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October 26, 2008
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Well, I have finished my .44 accuracy proofing (to the best of my ability). Steve had asked me to talk a little about crowns and their effect on accuracy. So, I will do my best to portray what I know and have learned through my own experience, the experience of others and what I have read.
Much has been written on crowns and their effect on accuracy, trying to tell you that one crown is the ultimate crown, for a long time and to some extent still is believed by many gunsmiths that an 11degree crown is the ultimate crown (some will not cut anything but it). 11 deg. is a very good crown both performance and aesthetically speaking and has been used extensively to win many benchrest, highpower and countless other competitions. However, why if it IS the ultimate crown would all gunmakers not use it? well as most of you know barrels vibrate, their is an interesting article on this and it has gone into hiding on me, they were testing different crowns on many different barrels and calibers. what they decided in the article is that there is no one universal crown that works best. basically what they found was inconclusive due to the variables involved in conducting that test. Every barrel whips (vibrates) differently, even barrels built on the same day with the same tooling and cut with the same chamber reamer shot differently and vibrated differently. 6mmbr had an article a couple years ago on indexing .22 rimfire barrels to find it's optimum length and to basically "tune" it. Think of a barrel like a tuning fork every barrel has it's certan length that it wants and a certain crown to aid in that tuning. Now the big reason I like Dan Wesson's, we are equipped with the ultimate tuniing tool (factory calls it a barrel wrench). I know IHMSA has heard this before, about sillhouette shooters using torque wrenches to get the barrel nuts to same torque to not change POI, well I'm sure some of those same people conducted some tests to find the optimum torque that shot the best, it's barrel tuning. In conclusion there is no one crown that is the best however crowns need 3 things to be effective
1. Must allow perfect (or near perfect) release of the bullet simultaneously
2. Must provide some sort of protection to the rifling
3. Should direct gasses away from bullet so as to not adversely effect the bullet's flight
As long as it does those things there is nothing wrong with any crown. Don't let me or any other gunsmith try to convince you that one crown is better than another because it is not true.
this is the crown that I put on my Dan Wesson's it is 25deg. from perpendicular, I have had very good luck with this crown so far. It is functional and pleasing to look at, I tried the 11 deg. and it didn't look right to me so I kept playing until I got to 25 and that looked good to me and since then it has become my "sandard" crown for Dan's, every Dan that I have given this crown to has improved in accuraccy.
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This next crown is a standard flat crown on a Colt Python
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this is a phot from Lbruce of a "stepped" crown
October 26, 2008
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these are pictures of the targets that I shot with my .44 the first one is: on the left as I received the gun, the right after trigger work. Now I will make the statement that these were fired at 25 yds rested and I do not shoot guns with bad triggers well at all.
next is, left after trigger job and right after recrowning/trigger job (yes I threw one on both targets) You'll notice that it really has not improved it greatly, honestly the .44 did not need to be recrowned it was even and worked fine, but it does show some improvement with no other change and I enjoy doing the work.
Range Officer
Range Officers
Dans Club
February 9, 2009
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Superdan,
very interesting article. I knew nothing about barrel crowns till now. Do you customize your barrels on a lathe? How do you measure the degree?
A man cannot have too many SuperMags
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Moderators
January 24, 2009
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Thanks for the interesting & informative writeup.
I've got a couple questions...
1) Do your crowns have sort of a rolled edge, or are they a straight 25º angle? Hard to tell from the pic.
2) There's quite a difference in those first two trigger job targets, did you shoot those in double or single action?
October 26, 2008
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SMF- yes it is done on a lathe, I use a range rod to indicate within .0001 (sometimes I let .0002 get by) so that I know the barrel is rotating concentrically. The degrees are measured on the compound rest of the lathe, mine is actually reading 65deg. from parallel (25deg from perpendicular).
CF- It is a straight 25deg. no radius on the rifling other than some light polishing to remove tool marks, also they are only angled approximately half the distance from the bore to the outside of the barrel the rest of the distance is left flat to keep them pleasing to the eye and to provide a little more protection. I only go about 1/3 of the distance on a 357 SM because of the small bore as compared to the O.D. All three groups were shot rested @ 25yds and SA.
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Range Officer
Range Officers
May 2, 2009
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What speed are you cutting at? any chattering with the crown tool, or are you just using a lathe bit?
I use an old SB 9"
Mike
(amateur lathe guy !!!)
October 26, 2008
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running a little over 400 (lathe jumps from 270 to 418 or something like that) large frame barrel calculates out to about 325. Nothing abundantly special about the tool HSS ground with a little extra side and end relief so I don't rub on the tool when I'm making the cut. I do sometimes use a specially ground radius tool for the radius crown (old style rounded crown) but not always and then I have to go slower around 100. As for your lathe there is nothing wrong with a Southbend, that is actually what I used when I started school. The lathe I'm using now at home is a 10″ Logan. I've seen barrelling being done on a baby Atlas and the gun didn't know the difference shot just fine, the lathe is as good as the person running it. The only thing about small lathes is that you are somewhat limited on the size of work you can do.
Dans Club
March 2, 2008
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superdan, thanks. I'm no machinist, but after I studied your post I really have a better understanding. I'm assuming this is work that a skilled gunsmith can do if I just tell him what degree crown I want?
I've said it before, and I'll say it again:
I am regularly surprised and amazed at the things I learn here, you don't find this stuff very many other places.
I went to a bookstore and asked the saleswoman "Were is the Self Help Section?" She said if she told me, it would defeat the purpose.
George Carlin
January 22, 2008
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Very good topic guys! Thanks Superdan for posting the information. My question is how much are you going to charge DWF members for this service? I know I would be interested.
Range Officer
Range Officers
Dans Club
February 9, 2009
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Steve CT said:
I've said it before, and I'll say it again:
I am regularly surprised and amazed at the things I learn here, you don't find this stuff very many other places.
I could not agree more. We have a lot of fun here and make many meaningless posts at times 
but the information our fellow DW enthusiasts share is worth gold! I have never witnessed such a solid group of dedicated gun guys anywhere else. Thanks Superdan
A man cannot have too many SuperMags
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