325 delivered per 1k at sgammo   https://www.sgammo.com/product/wolf-ammo-sale/1000-rounds-308-win-145-grain-fmj-ammo-wolf-steel-case-non-corrosive-ammo-mfg

Anything that would have blown apart a perfectly good barrel, would have definitely caused other issues. Squibs don't cause damage because 1 bullet hits another, they cause damage due to over-pressure which happens the entire length of action. Blown case, blown extractor, stuck case , up to and including broken action and receiver parts. As far as accuracy being affected, well that can easily be tested; but I wouldn't jump to say that should have been immediately noticed.  If the shooter was just plinking offhand at 25 yards, then it would likely produce enough accuracy to not be obvious.    

Join us every Friday for our 40-yard sharp shooting competition. 40-Yard Friday’s Details: – Hit a playing card from 40 yards to qualify for the semi-finals at the end of March.
– Iron sights, 8 shots, 9mm and above.
– One Final sharp-shooter will win a Premium Membership valued at $495 and have Bragging Rights! Semi-finals will be held at the end of March. Stop by the TTC range and take your shot!  

I have a LOT of guns for sale. Have not put all the details together yet, nor pricing. PLENTY of S&W wheel guns, one Ruger Single Action, several bottom feeders as well. Lot's of long guns also. All will be listed on Gun Broker soon when I finish the details.

Yes sir it is indeed a model 18-3  K-22 Combat Masterpiece they made 2 Combat Masterpieces a K-22 later know as the Model 18 Combat Masterpiece and the K-38 later known as the Model 15 Combat Masterpiece .The K-22 is the exact profile as the K-38 in weight grips and sights and was developed as a training pistol for the K-38 but in caliber .22 and as such maintained the nomenclature "Combat Masterpiece" They also made K Models like the 16 and 17 and called them the K-32 and K-22 Masterpiece sans the "Combat".