In trying to get my 4-MOA .243 Handi-rifle to shoot sub-MOA like the one in the magazine article (I bet that one was randomly picked...) I've used a 45-degree chamferer to clean up the crown. Or did I simply destroy it?
Is 11-degree the holy grail of crown angles or does it matter?
Posts: 612 | Location: Atlanta, GA USA | Registered: 19 June 2000
If you want to have the crown accurate, you must have the operation of cutting the crown in the lathe performed by a qualified gunsmith. Many will argue whether or not you need the eleven degree crown or not on your rifle. Personally, I believe that it is unnecesary at best. At worst, it has the potential of introducing unneeded error into the equation of producing a surface on the end of barrel where the bullet and gases exit that is not square to the boreline. If the crown is cut at 90deg. to the boreline, and then counterbored approximately .075-.100", it will provide a quality crown that should last a very long time, providing that it is not abused in the floorboard of your truck, or in some mud hole. We've been using this system of crowning on countless rifles without excellent results.
Posts: 1021 | Location: Prineville, OR 97754 | Registered: 14 July 2002
Sorry to disagree, but I don't think it's that tough. I have a large lathe and cut most of mine that way, but I've cut a pile of them by hand with really simple tools and they worked fine. In my younger days, I cut off one barrel with a hacksaw, trimmed it with a file and crowned it with a homemade brass lap. It was a varmint rifle and shot like a champ.
I don't like 45 deg crowns, but I think it will shoot OK if the crowning is even and smooth. I think that's the secret. I just bought an Eastern European target rifle with a strange 45deg crown and it shoots the lights out. I have owned rifles with recessed, rounded, 11 deg, 45 deg and straight crowns(?) and can really tell no difference in them.
Shoot the gun and see if it works. If I had a new rifle that was shooting 4 MOA, I don't know that the crown is the first thing I would work on.
Posts: 1238 | Location: Lexington, Kentucky, USA | Registered: 04 February 2003
Sorry to disagree, but I don't think it's that tough. I have a large lathe and cut most of mine that way, but I've cut a pile of them by hand with really simple tools and they worked fine. In my younger days, I cut off one barrel with a hacksaw, trimmed it with a file and crowned it with a homemade brass lap. It was a varmint rifle and shot like a champ.
I don't like 45 deg crowns, but I think it will shoot OK if the crowning is even and smooth. I think that's the secret. I just bought an Eastern European target rifle with a strange 45deg crown and it shoots the lights out. I have owned rifles with recessed, rounded, 11 deg, 45 deg and straight crowns(?) and can really tell no difference in them.
Shoot the gun and see if it works. If I had a new rifle that was shooting 4 MOA, I don't know that the crown is the first thing I would work on.
I've seen poor crowns corrected that caused groups to go from 3.5" at 100 yards to .75". I would say that your crown would be the first thing to look at. Then, of course, your bedding, floating of barrel, mag-box bind in reciever and bottom metal, etc.
Posts: 1021 | Location: Prineville, OR 97754 | Registered: 14 July 2002
Considering the crown is the last thing to touch the bullet, it has to be as flawless as possible. This degree of precision can only be obtained by spinning the barrel in the lathe and cutting from the center out. The crown has to be square and concentric to the bore. The lands must break cleanly at the crown without ANY defect.
Recessed crowns are desired because they afford better protection from external damage. I personnaly use the 11 degree crown for the stuff I do. Others believe that the angle does not matter. This will remain arguable, however, "most" everyone who is into precision shooting will agree, the best chance for accuracy lies in a crown which has been precisely machined on a lathe.
I crown all barrels in my lathe, dialed in on the bore, as good as I can get it. Cut from the bore out, real sharp h.s. tool and let the burrs be handled by the first bullet. But when I think about the energy in the bullet that exits the bore, spinning a quarter million r.p.m., moving at ~3000 f.p.s., I really can't see that a little mismatch in gas escape path really affects anything. I'll bet that the irregularities in the jacket/core and fit between them are more detrimental to serious accuracy. Just my opinion and I'll never know because I try to make crowns near perfect.
Posts: 275 | Location: NW USA | Registered: 27 May 2001
The original question was is the 11 deg crown the "holy grail". I don't believe anyone addressed. I seem to remember reading on a benchrest board somewhere in the recent past an explanation of why 11 deg is used. Whether right or wrong, there was a technical reason ascribed to this. Unfortunately, I don't recall what it was. Does anyone know the actual justification for the 11 deg?
Posts: 1238 | Location: Lexington, Kentucky, USA | Registered: 04 February 2003
Thanks for the replies. All this was done after standard load work-up, and it appears to have neither helped nor hurt accuracy.
Kevin, it was a cylinder/forcing cone reamer with bore pilot.
My rationale was if I was going to take it to a smith for a crown job, it would be no more trouble for him to clean my mistake off than if I had done nothing.
Posts: 612 | Location: Atlanta, GA USA | Registered: 19 June 2000
steve, even if you mess up a crown, you can reim a miniscule amount off the muzzle, and do it again-I've redone a couple of muzzleloaders after messing them up to begin with-PROVIDED YOU HAVE NOT DAMAGED THE LANDS INSIDE THE BORE FOR ANY DISTANCE FROM THE MUZZLE!!
I remember they�re being a test on crowns, and there damage. If I recall the final result was not what every one expected. You should do a search on the subject.
If I remember correctly (always a concern)the idea behind the 11 degree crown was the departure angle of the escaping gas was at about 11 degrees and making the crown the same would reduce turbulence. This seemed to be the kind of theory that many could embrace and the 11 degree crown was used by many. It was soon shown that rifles with 11 degree crowns could shoot every bit as good as those with recessed flat crowns. But no better. Back in the sixties, Winchester's testing showed that a counterbored muzzle, twice bullet diameter and about 5/8" deep, reduced turbulence and they made their target barrels like that for a time. The truth is, a good crown works good regardless of it's configuration. The 45 degree countersink would work fine if the resultant crown was centered on the bore and reasonably smooth. Regards, Bill.
