Okay, I grabbed my mid-production ('98) 3913, my late production 3913TSW, and 3 older 3913/6906 barrels for some quick comparison pics.
The 3913 has seen a fair amount of use, meaning at least several cases of various duty loads over time, which have included standard pressure 147gr, 127gr +P+ & 124gr +P. The 3913TSW is still pretty much pristine, since it was only used as a reserve duty weapon for several months and I was the only issued user to ever shoot it. A handful of range sessions. Less than a thousand rounds? It's seen some retirement qual shooting, but not a lot (not like I used to shoot all the time
).
The 3 spare barrels are used, from early production 3rd gen guns.
So, the 3913TSW frame, being lightly used, has this amount of wear marks from the barrel dropping down onto it, during live-fire cycling (Pretty similar on both sides):
(The dark grey lengthwise "lines" on the top of the frame rails are due to the way the lube on the wear spots reflected the 3 lights above the gun while taking the pic. When I wiped off the lube it looked different, but I'd already taken the pic and didn't feel like taking another one of it.)
The left and right sides of the bottom of the rear of the barrel, showing the rear edges of the chamber area and the camming lugs. I apologize for one of them being a bit fuzzy on the cam lug point, but it shows the rear/bottom edge of the barrel chamber.
Notice how clean and smooth the edges and points are on the this late production gun. I haven't felt the need to do any deburring (yet
). Sure, there are some various machining marks/lines visible, but they don't "stick out" from the surface like burrs.
Now, my older 3913.
Note how the wear mark for the barrel is noticeable on the left side of the frame, but barely a "scuff" on the right side. When you look at the pics of the bottom of the barrel, you might notice the R/side rear corner is very smooth and rounded off. I also deburred the rear corners and edges of the barrel camming lugs many years ago.
Now, the older spare 3.5" barrels. A mixed bag. You'll see how the edges can vary.
And on this one, you'll note that the R/side barrel camming lug has a nasty and uneven trailing edge and point. I can imagine that uneven and sharp edge probably left some noticeable wear on the frame cam lugs of the aluminum frame of the gun from which it originally came. Ugh.
BTW, if anyone wonders about the way the rearmost edges of the barrel and feedramp sides of the older 3913 (and 6906) barrels show a sort of discoloration, that's because in those days the factory dipped the rear of the barrel chambers (tabs, mouths and feedramps) into a solution for an electrochemical polishing final step. It's visible as shiny/dark spots on the back edges and corners of the old barrels in my pics, and really noticeable in this pic of my 3913 barrel, visible running up/down the side of the feedramp, and under the bottom.
My 313TSW barrel doesn't show it because they changed and improved their overall production and finishing steps in the later production guns. Notice how the rear corners of the barrel chamber floor and the cam lugs are clean, smooth and evenly shaped? More consistent than the older barrel manufacturing, but considering the money they were spending on upgrading their equipment at the time ... it ought to be.
Too bad that just about the time they'd reached the pinnacle of 3rd gen design and manufacturing, they decided to discontinue them in favor of plastic. Dammit.
I've seen some new barrels where the rear edges and corners were a bit sharp, or even burred, but they came that way.
