It sounds as if the threaded 220 barrel is not fitting up into the 227 slide high enough.
Once upon a time, when fitting barrels on 1911s, you would use a barrel alignment gauge that had a firing pin diameter locating pin. You would fit the upper lugs, until the locating pin would fit into the firing pin hole in the slides breach face. I don't know if something like that could be used or not. Because of the tilting action of the barrel locking into the slide, .001" can be a lot!

Did you measure hood lengths? Are all the same? Try some "Prussian blue" to see where your interference is.

 

Barrel hoods are very close in length. I can 'push' the hood part of the barrel up into the slide just a hair so I don't think its too long. The pivot point seems to be where the end of the barrel goes thru the hole in the end of the slide but the barrel OD's are the same.

On all three barrels there are small dents on the bottom of the feed ramp where it hits the locking insert.

 

The muzzle is not the "pivot" point, it is the action of the barrels bottom lug, the locking insert, and the take-down lug. Just as with a 1911, you have the bottom lugs, barrel link, and slide stop pin that the barrel pivots on while the slide moves horizontally, the barrel pivots up when slide closes, and the barrels upper lugs mate with lug recesses in the slide.
The rear of the Sigs' barrel rises into the ejection port cutout, and acts as one big lug, securing the barrel in the slide. You need to check the original barrels fit into their respective slides, and that is your aim to fit the replacement barrel. Your downfall could be expecting it to be the same in both slides. For it to fit properly in "Both" slides, it may be looser in one of them. Sigs tolerances are close, but if one slide is cut at minimum tolerance, and the other is cut at the maximum, you can see the problem. Plus you are talking 2 different models. I don't think you can expect perfection!

 

THX for the reply. By pivot I meant with the barrel in the slide the chamber end of the barrel can't go higher in the slide (unless I push it hard) because of the tight fit of the muzzle end of the barrel in the end of the slide. I can push the chamber end into the ejector port ~0.5 mm.

The threaded barrel in the P220 slide fits and works fine on the P227.

Your tolerances remarks make sense.

 

I think you are correct that the "pivot point" of the barrel is the bearing surface in the slide at the muzzle end.

It sounds like the barrel isn't fitting UP high enough in the slide for the feed ramp to clear the locking insert. If the length of the barrel hood fits in the slide ejection port opening, then the top of the barrel (just forward of the barrel hood) will need to be ground to allow the barrel to sit higher in the slide.

I see where one of the barrels in your pic has been ground this way. Am I correct that the center barrel is the original P220 barrel and the left one is the new threaded barrel? Have marked your pic to show the area in question:

 

Thanks ThnkFrst.
" If the length of the barrel hood fits in the slide ejection port opening" It does.

" then the top of the barrel (just forward of the barrel hood) will need to be ground to allow the barrel to sit higher in the slide." The top of the barrel does not touch the slide (unless I press the barrel up) so grinding more off would not help.

LEFT = Original P227 barrel
MIDDLE= Original P220 barrel
RIGHT = P220 threaded barrel

I'm wondering why all three have dings on the feed ramp where it hits the locking insert. Not sure if the P220 barrel had them before I put it in the P227. Maybe on the P227 slide the 'bearing surface' at the muzzle end is a really tight fit or just at a slight angle. Really tight fit is normally a good thing.

 

I does sound like the bearing surface in your 227 slide is tight, or tighter than your 220 slide.

I've only had one occasion to rework the slide bearing surface and that was to remove the finish after having it ceracoated. I don't have a course of action to recommend to you.

 

Barrel OD
227 - 0.588
220 - 0.588
Thrd - 0.589

Hood
227 - 1.3470
220 - 1.3485
Thrd - 1.3495

Thickness top of chamber to bottom of ramp
227 - 0.8320
220 - 0.8330
Thrd - 0.8295

Thickness top of chamber to bottom of lug
227 - 1.0965
220 - 1.0970
Thrd - 1.0980

Slide bearing surface
hard to measure accurately due to angle of hole top to bottom
Side to side is both 0.599

 

Hard to measure I think its close
With the barrels in the slide
Distance from the top of the slide to the top of the chamber.
227 - 0.065
220 - 0.065
Thrd - 0.078
Thrd - 0.066 (if I press the chamber up into the slide with my fingers)(I may be wrong but this tells me the hood does not need to be ground)

 

You're right, the hole in the front of the slide is hard to measure. It's actually two holes machined on different horizontal axis.

If you insert the muzzle of the barrel in the slide (from the front of the slide) just enough to clear the bearing surface and push down on the breach end, do you see a difference in the angle of the barrel relative to the slide between your 220 and 227 slides?

I see the threaded barrel OD is 0.001" larger than the other two. That not a lot but it's not helping. How far back from the muzzle are you taking those measurements?

 

About where the main smiley is.

 

Sig said I can send it in free of charge and they will try to figure it out. The plan is to send it back with one of my MCX BCG's that must get swapped under the recall.

 

Sounds like a good plan.

 

Got my P227 back yesterday. No parts were replaced. Note said they fit the barrel to the gun. The only shinny metal I saw was where the barrel goes thru the end of the slide so I think they opened up the angle of the hole a little. Turn around time was ~1.5 weeks. Thanks Sig!