The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Gunsmithing Rifle Accuracy: Crown Type?Go | New | Find | Notify | Tools | Reply | |
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| One of Us |
Can’t wait to see some pictures because I am having a really hard time visualizing this procedure. What size (diameter) round insert are you using? | |||
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Moderator |
don't know how to make it clearer. imagine a step cut shoulder, that's square.. here.. think of if you where turning a reloading die for an HH brass, with a boring bar... "see" the little cut made for the belt? nice little square step. make that round. so, until i take a pic and post it, this is my last post on the subject. I believe one could read what is posted and understand. Sorry, out of "wantu" today jeffe opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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| One of Us |
I know what a step shoulder is but I am having a hard time understanding how you cut one on a muzzle with the tool you suggested. If they made round inserts small enough in diameter to do a facing cut across something the size of a rifle barrel muzzle I would think you’d be better off just using a regular facing tool with a slight radius on the tip. I guess I’ll just have to wait for your pictures to clear up my confusion. Thanks for your patience. | |||
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Malm always hates it when I post Saeed's original experiment. It just shows what myths are made of. Saeed's Experiment Larry "Peace is that brief glorious moment in history, when everybody stands around reloading" -- Thomas Jefferson | |||
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What are you talking about? | |||
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| Moderator |
it's not ACCROSS it's small enough to cut a step. liek 3/16diameter... with is 3/32r
does the same thing, and can be done that way I guess I’ll just have to wait for your pictures to clear up my confusion. Thanks for your patience.[/QUOTE] opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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one of us |
QUOTE]Originally posted by larrys:It just shows what myths are made of. Saeed's Experiment[/QUOTE]
Seems once again we have a conflict in opinion verses tested data. | |||
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| One of Us |
Boy, now you really have me confused. Unless I missed the one you’re talking about the smallest round cutters in the link you posted are a half inch in diameter. How do you cut a 3/32†radius with a half inch diameter round cutting tool?  | |||
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| Moderator |
I give up. you are either being purposely difficult or you don't get it. it's not my malfunction if you dont' understand, I am sorry. get a catalog (i have repeated where), look up the various cutters available, as i OBVIOUSLY can't answer your questions, or, more specifically, don't have the patience to lead you along the way. how would you cut a 3/16 dia groove into the face of a turning 1" aluminum barstock? now, do that with a boring bar. the end/.. it's really pretty simple jeffe opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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| One of Us |
No one is conflicted but you. Unlike you, my comments are based on actual experiences. I freely share my time with members of this forum in an effort to help those who are intertested solve some of their problems. I don't give two shits about you, or, what you think. My interest lies in those I can help, not those who are beyond help... | |||
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| One of Us |
Wow, I was just trying to learn something new that I was unfamiliar with. You said that you used a round cutter to cut muzzle crowns and when I asked about it you directed me to a web site and gave me the part numbers for the cutters. I looked them up and according to the specs the smallest one they have is one half inch in diameter. That is way to large to do what you said could be done with it, so I just asked for some clarification so I could understand how you did this with the tool you said you used. If you made a mistake, or mis-spoke all you had to do was say so and that would have been that. Obviously I have struck a nerve here. Sorry about asking questions concerning things you claim to have done. Your quote: “At times, it is amusing to read "opinions", if only to recognize the experience of the poster†That part of your posts I understand perfectly and can say that I totally agree with it after this exchange with you. Have a wonderful day. | |||
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| one of us |
fyj, welcome to the world of gun guru jeffeosso , he lives up to his quote very well.  “At times, it is amusing to read "opinions", if only to recognize the experience of the poster†| |||
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one of us |
on jeffs sig its says something about we band of bubbas, sounds like he living more up to that than the quote you mention  in times when one needs a rifle, he tends to need it very badly.....PHC | |||
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One of Us |
Thanks for posting that larrys...I remember reading it a long time ago.....and it was very surprising as most would assume the crown was very critical. In all honesty, it's so easy to make a "perfect" crown that one just does it and never gives it a thought. Saeed's experiments do, however, suggest that maybe the crown can be damaged without harm to accuracy.....or, just because the crown is dinged is no reason to immediately fix it if the accuracy isn't lost. It has to make one wonder how many myths he is working with every day! /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
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I hope my input helps and does not make things worse. First of all I am not a gunsmith or even close to one but I have been experimenting with guns for a long time. For the last decade or so I have been re cutting crowns on rifles that would not shoot well after many other of the usual things that we do were tried. At first I started using a brass screw and grinding compound but then revered to a tapered grinding wheel as provided by Dremel. I spin the tapered wheel in the crown from zero up to low rpm and back to zero with a variable speed hand held drill. On every crown that I have done accuracy improved in a dramatic fashion. The last one was a formerly new Kimber 8400 Montana in 270 WSM. I could not find any real defects before I started on each crown. I used only a magnifying glass. On the crown shown below which is on a 264 WM Westerner it did not work on the first cut which was very shallow and I ripped the very deep version you see in the picture below that I call a Mauser crown.  Join the NRA | |||
