I'm pulling a factory 24” stainless 700 5R .308 barrel that wasn’t quite shot out for something much heavier. I actually wanted to try an abrasive after recently watching
@Frank Green on Cortina’s podcast, then I saw this thread & thought “what the hell, why not.” So I bought some Iosso Bore Cleaner & went to town.
I wrapped an Outter's sythetic patch the full length of a .30cal nylon brush, so that the brush could not contact the bore directly. I soaked the patch in Slip 2000 Carbon Killer, applied a reasonable amount of Iosso Bore Cleaner, then ran it through the barrel 20 times. I did not allow the patch/brush to exit the barrel, I did not use a bore guide, & I did not let the solvents sit in the barrel for longer than 15 minutes.
1) I expected there to be more damage throughout the barrel & did not expect so much damage to be concentrated in the throat. There is much less damage after 2” & it is mostly lighter scoring on/to the lands. Not using a bore guide could have exacerbated the throat damage, but I don’t think that’s enough to fully explain it. I wonder if the steel nearer to the chamber has become slightly more brittle or fragile over 1,500 rounds of use & was more easily scored?
2) I didn’t expect the corrosion to be so defined or concentrated. It's possible the 2 cleaning agents reacted with one another, worsening the effects. I definitely didn’t expect the location @ 5” from the breech.
3) Prior to this, the only solvents used on this barrel are Hoppe’s No. 9, Shooter’s Choice MC #7 & Shooter’s Choice Copper Remover.
4) This is the first time I’ve ever used an abrasive cleaner. Unless I’m doing a similar test or demonstration for a friend, this is the last barrel I’ll ever use an abrasive cleaner on.
Clip of the throat damage
Clip of some new corrosion 5" from breech
Unfortunately, the pre-Iosso photo is the best one I have, which was taken 3 months ago without cleaning & ~500 rounds prior to the Iosso. If I have time, I might shoot some groups before the barrel swap & then use Iosso again with an unprotected copper brush to see how much worse I can make it. What’s the over/under on 1.5 MOA groups?
. For sure, the worse looking barrels I have, a 42 year old 7 mag Ruger and a 1898 30-40 Krag, both shoot well within what I need them to. You wouldn’t know it by looking down the barrels with a Teslong though.
