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cohland

Importance of Barrel Crown

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Recently I finished upgrading a Springfield 1911 Range Officer 9mm pistol, to be used for USPSA Single-Stack Division competition. Since previous models of this pistol that I have owned have had excellent accuracy out of the box, I was somewhat surprised to have accuracy problems with this one. Try as I might, I could not get a decent group at 15 yards, which is the distance at which I set sights for USPSA guns.

Now, my definition of "good group" is probably sufficiently different from most that I need to explain myself. To test a pistol, I shoot it from a table using a modified pistol rest that mitigates the effect of my ability to jerk the trigger. I use my regular (corrected) shooting glasses, and my eyesight isn't the best (I have trouble with sight alignment), so what I can get out of a gun is usually less than it can deliver to a better shooter with better eyes. While I didn't measure the group, I'd say it was about 4" across. Not good.

My previous attempt at the same type of pistol gave me about a 2" group immediately. Clearly, if I was planning to use this pistol in competition, some improvement was in order.

What was different? I recall that the previous Range Officer I set up had a particularly sharp and uniform pattern of firing residue at the muzzle, like a little star pattern. Until now I had never connected that with accuracy, but with the new Range Officer I noticed a difference: it produced a somewhat raggedy residue pattern. Examining the muzzle crown closely with a 30x loupe, I could easily see that the ends of some of the lands in the barrel were uneven at the crown, as if they had been cut at a very slight angle. So, I figured I needed a muzzle crown job.

A call to a local gunsmith got me an estimate of $125 and three weeks' wait. Pondering this for just a bit, I thought I'd go look on the web to see what I could find. What I found was Bill Springfield, whose website offers barrel crowning:Bill Springfield - www.TriggerWork.net, among other services. After a quick exchange of email messages (the man answers email, people!), I shipped my barrel off to Bill, expecting to see it a week later. Four days later it arrived, with a new 11° target crown.

The following day I took it to the range, and shot a couple of 2" groups at fifteen yards, well before my morning coffee had kicked in. Delighted, I took a photo of the residue pattern, so that I could show it off, and here it is:

Crown_zpsjhq4ygdy.jpg

Yes, that's oil all over the front of the gun. When I'm breaking in a 1911 I run them pretty wet, with lots of oil on the barrel and bushing.

If you are having accuracy problems with a pistol, look at the powder residue pattern on the muzzle after you finish firing 50 or 100 rounds, enough to leave a pattern. If it's not uniform, you might think of having the muzzle re-crowned.

Chris

Edited by cohland

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Great write up and 100% true. The star formed on the muzzle of a gun can tell you a lot about what's happening to the bullet as it leaves. It will also tell on bullets with whacky bases too.

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Target crown is very important for accuracy. I notice that your barrel bushing isn't a very tight fit, I would be willing to bet that is you replaced the bushing with a tighter fitting one that your groups would be much tighter than they are now.

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That is a shadow on the bushing, caused by the barrel.

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Target crown is very important for accuracy. I notice that your barrel bushing isn't a very tight fit, I would be willing to bet that is you replaced the bushing with a tighter fitting one that your groups would be much tighter than they are now.

I think that's just a shadow you're seeing.

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Target crown is very important for accuracy. I notice that your barrel bushing isn't a very tight fit, I would be willing to bet that is you replaced the bushing with a tighter fitting one that your groups would be much tighter than they are now.

I think that's just a shadow you're seeing.

Correct. The bushing-to-slide and bushing-to-barrel fit are both excellent, straight from the Springfield factory.

Chris

Edited by cohland

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Target crown and a barrel bushing that requires a tool to remove are both very important and not very expensive.

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PS: Bill Springfield charged $35 for the muzzle crown work, including return postage.

Chris

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