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| One of Us |
Regardless of the results of those well meaning tests mentioned here, that has been my experience as well. | |||
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| One of Us |
I have tried all different configurations of crowns on many BR rifles. It don't make any difference. I want a crown that is perpendicular to the bore with a sharpe edge. I use a very sharp cemented carbide tool that has a chip breaker ground into it so all the angles from the tip are sharp. I do not lap my crown! Butch | |||
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| One of Us |
Those test photos are interesting, but I have some observations that I haven’t seen mentioned. So for whatever they’re worth here they are. My apologies up front if I’m stepping on any toes or ruffling any feathers. 1. The picture of the crown prior to damage being inflicted shows a pretty rough surface. It appears to have been done by a hand turned cutter that was chattering or something, or someone used an improperly sharpened bit and some bad technique to cut it on a lathe. Notice the overall rough surface, ridges and rings. 2. The angle of the picture doesn’t really allow you to see if the crown was cut concentric and perpendicular to the bore or not. 3. The “before†groups sizes ain’t really nothing to write home about, averaging just barely under MOA with several bullet weights shooting over MOA. If I was doing such a test (which admittedly I’m not) I would start out with known entity. A real accurate tack driver with a perfectly executed crown, then start the damage experiment from there. Hell, if you’re starting out with a rough, non concentric crown, and a rifle shooting those size groups the “damage†your doing might actually be helping to fix it!  | |||
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| Administrator |
This was a standard factory rifle, and what we wanted to find out was the effect of a damaged crown would have on its accuracy. Please bare in mind we are talking about practical hunting accuray, not bench rest. We have already started shooting the 22 BRNO rimfire at 50 yards, and I will post the results as we go along. | |||
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| One of Us |
I agree with fyj, I too would think the best place to start any accuracy test would be to begin by cutting a fresh crown to provide a base line from which to compare future group results as the muzzle damage increases. | |||
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| Administrator |
malm, I will do that in due course. I will shoot the rifle as it came out of the box, do some damage to the crown, use a hacksaw to cut the damaged part off, use a case de-burring tool to remove any sharp edges on the new end. damage it more severly, shoot; put in the lathe and cut that part off, shoot it again, and so on. | |||
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Don't forget to take it skiing.  A lot of guns that come through here with muzzle damage are the results of folks taking headers off their ATV's and plugging their muzzles just enough to buldge the very end. The type of bulge I'm refering to is one that is difficult to see because it is so close to the edge of the crown. | |||
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Saeed, I am wondering if there would be much change in, say doing the same tests with a 30 caliber weapon insted of the 22 LR. Not that I want to see you destroy a 30 caliber gun but just thinking about the Velocity and the effect between a 22LR and a 30 cal. | |||
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| Administrator |
We have plenty of 308 rifles here that we change the barrels of. I might just take one and do a similar test on it before discarding the barrel. Again, I would like to stress that we are only interested in seeing what changes occur on a hunting rifle, with normall ammo. | |||
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| Administrator |
malm, Many years ago, I had a single shot 410 shotgun. I did just what you have seen others do. I somehow managed to get some sand into the barrel, and bulged it about 3 inches from the end. My grandfather hacked that part of, and that shotgun was almost useless afterwards. We never knew anything about chokes then. | |||
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| One of Us |
Other than the looks, you would have probably been just fine leaving the bulge where it was. Years ago that would be referred to as a "Jug" choke. | |||
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one of us |
Saeed, I second the thought to do the test on something other than a 22lr. The 'theory' is that the escaping high pressure gases tip the bullet upon exit from a damaged crown. There isn't much high pressure gas left in a 22lr. To maximize the effect pick a worst case scenario, something like a 7mm Ultramag or 30-378. The more overbore, the better. If you don't see a significant effect from a bad crown from that, you can make some real conclusions. The more accurate the rifle, the better also. Finding an extra .1" from a 1.5MOA rifle is very hard, finding it from a .2MOA bench gun is much easier. I know, sacrilidge in destroying a benchrest class barrel, but all in the name of (pseudo) science. Sounds like fun in any case! Believe nothing, no matter where you read it, or who said it, unless it agrees with your own reason and your own common sense. | |||
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I wasn’t trying to start any trouble, or insult anyone, was just voicing an opinion that such tests might be more valuable by starting with a well crowned truly accurate rifle. I didn’t know that this criteria would automatically exempt hunting rifles. It was just that after I looked at the pictures of the crown and saw the size of the groups that were fired I thought that it would have been interesting to start by redoing the crown to see if that possibly would improve the accuracy, then start damaging it to see if the now known accuracy would start to fall off, stay the same, or maybe even improve. As malm and others have stated they have personal experience with rifles that shot much better after being crowned properly. As far as any of us know at this point perhaps a poorly done crown is even worse than a damaged crown in some cases. Interesting stuff either way. | |||
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| One of Us |
That's an intereting thought. Maybe the guns that show improvements to accuracy when one purposefully damages a crown, does so because the original factory crown was worse. Now that, I could believe.  | |||
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