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44Magnum
February 24, 2009, 01:27 AM
Say you have a pistol with a crown that looks a little messy upon close inspection. The gun, however, is extremely accurate. Do you have it fixed or not? :confused:

JohnKSa
February 24, 2009, 02:06 AM
If the gun is extremely accurate then don't mess with it.

44Magnum
February 24, 2009, 10:28 AM
That's what I was thinking. Wouldn't it be a kick in the teeth if the accuracy got worse after a repair? :rolleyes:

I hate to say this, but it really makes me wonder just how important a "perfect" crown is on a handgun.

JohnKSa
February 25, 2009, 03:36 AM
Not that important. Here's a test done with rifles. It made a difference, but not that much. Not enough that most pistol shooters would be able to see a change.

In other words, there are other factors in pistol accuracy that will tend to swamp out issues with the crown. If you're shooting around a half-MOA at 50 yards then a damaged crown will show up in your groups. Otherwise it's not likely that it will affect you much.

March 2008 American Hunter

“bullshooters” column

Will Damage to a Rifle’s Crown Hamper Accuracy?

Four barrels were tested before and after intentionally damaging the crowns.

Tested @ 50 yards at an indoor range.

Cleaning rod damage (cleaning from the muzzle with an aluminum rod 100 strokes--slight visible damage) Group went from 0.550” to 0.874” and shifted 0.006 down & 1.059” right.

Gravel damage (dragged muzzle down in gravel and then mashed into the gravel with high force—mild damage) Group went from 0.326” to 0.790” and shifted 0.061” down & 0.151” left.

Cut off with a hacksaw and not recrowned damage (severe damage) Group went from 0.329” to 0.945” and shifted 1.101” down & 0.457” right.

Crown intentionally damaged with a file (severe damage) Group went from 0.506” to 0.848” and shifted 0.020” down & 0.248” right.

Muzzle drilled out to about .45 cal with a drill bit. (severe damage) Group went from 0.506” to 0.697” and shifted 2.206” up & 1.032” right.

44Magnum
February 25, 2009, 01:24 PM
Oh yeah. I suck way too much to notice anything like a few hundredths of an inch. :D

Thank you for the information.

Harry Bonar
February 27, 2009, 12:03 PM
Sir;
Yes it's important! Get it recrowned on a good lathe by a professional! And, it's not a matter of "hundreds of an inch" it's a matter of ten-thousandths of an inch. Muzzle crown is crucial - I'd get it fixed.
Harry B.

44Magnum
February 27, 2009, 01:03 PM
There is only a little bit of barrel sticking past the slide. How much "excess" barrel would a recrowning job take?

musher
February 27, 2009, 01:38 PM
Well, I'm a big subscriber to the "if it ain't broke" approach. No way would I mess with the muzzle of a firearm I would describe as "extremely accurate"

Just think about it in terms of risk:reward. How much more accurate do you believe the firearm could be? That's your potential reward. How much less accurate do you think it could end up. That's your risk.

JohnKSa, I haven't read that column, so I don't know what the methodology or sample sizes were, and have no way of telling whether the numbers are meaningful or not, the examples in your quote show increases in dispersion on the order of 60-70% of the premutilation figures. Pretty big difference.

Oh, and cleaning up the crown should only take off what's needed to remove the visible damage. How much you lose is directly related to how deep the nicks are. Given your description, I'd guess a few thou is all you'd need to clean it up. Not enough to visibly shorten the barrel.

44Magnum
February 27, 2009, 02:24 PM
Yeah, I honestly don't know how it is possibly as accurate as it is. When you shake the gun you can hear the slide wiggling against the frame and the crown looks like a guy cut it on a lathe with a dull nail. But the groups are impressive. :confused:

JohnKSa
February 27, 2009, 04:17 PM
How much "excess" barrel would a recrowning job take?It depends on how deep the imperfections in the crown are, but I would be tremendously surprised if it changed the length of the barrel to any significant extent even if everything is recut.

But unless it's pretty badly banged up, you don't even need to have it recut, you can just touch it up yourself if you're so inclined.

http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=855&st=&s=