Glad to see you back on the Board and earning your keep by answering all kinds of questions!
I remember you mentioned all of your rifles had a double crown on them. Would you please post a photo and/or a drawing of that double crown? I have already ordered a 1 in 11" twist, 3-groove, super match grade SS Pac-Nor barrel and will probably have it installed on my Savage 12VLP early this coming fall. I want my gunsmith to do the double crown on that barrel. I would like to be able to explain it or show him what I want.
Thanks in advance for any help you can give me. Once again, I'm sure glad to see you posting on the Board again.
Friend Silverfox: On that crown, I'm unable to dig through my safe to haul out any varmint rifles, as I'm Dr. limited to no lifting more than 5 lbs right now, so I'll explain it the best I can.
First off though, credit for this crown design comes from my friend and Master Riflesmith Darrel Holland here in Oregon (Holland's Shooting Supplies). It is designed for both ballistic performance/accuracy, ease of cleaning and long crown and brush life.
Many will agree that the 11 degree target crown has the least effect on the base of the bullet with propellent gasses as the bullet leaves the muzzle (many BR shooters use it). We also all know that we must clean our barrels on a regular basis to maintain peak accuracy, and a bronze brush is a critical component of the cleaning equation. This brings us to the dual angle crown.
Just imagine a standard muzzle cut with the 11 degree target crown. Now imagine a second crown, much smaller, right at the muzzle opening, cut at 60 degrees. This second crown is cut to allow the bronze brush the best entry angle back into the bore to be both easy on the crown itself, and gentle on the brush so as not to bend the bristles too harshly, and give easy entry back through the bore on the return stroke when cleaning.
Using this design, the bullet gets the benefit of the 11 degree crown for the gas effect, giving the least possible upset on the base of the bullet, the 60 degree cut will give noticeably longer "crispness" of the crown at the rifling, and your bronze brushes will last longer for more cleanings.
As some of my varmint rifles made many years ago have 'single crowns' of various designs, I can now say that the dual crown does indeed give the benefits as claimed, and every new barrel I order now is cut with the 11/60 degree crown.
As your new barrel is coming from Pac-Nor, you may just ask them to crown it for you prior to shipping, as they're very familiar with the 11/60 crown, as they're very closely associated with our mutual friend, Darrell Holland. Back in the late 90's, I was shooting PD's in Montana with both Chris from Pac-Nor, and Darrell Holland, and during dinner this subject came up, and since then the 11/60 crown has been sort of standardized for both them and me for our personal rifles.
Hopefully you've got a mental picture of the crown now, but if not, I'll stick my camera into the safe and see if I can get a macro shot of one of them for you.....let me know.
Semper Fortis
Rick in Oregon
NRA Life/OHA/VHA/VVA
Oregon, East of the Cascades - Where Common Sense Still Prevails
RIO, a couple of years ago, the Doc told me not to lift more than 5 lbs. after neck surgery. I asked him how I was supposed to go to the can. He did not think it especially funny, but the nurse did.
"Those who hammer their guns into plowshares will plow for those who do not." Thomas Jefferson
Rick--thanks for the reply. I guess I got the wrong idea on the "dual crown" and thought you said the usual 11º target crown and then at the bore do a 60º and finish it off with a 20º cut from where the 60º quit so the 20º hit the lands and grooves. That last part with the 60 and 20 sounded like it would be impossible to do, and that's why I was asking for a picture--I'm a visual kind of guy
Here's a link to a photo I "borrowed" off the Internet and wonder if this is more like what you are describing?
I had issues with my .17 Rem Pac-Nor barreled rifle throwing bullets willy nilly over a prairie dog town. It would shoot two or three right on target and then one would be 25 yards right and 25 yards or so short of target. I had my gunsmith recrown that barrel and he did the 11º target crown and then did a 60º cut down the bore. I should take a photo of it, but the rifle is in my pickup and I'm too lazy to go get it. However, it dows look much like the photo in the link I listed above.
Thanks again and don't worry about not being able to haul out your varmint rifles. I think I have the idea right in my head now. Take care and get well soon.
SF: The photo shows a 'step crown' with the 60 degree cut at the bore....close to what we're describing. Instead of the step or floorboard crown shown, just imagine a full 11 degree crown with the 60 degree cut at the bore and you have it.
I'll be glad to poke the camera into the safe and shoot one of mine if needed, just let me know.
(When I look at some of my other crowns not cut this way, under magnification I can see the very slight damage the bronze brush causes right at the origin of the rifling with square cut crowns...they still shoot quite well, but the visual damage is evident and I'm sure those rifles would/could shoot better if crowned 11/60 degree. I've got to get another lathe soon....)
Semper Fortis
Rick in Oregon
NRA Life/OHA/VHA/VVA
Oregon, East of the Cascades - Where Common Sense Still Prevails
Rick--here's a photo of my .17 Rem Pac-Nor barrel crown as it looks now. Is this along the lines of what you are talking about? Isee I have lint on the end of the barrel
SF: Well yes, the 60 degree part is correct, but that crown you have there is usually referred to as a step or floorboard crown, and is cut at 90 degrees to the bore.
With the 11 degree target crown, there is an 11 degree cut from the 60 deg crown, all the way out to the outer edge of the barrel for the positive effect it has on the escaping propellent gasses. I'll try to post one of my 11/60 crowns tomorrow. I see I've got three of the 11/60 deg crowns on rifles in the front row in the safe, so no problem taking a macro shot to post without straining my sliced up gutty-whats (a term taken from the Stanley Kubrick movie 'A Clockwork Orange'....been using it for years.)
Semper Fortis
Rick in Oregon
NRA Life/OHA/VHA/VVA
Oregon, East of the Cascades - Where Common Sense Still Prevails
Rick--Sorry I didn't get back here sooner. My wife and I went up to the new Virgil Syverson Performance Center (an outdoor band performing building that was just completed) for the opening ceremony and concert. The gentleman it was built to honor is 91 years young and still directing the city band at concerts each Thursday during the summer in Harmon Park here in Williston.
PLEASE BE REAL CAREFUL when you take the photo. I don't want you to "strain your sliced up gutty-whats" and cause you a setback in your recovery process. OK? Just go easy my friend!!! I appreciate all the help.
PS I have the 11º target crown on my Lilja barrel and that has no step, just the 11º angle from the outside of the barrel down to the crown on the bore.
SF: I found this photo taken of the new 204 Match Pac-Nor 11 twist barrel from when I first got it home.
As it is almost a straight-on shot, it may not show the full effect of the 11 degree crown, but you can see that the 60 degree "brush-entry" crown is right at the rifling, and then the 11 degree crown extends from there right to the full diamter of the barrel.
If this doesn't do the trick, I'll still be glad to poke the camera into the safe and take another shot at a greater angle to better show the 11 degree crown effect. Let me know.
Semper Fortis
Rick in Oregon
NRA Life/OHA/VHA/VVA
Oregon, East of the Cascades - Where Common Sense Still Prevails
Rick--Thanks!!! That picture says it all. I am certain I can make my gunsmith understand what I want now. I'm glad you had this photo on file and didn't have to "strain your sliced up gutty-whats" to show me what the double crown looks like. Thanks again!!
Great picture of the crown Rick and thanks for sharing your knowledge about how the crown helps out. After 50 some years of shooting and being around guns. I'm just finding out how much i don't know being around you guys.
I'm still chuckling! Good one Lee.
