Is there such a concept as breaking in a new gun? In other words, should I shoot a brand-new gun several times before I trust sighting it in?

I have always heard shoot it and clean it for about 10 rounds or so. Had pretty good luck.

What's the purpose of the gun?

A defensive pistol I would say several hundred before I'm totally comfortable.

Just trying to decipher if this new gun just isn't very good with the specific load I'm shooting, or wondering if I shot it maybe 20 times if it would suddenly get in a groove.

New Savage 220 with Remington AccuTips. Supposedly these two were made for each other, and other people brag about how well it does. This gun is all over the place, and so was my last gun with that same load. I am terribly unimpressed with these shells.

If those aren't working for you, try other loads and see how they do. In an article I read a couple of years ago, they also recommended Federal Trophy Bonded slugs. I've also shot some Brenneke's through mine with acceptable results. Mine just grouped the best with the 2 3/4" Remington AccuTips. Would not group good with the 3" AccuTips. Weird.

All of your scope screws tight?
Tried varying torque up and down a bit on the action screws?

Tried a different lot # of the same load? There are variables from lot to lot.

friend of mine was told recently on a cw9 400-500 rounds! hell with that

Mine was like that in the beginning. For whatever reason I couldn't shoot it using a lead sled. Went to bags and the problem went away. May be a mental thing but there was a big improvement. Every 220 I've ever seen will group with 2 3/4 accutips. The 3" accutips not so much. Which ones are you trying?

Let me say it this way.... I could have unrealistic expectations from a slug gun too. My previous gun was an H&R with the heavy bull barrel, it would SCOUT'S HONOR shoot 3" Winchester Partition Golds in a 1" circle at 100yards, as many shots as you wanted to shoot. (All from a Caldwell Lead Sled)
But that same gun struggled to shoot the AccuTips in a 4"/5" circle. Now some folks would say that's "good" for a slug gun, so maybe I'm just expecting too much. I absolutely expect to shoot 2" groups OR LESS at 100yds, period. Understand that I frequently shoot at deer from 150+ with this slug gun, so it MUST be more precision than "hand size groups" at 100 yards.

I dunno, maybe I'll take it again with a couple of other brands and see what it does.

I'm shooting the 3". I do have two boxes of 2-3/4's in the cabinet, so I'll try those too. I just really wanna shoot a super hot load, because I frequently take shots of 150yds or more.

If it doesn't work out for you I'll give you $20 for the gun.

You know what, make it $50.

My 220 will do what you said your old gun would do. But only with the 2 3/4 a accutip slugs. It has no problems out to 200 yards shooting or killing.

That was gonna be my suggestion too...I have never been able to get 3" accutips to shoot well out of anything.

Funny enough, been doing a bunch of Google research, and it appears that these guns REALLY like the Federals. I have never shot a Federal slug, but I think I might pick up a box for giggles.

In my limited experience with slug guns, velocity make all the difference in the world. Some barrels like fast slugs and some don't. My BinLs Mossberg shoots 3" Lightfields all day long in a 2" circle, but not the 2 3/4.

My dad has a Rem 1187 slug barrel that like SLOW slugs. Slower the better.

My BinL dads slug gun will only shoot Hornady SST slugs.

Thing about slugs is they are so expensive, it sucks to have to experiment.

Try diffrent ammo.Far as self defense break in least half a case 500 rounds.

There are probably as many opinions on this subject as there are calibers to pick from. A lot of folks believe a break-in period is in order. Google "fire lapping a barrel".

Fire lapping works. I had a brand new 270 single shot Handi rifle that was a scattergun. About 6 inch groups at 100. Fire lapped it and tightened it up to 2 1/2 inch groups. Turned that rifle from a tomato stake to a decent rifle.

i figured after 50 - 60 deer they were broke in . i get a new gun i sight it in and hunt . the next year i check it (few others i might hunt with) and hunt . if my first two shots hit where i sent them , i put the gun up .

My slug gun shot the hornady sst's really well. Wouldn't shoot the Remington for crap