Im going on a cow elk in the fall. The shot will be 100 yards or under. I have a savage 220 shooting 3" remington accutips. So my question is would it be ethical with the 20 ga? I have a 30-06 and a .270. But I am wanting to use the 20ga only if it would be an ethical clean kill.

yes I it will take an elk down, within 100 yards. I have the same shotgun, using the same ammo, topped off with a Leupold VX-II, I'm getting 3/4" groups at 100 yards, and 4" high dead center, this shotgun is a tack driver

You will be fine with the 20ga. and the accutips elk hunting. You are essentially hunting with a standard 45/70 load which is more than adequate medicine for elk.

You're firing a 45 caliber (I think) 260 grain slug at 1900 fps. Assuming you get the advertised 1900 fps you will have 2100 foot pounds of KE at the muzzle and at 100 yards you will still have 1500 foot pounds of KE.

Take the 30-06 for back up though. You're gonna be a long way from home and you don't want to be SOL on an elk hunt if you gun breaks.

Just as BigBulls and Bowhuntercop stated, you will be fine. What you have more or less is an updated inline 50 cal capable of repeating 3 shots before reloading!!!!
I think the projectile is either a 44 or 45 cal in a sabot and like BigBulls said, it should be pushing the 1900fps mark and that will get ya fresh elk tortillas for supper!!! And I agree again with taking your 270 or '06 as a back-up gun, JIC.

As everyone has said...it will do the job within the 100 yard mark. Just make sure it is legal to elk hunt with it in the state you are going to, not all states allow for shotguns for elk hunting. And as everyone else has also said...take the 270 or '06 as a backup...I never leave home for a hunt without a backup, which has saved my trip more than once.

Use a real gun....you have one...just use it!

A shotgun is a real gun, and under 50-75 yards i'd rather have a sluggun over a rifle anyday.

Why?

Good luck on yer hunt!

Maybe if you're a pheasant!

It's pretty clear to me that you've never hunted elk!!!!!

How do you know you can get a shot at 100 yards or less?

I have killed plenty of elk with shots less than 100 yards. But why would you want to limit yourself? If that cow is out there at 150 yards and that is as close as you can get, you could very well be under gunned with a 20 ga. At 200 yards you would under gunned for sure.

Again I ask, why would you want to limit yourself?

Take the 30.06 and the .270 as a backup. Take the 20 ga and use it to hunt the timber during late morning or early afternoon. The 20 ga would make a great brush or timber gun.