TFS article about crowns

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Mike H posted this 02 August 2014

tturner53 wrote: I have read and re-read John Alexander's article in the latest Fouling Shot magazine and am still a little numb. How can it be that the condition of the crown really doesn't affect accuracy? His evidence seems unimpeachable but it's hard to believe! And what about all those counter-bored milsurps? Were the old time armorers wasting their time?Try shooting a target rifle at 1000 yards and see how many X's you get.

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John Alexander posted this 04 August 2014

                 tturner53,

I am glad that the article had some effect on somebody although I didn't expect it to make anybody numb. It is always interesting how different people react when presented with facts that refute something they have believed. That is especially true if their belief seemed reasonable and logical like it was obvious that the sun circles the earth not the other way around as Galileo claimed and got himself into a peck of trouble with the Pope who had faith that the earth was the center of the universe. Some folks are happy to learn something new that is completely unexpected and think it's funny and interesting that the truth is sometimes the opposite of what “common sense” would make you believe you. But most people don't have such open minds. More commonly people seem annoyed that something they have believed and maybe even told to others isn't true. They look for ways to discredit the evidence and rationalize it away. Or simply ignore the facts and go on believing what they want to. Faith over facts seems to be common today. This is exactly what us shooters have been doing for the 110 years since Mann showed that it was almost impossible to damage a crown enough to make an accurate rifle inaccurate. On another subject ”€œ have you tried the bullets yet? The little bore match is coming. John

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gnoahhh posted this 04 August 2014

I enjoyed the article very much. I like to see sacred cows turned into hamburger. On the other hand, we aren't off the hook from pampering our crowns when using our rifles, as damage therein does tend to shift point of impact- something that could spoil a hunting trip or match.

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frnkeore posted this 04 August 2014

I'm kinda with you guy's on the crown stuff but, I have this to relate, regarding it and it has confused me a bit.

I re-barreled and chambered a 12/15 Martini (22rf) for a friend of mine in the mid 90's. My standard crowning operation is to just cut the lands at the face of the muzzle at 45 deg with a tiny, carbide boring bar, I then spin the barrel in both directions, using 280 grit emery cloth to take out any micro burrs that may be left.

This rifle had shot a 248 8c (100 yards) in matches at our club (3/4” 25 ring).

He sold it through me to another ASSRA member that does a lot of work with 22rf's and this is what he did after receiving it. Emails copied and pasted.

Frank: If you are talking to Ed. Tell him that initial test shooting was good but not great. I recrowned the bbl. and it is now one of the most accurate .22s that I have. Shot it at 100 yds last week with 10mph quartering winds and shot .4, .5, .4, .6 groups with Lapua CenterX and a BSA 36x scope.

I wrote back and asked him what was wrong with the crown.

His answer:

Nothing wrong with the crown that I could see, however my groups at 50' were not as close as I thought they ought to be (Avg with CenterX was .054 for 20 groups). I decided to recrown the bbl and did so manually with 400 grit, then crocus cloth. Groups at 50' went to .024 for 10 groups and then translated to the small 100 yd groups.

It wouldn't seem that what little he did would make that much differance but, he does a lot of testing with 22rf ammo and I don't really know what to think.

Frank

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Ken Campbell Iowa posted this 04 August 2014

hi frank ... our match 22rf needed a different tuner setting on different days. maybe move the tuner 0.002 or 0.005 inches.

that tuner setting could make a change in group size of 300 %. mind you, even the large groups might be 0.5 moa ... then optimize the vibration ( ? ) ... and the groups went to 0.25 moa. it was not unusual to shoot 10 or 15 shots at 0.2 moa ... ” part of the real group ” .

so maybe it wasn't the crown ... maybe it was cloudy that day ...

we also found that you shoot smaller groups if you shoot the catridges as they come out of the box.. in order ... not one end, then the other end of the box. joe might say we need more data points on that, and also the crown effects.

ken

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John Alexander posted this 04 August 2014

gnoahhh wrote: I enjoyed the article very much. I like to see sacred cows turned into hamburger. On the other hand, we aren't off the hook from pampering our crowns when using our rifles, as damage therein does tend to shift point of impact- something that could spoil a hunting trip or match. You are absolutely right. Good point.

