Classic Army M24 LTR Bolt Wobble

I recommend that you try punching them out and putting in new ones, but they should be a tight fit or else there won't be an improvement.
If you get that far, slather the end piece and the end of the inside of the cylinder with the strongest Loctite you can find, then assemble everything and peen over the ends of the pins with a hammer.
I did something very similar to a cylinder on a customer's rifle, and it worked very well after a few thousand rounds at high power he said.
Idk how long term is, but that's long term enough that I'd recommend it to you.

I recommend that you try using a punch and a hammer to drive the pins inwards until the end piece can be pushed out, then soak it in either paint stripper, xylene, petrol, or acetone in a bottle for a couple days, unless the end piece can be removed relatively easily.
Once it's removed, try putting a large metal bar in the cylinder and whacking it with a hammer while holding it, not resting on anything, and see if it comes out then.
If not, chuck it in an oven at pretty hot, or torch it/stove burner it until it just barely gets a light gold, then dunk it in water.
Repeat the bar and hammer thing and try again.

Then I guess you'll have to somehow remove the pins and put in new ones

Sadly that is the end piece of the cylinder, if you look closely you will see that the bins are being pulled through the end of the cylinnder due to probably peing poorly pinned.
I guess you would be best off soaking the cylinder in acetone or something for a while, and then just pour in really strong loctite to fill any gaps, going in from all gams and seams.

This will extend the life of the cylinder, but seeing that stretching on the end of the cylinder means it's days are numbered.
Idk if you can buy a cylinder either, but I can't find one specifically for the rifle so you may be out of luck.

Out of curiosity, what spring is in there and what is the chrono reading?

Did your friend ask you to fix the gun, or do you just want to use it, because if its the latter than a T11, APS/Barret Fieldcraft, or SSG10 would be much better options, and possibly cheaper than buying the parts, materials, and tools to fix the M24 depending.

As for the rifle's potential, I'd say its pretty dang close to zero since you can only buy hop chambers, barrels, buckigs, triggers, and pistons for the rifle, so it would be really sketchy unless you have a lathe and mill to make parts yourself.
Also, I'm amazed that a 500-400 FPS spring did that to the cylinder, as it must either be some cheese grade stuff or something else is going on.

Dang, well best of luck lol

I was thinking that it was similar to the cylinder head on a TM cylinder where you just whack the pin really hard and it allows you to remove the cylinder head.

Come to think of it, soak it in acetone and then TIG weld it, or preferably go somewhere that does welding.
Still, I'd only TIG or MIG weld it, anything else would be ridiculous.