Kroil might be a winner

Plugged the chamber end of my Clark STC, put barrel cushioned vertically in a vise and filled barrel with Kroil in the hope of curing my FTEx and mixed plunk tests with 3 type of ammo. Aguila, Eley Club and old fuzzy wiped Eley Target Rifle. Let Kroil sit 18 hours, drained, used an oversized brush several passes. Followed by dry patches. 1st dry patch had some dark streaks, expected more.

At the range off a rest had NO FTExs.  About 40 rounds of each ammo at 25yds.
 
Had added a 1/2" riser extension to mount a Vortex Crossfire further back to were iron sights would be. Riser put shots 25 clicks straight high at 12 o'clock as compared to previous Dot position forward the chamber. Issue was getting oil splatter on the ocular lens from having to oil top round in mag to get pistol to function cleanly.

The groups were AMAZING! X after X after X. Club was tightest, followed by Aguila then Eley Target Rifle. Yes off a rest but the STC did not do this well before the FTEx issue.

I could put the sight back forward the chamber if the Kroil truely fixed the FTEx problem. But I think I like the riser extension and will keep in on for a few practices and matches just incase the FTEx returns.

Have the SW OEM barrel right now in the vise with Kroil. Tomorrow will drain, oversize brush it and dry patch and see what happens.

Thanks to the forum members suggestions and assistance in my working through the FTEx troubles.

See photo.

Great! I bet you had a lead booger somewhere at the forcing cone, just ahead of the chamber. Along with other crud.

I'd shoot it for as long as you can, before repeating such a treatment. For one thing, brushing can be hard on the barrel, especially if you go all the way to the muzzle crown. For another, with a regular pull-through patch regimen, it shouldn't be necessary. Watch for keyholing, or unexpected shots off-call, and see what the gun's telling you.

Long ago, I had a lead problem in a Model 52 barrel.  Suggestions from this forum were to buy a rubber stopper for one end of the barrel, to fill the barrel with Kroil, and leave it that way overnight.  This worked brilliantly.

I still have the Kroil, but don't use it unless I need to - too many warning labels about using it.  But it works!

As far as I know, my barrels are currently free of any "visible" lead.  They clean easily, and I use a patch, then a jag, until it comes out clean.

I recently had a different problem, with rounds not feeding cleanly into my High Standard guns.  The rounds were hitting the chamber, making a gouge in the top of a lead bullet.  With the round stuck in the chamber, I marked the right side of the round, then got it out of the gun.  That's how I knew what part of the bullet was hitting, and getting "dented".  Adjusting the feed lips on the High Standard fixed this, but I've been tempted ever since to soak the barrel in Kroil in case there was still some lead stuck near the chamber, perhaps in the "groove" leading into the chamber.  (Right now, the gun works great, so I don't want to mess with anything.)

I now realize Kroil is good stuff to have, for when it's needed.  So many people here had recommended it.  At the time, I had never heard of it......