Hopefully my sharing of this might prevent someone else from making the same expensive mistake that I did.
I originally saw the two big craters in the barrel........thought "OH S##T", and got onto Phil Jones, my gunsmith. Phil reported the issue to Broughton straight away and asked me to get the barrel back to him asap.
Phil rang when he got the barrel in the mail, and as a good mate would, asked me to explain to him how I had managed to pound the hell out of the ramp up into the "Leade" with my cleaning rod.
When I went out and saw him a few days later, this is what he had been looking at through his trained eye, with his borescope......

Uploaded with ImageShack.us (You can see where the whole lower circle has been pounded)
So of course i told him not to be *F%$#ing ridiculous.........i use a proper bore guide every time, take extreme care and my Proshot rods, jags and brushes are in perfect condition".
So then we started working through it, and by now the pennies were dropping pretty fast............i was working it all out pretty quick.
Here is a photo of a top quality Redding "accessory" that can help you ruin a $900-00 barrel replacement job too

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This is Redding Application Media, tiny ceramic balls to which you add graphite to, and its a perfect neck lube for reloading.

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It is also a perfect way to put these tiny, perfectly round, little ceramic "cannon balls" into a case, if it holds the tiniest hint of lube , left over from neck turning.
Fire a shot from a case with a couple of balls inside it, and one or two might smash the ramp into the leade, and then might pull up half way down the barrel, half welded into a land or a groove. A few more shots, a bit more heat, and you can imagine what might be happening. A ceramic ball half stuck to the barrel gets another 105 gr VLD over the top of it, then another , then another.
Eventually with the right amount of heat, and pressure as a 105grainer at 3100 fps smashes over the top again, and you get this

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Or you get this

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In just a few shots , you can turn a superbly accurate, hummer of a barrel that just cost over $900-00 to have fitted, into a tomato stake.
The prevention is pretty damned easy.......clean the cases out properly with Shellite or similar after neck turning, blow out with an air compressor and dry properly. No more problem !!
My mistake had been to use cotton buds and patched wrapped around a 22 cal nylon brush. I genuinely thought that I was doing a really good job, but I simply didnt clean the cases well enough, as I clearly didnt get rid of all of the lube.
I want to acknowledge the appropriate response from Tim North at Broughton when they were first advised by my Gunsmith that I had "a problem" with a new barrel. They told Phil immediately that if he thought the problem was "their barrel", they were happy to replace it, or credit it on the spot, with no questions asked. You just couldnt ask for a fairer response from a barrel maker than that.
As it turns out, none of it had anything to do with Broughton. It was 100% my own fault
The barrel has now been replaced with another Broughton, and thankfully it seems to be just as accurate, and just as easy to break in, as the first one that I wrecked.
My old grandfather used to say that "bought experience was the best type to have, as long as you kept the receipts" !!