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| One of Us |
In building custom or buying a factory rifle does the type of crown: recessed, tapered, or flat make a difference in accuracy with all else being equal? Thank you. Buliwyf | ||
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one of us |
I will say this.....In my limited experience with crowning barrels....the type has little to do with it. Doing the crown properly is the most important factor. | |||
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| One of Us |
I install a recessed 11 degree crown on everything. Since that style is all I have used from day one, I can't tell you whether it is better than any other shape. I have seen articles written by supposed experts stating that the 11 degree angle is more effective at redirecting muzzle blast away from the bullet than other styles, but I haven't sat down to test the theory myself. What I can tell you, is that the crown I install is as clean and as perfectly concentric as humanly possible, and that every weapon I have used it on, has benefited measurably. | |||
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Moderator |
a recessed RADIUS crown seems to work pretty well... the purpose of the crown is the allow the bullet to exit uniformly.. results speak, right? this is an AB 416 barrel, with huntingcat's crown  #dumptrump 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 |
jeffeosso, What does "radius" mean? I'm guessing a recess could be tapered instead of flat? B | |||
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| Moderator |
you cut it with a ROUND tool, which makes a raised inside cut, 90deg from the bore #dumptrump 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 |
Oh, you mean the kind you make with a brass head wood screw and valve grinding compound with your electric drill  Sorry, I couldn't help myself.  Interestring note about what works best is a quote form one of the Trinidad Instructors. "If your cutomer thinks so then it does" or something to that nature. He applied it to all sorts of things such as what brand bbl., crown type, etc. Idea was most wouldn't be able to wring out the difference between one or the other and if you thought it was better than it probably was for YOU.Thaine "Begging hands and bleeding hearts will always cry out for more..." Ayn Rand "Life may not be the party we hoped for, but while we are here, we might as well dance" Jeanne C. Stein | |||
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| one of us |
I really think the whole crown thing is overblown. I beleive as Bill does-just cut a nice, even, smooth crown and things should be OK. WHat I do is cut an 11° crown and then use a form tool to cut a radius on the outer half of the barrel. THis gives me the best of both worlds- the (theoretical) advantage of the 11° and the good looks of the radiused crown. I cut this crown for the hell of it on a barrel a few years ago and it shot very well. I am sure it had nothing to do with the crown, but I figured I would stick to it anyway. On a target rifle i would not even have a problem with a perfectly flat muzzle. I have seen a few rifles cut so and they really shot. I remeber some gun rage did tests on a rifle where they tried different crowns and then purposefully damaged the crowns and tested for accuracy with each situation. The severely damaged crowns shot to a different point of aim, but accuracy was about equal to the high quality crowns. | |||
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Moderator |
The theory is that flat based bullets shoot better from a perpendicular crown, and boat tails from an 11 deg crown. I don't think that's ever been proven. What does matter is that the crown be concentric to the bore. Recessing is a practical considuration to protect the crown that the smith spent some time dialing his lathe in to be concentric. __________________________________________________ The AR series of rounds, ridding the world of 7mm rem mags, one gun at a time. | |||
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| One of Us |
Excellent comments! Thank you. B | |||
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One of Us |
Anyone in the Houston, Texas area you'd specifically recommend for re-crowning jobs? Wife's .270 WeM has "quit shooting". My great local 'smith is slowing down and I need the rifle ready to go before 2008. Could need a barrel replacement, so could you comment on same area 'smith to do a re-barrel? Thanx! BNagel _______________________ | |||
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| One of Us |
Is that rag still in business? | |||
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| one of us |
Actually, that rag was Precision Shooting magazine and the article was pretty interesting. The writer experimented with shortening the bbl about .500" at a time and made no attempt to square or finish the muzzle. He simply deburred the actual crown and resumed shooting. Group size did not vary greatly but, as Mark said, the point of impact changed. I have experimented, on my own BR bbls., with lapping and not lapping the crown as a final finish. I have seen no affect on the targets. I also have a few BR shooter/customers that have the crown "freshened up" every 500 rds or so. I certainly would not let anything leave my shop without a precisley cut crown. | |||
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| one of us |
I think this is sorta (but not all the way) along the lines of Damascus in dangerous, low numbered Springlfields are gangerous, crooked barrels won't shoot, you must have a synthetic stock, must pillar bed, etc. It seems obvious and when it produces good results a couple of times, it gets repeated so often tha no one dares to actually check it out for themselves. I know I have never checked it out. I have no desire to run tests and do my dead-level-best to have an even crown and spend a lot of time on it when barreling an action. But I have shot some nice groups with rifles, and seen others that shot well, and later seen that the crown was obviously out of whack when viewed with the naked eye ball. | |||
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| One of Us |
Thanks eddieharren. I don't doubt that Precision Shooting did an article on the topic, but I'm pretty certain that no respectable rag would have written, or, implied that guns with "severely damaged" crowns would group anywhere close to those with high quality crowns. That statement is false and so I was curious to know if the rag that made that claim, IF, they made that claim, was still in business. | |||
