pins gonna weigh pretty much the same as a 5 pin.
The Icon shoots really well and has draw setting, "comfort" setting pulls very easily. Solid limbs that haven't had any issues.