Glad you enjoyed the article.

John

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bandmiller2 posted this 05 August 2014

My pet ox was gored, the crown is something I've always fussed about. Surely the crown must have some sway in accurate bullet placement. Frank C.

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John Alexander posted this 14 August 2014

bandmiller2 wrote: My pet ox was gored, the crown is something I've always fussed about. Surely the crown must have some sway in accurate bullet placement. Frank C. Frank, Sorry about your ox. I suspect we have all fussed about crowns. I once lapped a crown with a brass round headed screw and valve grinding compound three separate times when the first two didn't improve accuracy. I assumed that I had done something wrong the first two times -- all in vain.

I agree with you that it sure seems reasonable that the crown would be important and lots of authorities have told us it is. But it seems to me that after reading the type of damage that can be done to a crown without affecting the accuracy a reasonable person will change their position until a good well controlled test refutes the three findings I quoted.

Common sense is no match for experimental results.

John

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bandmiller2 posted this 15 August 2014

John, if we don't have to have perfect cast slugs and the crown has little effect it must be bore fit that seperates an accurate rifle from an also ran. How would you rate accuracy requirements for our beloved lead. Thanks Frank C.

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John Alexander posted this 16 August 2014

bandmiller2 wrote: John, if we don't have to have perfect cast slugs and the crown has little effect it must be bore fit that seperates an accurate rifle from an also ran. How would you rate accuracy requirements for our beloved lead. Thanks Frank C. Frank,

I certainly don't claim to know what factors are most important. The mystery of cast bullet shooting is what make it challenging but cast bullet shooting doesn't have to be based on blind faith and following rules we've been told or seen in print no matter how long the rules have been passed down.

Aside from the quality of the rifle (barrel, bedding, trigger, stock shape, etc.) and shooting techniques, I'm sure there are several factors that matter and many that don't.

By experimenting I have tried to reduce the list I worry about and no longer do many of the things we are told we should do. I have satisfied myself that they are a waste of time. In addition to not worrying about the crown, I no longer weigh bullets, cases, or powder (if it will measure well), reject bullets with small wrinkles or rounded edges, clean primer pockets, index bullets or cases, worry about roundness of the bullet, neck tension, or concentricity of the loaded round. I may not be right about all of these but until I see well designed experiments to show their usefulness I am not going to waste my time hoping they will do some good.

I think the most important factors to CB accuracy are good bullet design, good bullet/throat fit, uniform bore condition (the ultimate is a combination that keeps the bore condition uniform and never needs cleaning) reasonable bullet hardness for the chamber pressure, and enjoying the hobby. John

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billwnr posted this 16 August 2014

instead of getting a sour shooting rifle, recrowning it and expecting better accuracy I would reccommend getting an excellent shooting rifle of known results, boogering up the crown and quantifying the accuracy loss.

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RicinYakima posted this 16 August 2014

That has already been done; see “The Bullet's Flight” by F. Mann. Difference is little, if any.

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John Alexander posted this 17 August 2014

Bill, Ric is right. Mann was probably the first to check it out right. If you don't have a copy of Mann the parts on trying to ruin a crown are in my article in the most recent Fouling Shot.There have been others who tried to ruin a crown and couldn't -- also in the article.

You can change the zero of the rifle but the groups are just as good as before. I know it seems amazing and of course counter to the conventional wisdom. Some folks just refuse to believe answers they don't like and can't be bothered with the facts. But other shooters have confirmed Mann's work and nobody has disproven his findings in 110 years so it is probably pretty solid science -- and that is scarce in the cast bullet world. John

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bandmiller2 posted this 17 August 2014

John, I knew Dr. Manns grandson that lived on the farm where he had his indoor range not far from where I live. He had many of Manns rifles but had been snookered by a fast talker that borrowed and never returned and was loathed to pull them out. Last time I was by, the old house was torn down and a new one built, I fear the old fella may be living with God. Frank C.

