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  #1  
Old 10-03-2004, 06:25 AM
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Barrel Crown


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I've a question that's been nagging at me. A good number of new guns are coming from the manufacturer with a recessed crown. As I understand it, the recessed aspect is to protect the crown from damage, which will affect accuracy, and ensures that the crown is true to the barrel. Just how is it that a damaged crown affects accuracy? Not significant damage that's obvious to anyone, but minor damage that isn't obvious to the eye.

This doesn't seem to make sense. I could see it if there was significant damage to the end of the barrel whereby gasses were allowed to cause a bullet to somehow veer from an equal barrel length. Even a very small amount of unequal pressure on the base of the bullet should be sufficient to affect accuracy, but how much damage, such that it affects hunting accuracy out to 400 yards. Is all this barrel recrowning just some more sizzle to sell the latest offerings?

I can't envision such a level of damage from events such as cleaning a rifle, whereby an aluminum cleaning rod is going to damage the crown, yet I see reference to that fear in many places. Maybe I'm just careful, or lucky, but I've always cleaned from the muzzle end, and have never had any affect on accuracy, much less any visible damage.

Also, barring a manufacturer's defect, I find it very hard to believe that a reputable barrel maker's product doesn't have an adequate crown for hunting accuracy out to at least 400 yards.
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  #2  
Old 10-03-2004, 06:55 AM
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Quote:
Originally Posted by Lion
I've a question that's been nagging at me. A good number of new guns are coming from the manufacturer with a recessed crown. As I understand it, the recessed aspect is to protect the crown from damage, which will affect accuracy, and ensures that the crown is true to the barrel. Just how is it that a damaged crown affects accuracy? Not significant damage that's obvious to anyone, but minor damage that isn't obvious to the eye.

This doesn't seem to make sense. I could see it if there was significant damage to the end of the barrel whereby gasses were allowed to cause a bullet to somehow veer from an equal barrel length. Even a very small amount of unequal pressure on the base of the bullet should be sufficient to affect accuracy, but how much damage, such that it affects hunting accuracy out to 400 yards. Is all this barrel recrowning just some more sizzle to sell the latest offerings?

I can't envision such a level of damage from events such as cleaning a rifle, whereby an aluminum cleaning rod is going to damage the crown, yet I see reference to that fear in many places. Maybe I'm just careful, or lucky, but I've always cleaned from the muzzle end, and have never had any affect on accuracy, much less any visible damage.

Also, barring a manufacturer's defect, I find it very hard to believe that a reputable barrel maker's product doesn't have an adequate crown for hunting accuracy out to at least 400 yards.
Don't believe there is any real difference between types of barrel crowns, but the recessed crown is proably the easiest to get right. Not sure it's the best protection.

Do believe even small burrs, dings, or buggers can have adrastic effect. This one is easy to test if you are able to recrown after you've buggered it up. IF you've one that (1) you wouldn't mide having a 1" shorter barrel (2) you've got the ability to recrown, then can have a go at knowingly damasging the crwon and testing the effects of the damage. IF you don't do anything too drastic, can get four or five tests done by removing 1/4" of barrel, recrowning, and damaging it in a differnet way.

Have thought that the reason barrel crowns seem to have such a large effect on some rifles is that that little nudge provided by a bad crown happens just when the bullet is at it's least stable point. Pretty well documented that in some calibers (usually were you push the edge of barrel twist/bullet length) the bullet is a bit unstable at exit; a little nudge here would have a large effect.

A dead clean aluminum rod doesn cause the damage that a dirty/gritty rod does. Aluminum isn't the best choice for a cleaning rod...is soft enough to pick up and hold grit transforming an uncleaned rod into a pretty good lapping stick.
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  #3  
Old 10-03-2004, 09:32 AM
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Check out the rifling near the muzzle on old military rifles - particularly ones like the M1 Garand which must be cleaned from the muzzle (and often old Winchester lever guns as well), and quite often there isn't much rifling left.

Cleaning rods can and do cause barrel damage, although it takes time. Keeping the grit wiped off of the cleaning rod, and using a bore guide, will help slow that process down.

I've cleaned a Marlin 39A from the muzzle, with a jointed brass cleaning rod, back when I didn't know any better. Can't see any damage, but I don't do that any more, either.

Recrowning shouldn't be necessary on a brand new rifle, that's for sure. But - in conjuction with a couple of inches taken off the barrel - it sure can help some of the old military clunkers shoot better (just finished this with an old Turk).

I've seem some articles in various magazines where the author deliberately damaged a rifle crown, shot for some groups, then recrowned and shot again. Mind you this was deliberate damage to the crown, but the results were pretty dramatic.

