"...What are the chances that the barrel is damaged?..." Can't imagine any way the tube could take a hit and the barrel not being severely damaged. I'm suspecting that hole isn't the result of a bullet strike. Even with a cast bullet there'd be far more damage.
Parts are fairly easy to come by though. Mag tubes run $22.05 at Gunparts.
With a small caliber, low velocity, lead bullet, that's actually more damage than I would expect. I think it was 'standard velocity' .22 LR at close range.
I've been party to, or the
donating party for multiple firearms and firearm parts that were used as targets.
You'd be surprised what most firearms can take before they show real damage.
Grips, stocks, and plastic parts go quickly. But frames, barrels, and substantial steel parts can take much more abuse than you might imagine.
For example:
I have a Yugo 24/47 Mauser barrel sitting about 4 feet from me right now. I removed it from a rifle that was used as a target ...and I plan to use the barrel in the future. It took
dozens of hits, at 50-75 yards, from everything ranging from .22 LR to 7.7x58mm Jap, from .243 Win to .30-06, from 7.62x54R to .45 Auto, from 9mm to .44 Mag, and everything in between.
.22 LR and 9mm didn't even hurt the adjustable rear sight, let alone other parts of the barrel. They just left lead and copper smears. And the big boys? Direct hits with jacketed bullets resulted in no detectable damage, anywhere. Even when the chamber area was hit by EIGHT consecutive rounds of 7.7x58mm and at least 6 rounds of .30-06, the only evidence was a few jacket fragments nearby and the collection of lead and copper smears.
The receiver itself took 13 rounds of 7.7x58mm to the same 3-4" area before it cracked on the left side. And then it took about 30 more rounds of 'high powered' rifle and 'magnum' handgun rounds to break a piece off.
And then there's this guy...
It looks pretty bad.
...But that represents about 300 rounds that did almost nothing more than shatter the grips - everything from .22 LR to .44 Mag.
Most of the damage was actually done with .45 Auto running really hot 230 gr FMJ loads at close range (~10 feet). .22 LR, .380 Auto, and .38/.357 with lead bullets really didn't do more than leave lead smears. 9mm and .44 Mag at 35 yards caused some deformation, but the pistol still functioned and I would have felt safe firing it (well... if it wasn't already being used as a target due to being ridiculously unsafe).