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| one of us |
Malm- It was back in the '90's when I lived in Arkansas. That is all I can remember about the specifics. Sorry. Hey, they keep printing that WSM's loaded to the same pressure as larger cartridges produce more velocity because they are "efficient", wood stocks swell when it comes a heavy dew, cryo "stress relieves" steel and does all kind of magical things that can't be explained, moly is the answer to defying the laws of physics and thermodynamics, BSA scopes are good, tupperware stocks are rigid and good for accuracy and don't require glass bedding, Blackstar barrel are made with voodoo and stomp anything else in the world, the latest bullet does this, the latest action does that, and about a million other things that make even less sense than the BS printed above - yet they keep selling more magazines the next month. Have you ever run a test on various crowns? I already stated I have not and have no time or money to throw after it. Have you ever seen nice groups from crowns that made you want to gag? I have at least done that | |||
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| One of Us |
Writers of magazine articles don't have to be correct, they just have to sell magazines. And no, I have never seen a gun with a damaged crown group worth a crap. Usually by the time I see the guns with bad crowns, bedding etc., the owners are beside themselves. I don't purposely test guns for groups until all the obvious errors are corrected. | |||
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| One of Us |
I read the same article in Precision shooting. I think one of the oldtime writers, possibly Julian Hatcher, did some experimenting with damage crowns and bores with some similar results. Like all experiments, this should be repeated, possibly with more controled variables. | |||
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| one of us |
Malm, I don't recall reading anything about a "damaged crown" in this thread until you brought it up. The original question was about types of crowns. That is, radiused, flat, concave or recessed. | |||
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One of Us |
Saeed did some interesting experiments with crowns.....maybe we can get him to reply here.....I'll send him a PM to wake him up! /////////////////////////////////////////////////////////////////////////// "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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| Administrator |
I think you might mean our experiment with damaged crowns. We never finished that project. In fact I was looking out for the data this afternoon, hoping to get on with it and finish it. We generally do a recessed crown, and that has produced great results. Well, Walter has just said he thinks he knows where that rifle is - he probably hid it in the first place! I will post whatever results we I can find. | |||
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| One of Us |
eddie, it was brought up in the 8th reply by Marc_Stokeld where he writes:
To which I responded: "Is that rag still in business?" Then you posted that it was Precision Shooting Magazine. My problem is with the sentence that I have highlighted in red. That statement is utter bullshit and so I was curious who would have published such crap. Statements like that whether in writing in a magazine or mentioned on a gunsmithing forum need to be challenged or folks who don't know any better will accept it as gospel. | |||
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one of us |
gotta love it. tell it like it is, in times when one needs a rifle, he tends to need it very badly.....PHC | |||
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one of us |
This by the same man that told us how important it was to blueprint an action. Anyone remember? I think testing will confirm the red highlited sentence as correct. | |||
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| One of Us |
Could you please post a picture of the round cutting tool that you use for crowning muzzles, or tell me where I could buy one? Thank you in advance | |||
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| one of us |
wouldn't that be like buying new tires and not balancing them?? I am no gunsmith, but I will tell you when fixing or repairing things in my profession, you do your best to elimninate the things that can go wrong or be wrong, so there is less hassle in the end, its all about happy customers and good work in times when one needs a rifle, he tends to need it very badly.....PHC | |||
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| Moderator |
here's an example on the cheapside www.mcmaster.com 3361A12 i think this is the toolholder 3288A17 RNMG, RNG, RNMA, and RNMP inserts. #dumptrump 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 |
Those aren’t round, and they wouldn’t work on a barrel unless your reground and really narrowed the tip so it could enter the bore without hitting the rifling, right? I was more interested in the round ones you said you used. Thanks again.
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| Administrator |
Well, our resident genius has copme back to inform me that he cannot find that rifle we started the damaged crown experiment on. Walter would loose his heda if it was not screwed onto his neck! However, he came up with what he calls a "temporary" solution! He suggested we sacrifice a brand new BRNO 22 rim fire rifle for this, until he finds the other rifle. This sounds reasonable, as we do have people who prefer to have the barrels shortened, and a sound moderator installed on them. So once the experiment is over we can cut the barrel to the required length, and save it. Any suggestions on what sort of damage we should inflect on the crown would be appreciated. | |||
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| One of Us |
Severe... You know, Bubba stuff. You could hacksaw the barrel at a less than square angle and run a case neck deburring tool in the muzzle to remove burrs. Crown it with a drill bit. Use the tools that garage plumbers would use. | |||
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| Moderator |
sorry, yes, these are round. that is, the carbide cutter is ROUND... please have a read of my post with the target.. HUNTINGCAT's crown. pretty clear about that.