If you can't see any damage, then no, that isn't something you necessarily need to do.
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Old 10-03-2004, 09:42 AM
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Just to be preverse.

IF you are going to clean a rifle wrong (no bore guide, filty grit crusted rod, letting the rod grind against the rifling) then clean it from the muzzle. You'll evntually ruin the last inch of so of barrel, but you can cut it off, recrown, and get back to normal.

If you are going to clean wrong from the breech, and ruin the chamber/rifling lead, then the only cures are (1) a new barrel (2) de-barreling, cut off the chamber, re-thread, rechamber, and rebarrel.

Muzzle loaders are by definition loaded and cleaned from the muzzle...and old ones nearly always show some wear even with a wooden ram-rod being used (wood holds grit just fine). Real old well used ones will show sight placement/stocking changes from the number of times it's been cut off and recrowned.

have had enough rifles and pistols come through taht have improved greatly when the dinks and dents on the crown have been removed that I've never tested deliberate damage. Do have a beater .22LR that could stand the test before shortening it...may just run one to see how little damage is need to be detectable on the target.
------
If you run into my first Garand, will find an odd looking barrel. Rifling was good, but the muzzle rifling was worn from all those cleanings. Hadn't the $ to rebarrel, so counter-bored it back 1/2"....from the front, it looks like a .375" bore, but that extends only for .6". Proably not the best possible way to cure it, but it was cheap...and it shot much better with that deep-recessed step-crown.

Last edited by ribbonstone; 10-03-2004 at 09:51 AM.
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  #5  
Old 10-03-2004, 09:47 AM
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Had to cut a 742 Remington to 18" to remove muzzle wear from cleaning from the muzzle. When it came in the shop, it had a hard time keeping a bullet on the target paper at 100 yards. New cut and crown job and the carbine would keep them in a nice group (1 1/4" - 1 1/2") at 100 yards. the first 1 1/2" of bore was pretty well worn away when the gun came into the shop, so in my opinion muzzle damage definitly affects bullet preformance. Back in the late 50's and 60's when military surplus guns were plentiful at reasonable prices, the ones with worn muzzles went pretty cheap. Before sporterizing we used to fire them with original length barrels, then again after completion, and found a great deal of improvement. Most would shoot 1 1/2" - 2" groups at 100 yards, some would do as good as 3/4" to 1" groups.

Lee L.
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  #6  
Old 10-03-2004, 09:56 AM
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Lion: If you must clean from the muzzle, at least get a stainless steel non jointed cleaning rod and use a bore guide. the stainless will not pick up grit like aluminum or brass. All of my cleaning rods are full length drill rod.

Lee L.
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  #7  
Old 10-03-2004, 11:10 AM
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Another consideration for cleaning from the muzzle is to use a product like Wipe-Out bore foam. I can clean my Savage 99 with about 3 or 4 passes of a cleaning rod, and that's a whole lot less than is needed with traditional bore cleaning products. The stuff is a real windfall for lever gun shooters....
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  #8  
Old 10-03-2004, 01:20 PM
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Bought some bore foam last month, and was supprised at how easy it was to clean up the bore on an old 1893 Marlin 32/40 Sporting Carbine the wife found for me. The bore looked like a mirror after four passes.

Lee L.
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  #9  
Old 10-03-2004, 07:28 PM
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Thanks for all the feedback. All my guns are in good shape so I don't think I'll be messing up the crowns just to see the effect. And, they all have good accuracy, or at least as good as I can shoot. A few are at least 30 years old, and I'm the original owner, and all have been mostly cleaned from the muzzle, so I guess I'm either lucky, or the minor stuff isn't visible and not an accuracy for me. I'll probably be a bit more particular in the future, but I don't think I'm gonna put too much extra effort into something that isn't broken.

Of course, I've run into a few folks over the years that say one thing, but the words don't equate to what their brain is thinking. I'm sure some folks just pound away at cleaning their guns, and think they're being careful and knowledgable about the whole process. Kinda reminds me of this friend I had back in the early 70s who though it was neat that I was handloading some rifle cartridges with a Lee Loader. I showed him how simple it was and demonstrated the process. He went straight out, bought a loader for his .38 pistol and commenced to reload. Knowing him, I should have insisted on being present because he got to the part on seating the primer and I guess he whacked something pretty good. As he told me, when the primer went off, it blew the primer shaft tool right into the ceiling. I'm happy to say that was his last attempt at reloading. Guess he's the type who also screws up a perfectly good crown without much effort at all.
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