Barrel Crown
- Thread starter Louis.J
- Start date
JerrySharrett
Senile Member
Is it catching lint off the Q-tip or does it just feel sharp? If it is collecting lint, recut the finish cut with a very sharp HSS bit and cut from the inside out with a fine feedrate.
If it just feels sharp, while it is still in the lathe use the shank of a Q-tip and with the lathe running forward, hold the Q-tip shank at about 45 degrees and "burnish" the edge slightly. Then reverse the spindle and do the same.
If you have a burr of even 0.005" or so and you shoot the barrel, and a piece breaks off, that barrel will not be as accurate as is normally would be.
Some gunsmiths, mostly folks who build hunting rifles use a round head brass screw and lapping compound to remove that sharp edge.
OR, probably the best, with the barrel indicated in the lathe to ZERO runout (as near zero and you can read on the indicator) cut a 45 degree bevel on that right-angle edge. In doing this indicate the grooves, then cut the bevel to where it is just barely past the grooves. This will be about 0.005". This makes a crown that is accurate and less subject to damage than a sharp edge.
If you try to cut a crown with a carbide insert you will probably will end up with some burr. There are only a very few carbide insert edges that are sharp enough to cut a burr free crown. Most carbide inserts have a small radius on the edge and that IMO does not make a burr free crown edge.
D
Dennis Sorensen
Guest
Regardless of the style of crown I always 'finish' my crowns with a piloted 60 degree chamfer reamer... it leaves a very smooth 'edge' to the bore. You can do this by hand and refresh anytime anywhere.
JerrySharrett
Senile Member
Shoot it and see how it does. IF it shoots to your satisfaction don't worry any more. If it does not, I'd put it back in the lathe and recrown.
Frank Green when he was at Krieger taught me the importance of a symmetric crown. I had a barrel that only had a few thousands of a break in one groove, so small it took an about 10X loupe to see it but it wouldn't shoot like a normal benchrest barrel should shoot.
M
Mark2
Guest
This type tool may be ok for a hunter but I don't think you will find any/many benchrest barrels finished this way. Leastwise I've never seen any.
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Dennis Sorensen
Guest
You may not have seen many 'Bench' guns with a crown finished with a piloted chamfer reamer but that is because of tradition not because of a detriment to accuracy. I have seen many.
Louis, I bought my first reamer many years ago from JGS and I have some from PT & G.
Louis, I bought my first reamer many years ago from JGS and I have some from PT & G.
Dennis thank you I thought I was the only one that owned one of these Reamers, I have used it a few times and what a difference it has made. Mine was made by Hugh Hendickson. Used it one time at the range cause I was getting flyers. One well- known gunsmith told me not to be doing that, but I ended up winning my relay and the shoot off. So whenever I have a crown that looks out of shape, from brushing or has a burr. Out comes the reamer.
Joe Salt
Joe Salt
Wayne Shaw
Active member
Regardless of the style of crown, I always pull a 60 degree chamfer using a sharp HSS tool, inside out. Just to break the edge and deep enough to catch the groove.
D
Dennis Sorensen
Guest
Hi Joe,
Shortly after I bought my first 60 degree reamer, I was doing warranty work for a number of manufacturers... CIL here in Canada was importing Anschutz .22 rifles with the CIL name on them. One of the better light target rifles and very popular was the CIL 190. CIL got a batch of them back from owners complaining of accuracy problems. I received them for inspection. The crowns did not look good. I finished the crown by hand with this piloted reamer and that solved the problem. The owners were immediately happy with them. It took maybe a minute per rifle to do this. It is a tool over looked by many gunsmiths and shooters. Some seem to think there is only one way of doing a crown. In fact if it is anywhere close to being square with the bore and burr free it works.
I decided to take the barrel back off and re-crown it today based on Dennis Sorensens crowning method minus the chamfering reamer of which I do not have but I was able to copy it on the lathe with the exception of I will be trying a 45 degree chamfer in lieu of the 60 degree just for experimental sake. If it works I will let you all know and if it don't I will do the same.
My game is shooting plain base cast bullets at the highest level of accuracy that one can achieve and I love change in an effort for improvement.
J. Louis
My game is shooting plain base cast bullets at the highest level of accuracy that one can achieve and I love change in an effort for improvement.
J. Louis
S
Stonewall
Guest
I have a Hart barrel chambered and fitted by a "F.Pindell" that is crowned exactly as Dennis example.
Nuff Said!
Glenn
Nuff Said!
Glenn
E
elmerdeer
Guest
Hi Dennis, do you use any oil when doing the crown by hand? And what is your procedure is it a quick few turns?
Thank you
Elmer
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Dennis Sorensen
Guest
I kind of twist the barrel in one hand and twist the reamer with the other hand - dry... a few times...
If I do it in the lathe I use a tail stock center and keep the reamer from turning with my fingers - dry.
Vary the pressure and you can kind of feel when it is good... stop and take a look...
OK Dennis, I'm very intrigued. If one does a number of calibers, you'd need a chamfering tool that took a number of "rods" to take standard pilots, or have to buy a lot of custom pilots, or, more likely, the sane solution is to buy a chamfering tool in each caliber needed.
I love Hugh's tools beyond words, but at my age, have to settle for a faster delivery time. Anybody in the States more or less stock the these?
I love Hugh's tools beyond words, but at my age, have to settle for a faster delivery time. Anybody in the States more or less stock the these?
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Dennis Sorensen
Guest
My original one was custom made with one cutter with 3 various .22 pilots and then a pilot for every caliber up to .375. The custom part being large pilots with a small hole. I forget the name of the maker but he was well known at the time.
Since then I also have a set of 3 cutters with 3 pilot sizes that match the pilots on your chambering reamers. JGS and PTG can supply these.
Since then I also have a set of 3 cutters with 3 pilot sizes that match the pilots on your chambering reamers. JGS and PTG can supply these.
Greg Walley
Member
We believe through experience and years of testing that a flat 90° crown cut with a sharp HSS tool or a sharp carbide insert of the correct grade will give optimum accuracy.
However, I will say that Dennis Sorrensen sent me a sample of his chamfered cut crown and I inspected it with a SEM several years ago. His method produced a very even and burr free cut.
Greg Walley
Kelbly’s Inc.
However, I will say that Dennis Sorrensen sent me a sample of his chamfered cut crown and I inspected it with a SEM several years ago. His method produced a very even and burr free cut.
Greg Walley
Kelbly’s Inc.
G
gunsmither
Guest
I have used the Brownell 45 deg. Hand crowning tool many times with great results. I turn tight fitting pilots from Delrin tightly fit over the 3/16" drill rod pilot. It works best spun in a battery drill with a short burst and some cutting oil. Cuts a very clean crown.