Tell ya what, why don't you get a wholesale tool, MSC, or Rex supply catalog and look at the carbide tool holders. i am certain it'll offer a world of tools. of course, you can take a 1/8 endmill, spot mill a cheapo indexable boring bar, and use the round inserts. jeffe #dumptrump 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’ve used round inserts a bunch to turn or groove a work piece while being fed perpendicular to the axis of the turning material, but they are not designed for plunge cutting into an existing hole (like the bore of a rifle) where they are being fed into the work piece in line with the axis of the turning work. The turning material would be in a constant state of being improperly presented to the cutting face of the tool. maybe we are talking about something other than crowning as I understand it, or maybe I’m just to dense to understand how you are using those inserts to do that job. I’m not familiar with what you call a Huntingcat‘s crown so maybe that’s where I’m getting lost. Never mind.  | |||
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| one of us |
Malm, my bad! I didn't catch the sentence in Mark's post. | |||
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| One of Us |
Saeed, I remember reading you testing on this subject as it was a big surprise but memory can be tricky so I'll hazard a post as to what you did.....IIRC you used a dremel tool to destroy a crown of a rifle that shot particularly well and tested accuracy and every time you tried to make it worse the groups changed none!! In fact your testing IIRC supported this statement which is a hard to swallow statement:
May I suggest the following test for testing.....put the barrel in a mill and mill the crown flat at 0 Deg....then again at 2 Deg and again at 5 Deg and again at 10 Deg to see if there is significant group differences. At least in my mind there should be but we at least can have somewhat controlled experiment if the crown is intentionally botched by a known amount. just a thought here. /////////////////////////////////////////////////////////////////////////// "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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| Moderator |
it's not a plunge cut, which is probably where the communication is breaking down. you take a small round insert, put it on a tool holder, cut from the INSIDE of the bore (it does not touch anything) to cut towards the outside of the barrel. it is NOT a giant radiused muzzle.. it's a radius turned INTO the barrel, towards the outside. just perdactly as if you took a small boring bar and decided to cut a square shoulder from the bore to the outside ... just a little step. sorry, if that doesn't splain it good enough, you'll just need to wait till i have time to post pics. sorry, no you are thinking of a constant cut, rather than a step. that's why it's DIFFERENT doubt it's dense, it' just being used to CUT a shoulder, not plunge huntingcat is a poster
jeffe #dumptrump 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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| Administrator |
OK, I am going to start on this probably tomorrow. After the initial 10 5-shot groups, I will get one of our workshop hands to hacksaw about an inch off the barrel, and will shoot it without deburring!? Next we will debur it with a case neck de-burring tool, and we will take it from there. Walter is thinking of BENDING the barrel. He said he saw a German machine gun with a bent barrel shoot very well! Someone else suggested he bends the barrel in a U shape, and point it down at his balls as he fired it. I would love to see that | |||
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| one of us |
When I built up my 6.5 Swede, the barrel was pitted pretty bad so I bought a take off barrel from somewhere in PA for $20. Still pitted but not as bad. I had to make tools to change it and used masking tape layers to headspace. I had to turn the barrel in a little by stoning the front of the reciever. I cut the barrel to 26" with a hacksaw and filed it flat and even. I used a ball with abrasive to crown it. That rifle will hold 1/2" and better with both the 129 and 140 gr bullets and both hit the same point of impact at 100 yd's. A friend gave me some 100 gr Ballistic tips to try and they also shot into 1/2". I have done gun work forever but without a lot of tools, my work was building muzzle loaders, rifle stocks, small parts and repairs, accurizing, checkering, refinishing and carving. That was my first attempt at major metal work. What I can say is the crown doesn't matter as long as it is perpendicular to the bore and edges are broken evenly. How you do it is just how you want to protect it from damage or for appearance. | |||
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| One of Us |
While you're at it, put a little snow or mud in the end to bulge the muzzle and then see how it groups. You do have snow, right? I read it somewhere... | |||
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| Administrator |
 Ski Dubai is less than a mile from wherer we live. The above is a photo of me trying to ski without too much luck | |||
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| One of Us |
Now if you could just do that while carrying a gun that would be a good test. | |||
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