Re: The Over-Rated Crown
I have seen, as others have, varing results with recrowning. I makes me wonder whether calibre, velocity, bullet jackets, BC, and other factors have an effect on the results.
My story is a little different, maybe to the other end of the scale.
I was given a .204 some months back, it was new, from a reputable manufacturer, out of the box, and did not shoot a 10 inch group!
Long story short, my friend, the dealer asked me to take the rifle and see if could be fixed, I carried out a few basic tests to see if there was a simple solution.
Upon visual inspection, all i could see was a small indent on the crown. I was sceptical that this was the trouble. Hey 10 inches at 100yds!!
I took a tight patch and felt the bore for any variations, none where found.
The rifle had fired an unknown number of shots, during the run in, by the owner, and it was returned to the importer for a warrantee claim, so i gave it the sweets and JB paste to be certain the bore was clean. it came up pretty good.
I took the bore scope and had a good look inside, nothing was out of place for a factory rifle.
I went to the range and fired 5 shots, I was also given the test target, the customers target was a good reference as the new target was similar, 10 inches! wow!
now on further inspection i concluded that the group had in fact blown out, in favour of the damage to the crown ie indexed at 10 o'clock if you like in line with the damage.
Not certain what to do next, and knowing my friend had just bought a cheap action, i proceeded to see if i could change the 10 inches down some what, to something less than an inch, on the target.
Those of you who shoot 204's will know they are very capable, with less than half inch groups being obtainable out of the box.
Not having the correct tools to recrown the barrel and not really troubled by the result i took the burr off the damaged part of the crown with a screw driver to see if the resultant target showed any improvement. To my surprise the consequent group was around 8 inches, not good but different.
I knew if i was successful that a competant smith could take 1/8 of an inch off and reshape the crown so i was underterred. i took a drill and removed some more material trying to get below the damage part or the bore.
I did this in stages as to see if i was getting any where. Another 5 shot group showed an improvement down to 6 inches, than 4 inches. At 4 inches some where landing in the bull, while others scattered out in a radius, I had achieved my goal. I stopped there as to not cause further damage to the barrel and it was time to let a machinist complete the work in a professional maner.
The barrel was soon recrowned and now shoots as it should. I know we are not comparing apples here, but i was very taken by your findings.
At any stage you are able to conduct more tests, it would be great to add some other calibres? To see whats really in a crown!