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Uncle Russ posted this 17 August 2014

Scenario; Brand new Remington 700V, .22-250 cal, new Leupold 8 x 25 Varmintor scope. Brand new componenents to reload with. Even primers, powder and bullets. Best 100 yd group just over 1.7 inches. :X

Discovered crappy crown cut on an angle from the factory. On one side the rifling did not even exit the muzzle. The Smith I bought it from recreowned it at the famous 11' target crown and with the right load the rifle shoots, for me .600' five shot groups and most other loads under 1 inch. :-}

Now I am confused. I realize this is not cast bullets but something changed by recrowning. What is your opinion?

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RicinYakima posted this 17 August 2014

Uncle Russ wrote:

Discovered crappy crown cut on an angle from the factory. On one side the rifling did not even exit the muzzle. As Bill Clinton said, “What is “is"?” discussing his relationship with Monica. I think of the crown only as the small angled cut from the bottom of the grooves to the face of the barrel; not counting any sinkings, roundings, et cetera. Your case sounds like a bad barrel cut back to fix the rifling problem.Of course, that is just an opinion. Ric

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John Alexander posted this 17 August 2014

Uncle Russ wrote: Now I am confused. I realize this is not cast bullets but something changed by recrowning. What is your opinion? My opinion is that there may, or may not, be exceptions to every rule. The mutilations that Mann and Marshal did to the end of a barrel were extreme and didn't affect accuracy but there may be some kind of damage that will. It is hard to prove a negative.

On the other hand Ric may be right.

Your scenario makes a good case for it being an exception. However, the usual anecdote involves other corrective efforts along with a new crown and the crown gets its share of credit. John

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CB posted this 30 October 2014

With some trepidation, I have to ask why I shouldn't remove the ding in the crown of an otherwise good looking used gun when I bring it home? I'm unsure what a “perfect” crown is, but I don't feel like I'm wasting my time correcting decidedly “imperfect” ones. I will entertain the notion that they only shoot better because I expect them to, but if that's what it takes -----------. All the circumstances necessary for one certain dragonfly to end up wrapped around my car's radio antenna (yes, it's that old) are mind-boggling, but it isn't uncommon.. Yes, I've read the Dr. Mann book - and nothing in it has been helpful to me in the least. With all that knowledge, how come we still even have accuracy problems? (At least I certainly do.) A friend gave me a perfectly hideous Italian M98 Mauser 8x57mm years ago (La Coruna M98/43?) CB's wouldn't stay on 100 yd paper. Bore looked passable, but had extreme “cleaning rod wear” over the 4” at the crown. Hacksaw, file and square, a bit of brass screw and valve-lapping compound, and altho the visible profile proportions are even more hidious, the old putana is a very decent deer rifle. What am I supposed to make of all this? Intellectually, I can't fault John's conclusions, but “something” is missing.

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Pentz posted this 31 October 2014

Now I'm worried about removing the lube “star” from the crown of my barrel...:wnk:

Match Director

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CB posted this 31 October 2014

This topic includes several references to Dr. Mann, and even more about “sacred cows". For my money, Dr. Mann's likeness deserves to illustrate “sacred cow” in dictionaries. About the only thing in the book that had a useful impact on me was the photo of the bullet fired from one of his super-short barrels, that unquestionably demonstrated bullet upset/obduration after exit. (Frankly, I doubted the theory until I saw that, so I'll partially withdraw my observation that I didn't learn anything useful from the book.) I stay away from gunshows as of maybe 5 years ago, because, honestly, my collection is beyond reason /justification. But now I'm challenged to go look for one with an obviously bad crown, just to experiment with group placement as a result of alloy/heat-treatment changes. (I can't bring myself to applying a center-punch or chisel to one of my existing crowns. “Oh ye of little faith"? ---- Sorry, John.)

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TFS article about crowns

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