I ask because I am looking closely at the new sp101 snub I bought and it has a slight hair gap between the barrel and the frame when viewed from the outside. Looking at the top half of the barrel here. Just want to make sure everything looks good to go. It looks like this on both sides on the top half of barrel.

Only other question I have is that my gun rattles/clangs when I shake it, which I understand to be the sound of the transfer bar. Do all 101's/gp's do this? I don't remember my last one doing this.

I'm not sure about the barrel, but I just checked my GP100 and it does not rattle, I seem to remember my SP101 had a small rattle while my LCR definitely rattled.

Yes, the barrels are screwed in.  The rattle is almost certainly the transfer bar.  Fairly common on Rugers.

So, would a small gap between the outside of the barrel lug and the frame be something to be concerned about?

Nope.  That is normal with most single piece revolver barrels.  It should be real close but a small gap (thickness of a piece of paper or three) is acceptable.

I'd say mine is piece of paper thick. Thanks

On another note, I shot it today and it wouldn't eject the brass after finishing a cylinder. We worked through 5 different kinds of ammo and only one was able to be ejected easily using the rod. The rest had to be pulled out by hand. Shipping it to ruger tomorrow

I'm sure they'll get it fixed up.

Ruger will make it right.

What loads were you shooting? When I shot 357mag, they were a little tight on ejection but when shooting 38spl, the brass practically fell out, this is due to the brass swelling of course.

Did  you clean the cylinder real good?  If you or someone prior to you shot a lot of 38 special (especial lead bullets) in it and then you tried to shoot 357 mags you might have a problem with cases hanging up on the fouling and residue in the chambers from the shorter cases exposing more of the chamber.  Before you send it give it a good look in the chambers.

It was a brand new gun, so carbon buildup wouldn't be a problem. I did shoot one cylinder or 38's to test the ejection and they ejected just fine. Seems the cheaper ammo was tightest. American eagle, blazer brass, etc. The only 357 to not cause an issue was hornady hollowpoints. I also had cleaned the gun prior to shooting and had the gunsmith at the range take a look to no avail. I had an sp101 once before and the cases got a little tight sometimes but they could always be ejected with the rod. These were so stuck I feared breaking the rod.

If the gap is on the bottom of the barrel between the shroud and the frame, that's a necessary clearance to prevent the barrel from scarring the frame when the barrel is screwed in.

Ruger pistols, especially the SP-101 often rattle and it's either the transfer bar, OR the ejector rod.
In the number of them that I worked on and the three I owned, the major rattle was the ejector rod.

In some revolvers it doesn't take much .38 Special to cause .357 cases to stick.
Order a couple of BRONZE chamber brushes from Brownell's to clean the chambers.
The chamber brushes have much stiffer bristles then over-sized bore brushes and do a far faster, better job of removing fouling from the chambers.

Got the gun back from Ruger. They swapped the cylinder and ejector. Haven't shot it yet, but I dry fired and noticed the lockup/timing is slightly off on two of the cylinders. It's probably functional but feels like it was done a little sloppy. When slowly dry firing, two of the cylinders won't go into full lockup when they're supposed to before the hammer falls. They end up in lockup after the hammer falls but right before the hammer falls you can rotate the cylinder manually a few degrees and audibly/visually see it click into place. I'm not impressed. They had me send it back again. After shooting the gun only 30 rounds and having to send it back to ruger twice I am annoyed. It has been at the factory SIGNIFICANTLY longer than I have had it in my possession. I am heavily inclined to part with this gun and buy an airweight 38 for about 100 dollars less.

I thought I was the only person in the world who had gotten a crummy SP101!
Fortunately they fixed mine the 1st time around (lockwork broke near the bolt stop on mine, locking up the trigger.)

Good luck with your 2nd repair. At some point you may want to escalate it to someone higher up at Ruger.