Well I found out this weekend about the importance of crowns. I have just started rebarreling my own guns and have a few under belt. the first three shot like a dream and then I decided to try a different crown on my 300WM... I rebarreled it with a Rock 5R 1/10 twist. It looked great! I took it to the range and could not get it to group better than two inches at 200yds. I was pissed to say the least. I started giving the gun the once over and couldnt come up with any reason it wouldnt shoot better than that. I then started looking at the crown and although it looked great there was just too much crap on it... I decided to take off the barrel and go back a crown that was no so deep and what do you know.. 5 shot group that was .69". Needless to say I was relieved... and I found out even though a crown looks good doesnt mean it will work...
Gunsmithing Importance of Crowns
- Thread starter Westtexan
- Start date
Re: Importance of Crowns
This is the final crown...
The original crown was like this one only deeper and instead of a 45 degree angle, I had about a 60 degree angle...
This is the final crown...
The original crown was like this one only deeper and instead of a 45 degree angle, I had about a 60 degree angle...
Re: Importance of Crowns
As you can see the crown is still clean after a session at the range. The original crown after 30 rounds was filthy....
As you can see the crown is still clean after a session at the range. The original crown after 30 rounds was filthy....
Re: Importance of Crowns
The barrel that was on the remmy before this had the 11 degree crown. Never really shot it much as the Rock was a christmas present...
The barrel that was on the remmy before this had the 11 degree crown. Never really shot it much as the Rock was a christmas present...
Re: Importance of Crowns
Sorry to come off topic, but I keep staring at your avatar KENDA. Its hypnotizing.
Sorry to come off topic, but I keep staring at your avatar KENDA. Its hypnotizing.
Re: Importance of Crowns
What set up did you use to cut your crown?
I'll give you a shiney new nickel if you take the key out of that 3 jaw.
What set up did you use to cut your crown?
I'll give you a shiney new nickel if you take the key out of that 3 jaw.
Re: Importance of Crowns
If you install a muzzle brake on that rifle, like a Badger FTE brake would you have to cut away that crown? Would it screw up your accuracy?
If you install a muzzle brake on that rifle, like a Badger FTE brake would you have to cut away that crown? Would it screw up your accuracy?
Re: Importance of Crowns
I just ran the barrel thru a spider and the headstock, dialed it in to 0 and cut it with a carbide cutter. I just noticed the key! LOL.
I just ran the barrel thru a spider and the headstock, dialed it in to 0 and cut it with a carbide cutter. I just noticed the key! LOL.
Re: Importance of Crowns
If I installed a brake, I would have to cut away some of the crown or cut a different crown... I dont think it would affect the accuracy as long as the crown was cut right. The first crown I cut I think was too deep and created some kind of turbulance which affected the accuracy.
If I installed a brake, I would have to cut away some of the crown or cut a different crown... I dont think it would affect the accuracy as long as the crown was cut right. The first crown I cut I think was too deep and created some kind of turbulance which affected the accuracy.
Re: Importance of Crowns
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Westtexan</div><div class="ubbcode-body"> The first crown I cut I think was too deep and created some kind of turbulance which affected the accuracy. </div></div>
i kind of doubt turbulence from too deep of a crown was affecting the accuracy. not cut perpendicular to the bore or not a smooth, bur-free transition from the bore to the crown was more likely the reasoning.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Westtexan</div><div class="ubbcode-body"> The first crown I cut I think was too deep and created some kind of turbulance which affected the accuracy. </div></div>
i kind of doubt turbulence from too deep of a crown was affecting the accuracy. not cut perpendicular to the bore or not a smooth, bur-free transition from the bore to the crown was more likely the reasoning.
Re: Importance of Crowns
The key is not usually in the chuck.. I just happen to post the one picture where it is.. You are probably right about it not being perpindicular. I wish I had a picture of the 1st crown after I shot the rifle... it was so was covered in black.... thats what got me to thinking something was not right with it.
The key is not usually in the chuck.. I just happen to post the one picture where it is.. You are probably right about it not being perpindicular. I wish I had a picture of the 1st crown after I shot the rifle... it was so was covered in black.... thats what got me to thinking something was not right with it.
Re: Importance of Crowns
Westtexan,
It looks like your doing a good job and learning how important machining can be.
Do you have a 4 jaw chuck you can use next time. The problem with using a 3 jaw is if it not adjustable, your indexing the barrel off the OD of your barrel. You want to only focus on the ID of the bore.
I bet if you dial it in off the bore with some range rods, you would still cut out some runout off the existing crown.
Let me know if you need any help.
Mark
Westtexan,
It looks like your doing a good job and learning how important machining can be.
Do you have a 4 jaw chuck you can use next time. The problem with using a 3 jaw is if it not adjustable, your indexing the barrel off the OD of your barrel. You want to only focus on the ID of the bore.
I bet if you dial it in off the bore with some range rods, you would still cut out some runout off the existing crown.
Let me know if you need any help.
Mark
Re: Importance of Crowns
It is hard with the 3 jaw but I have been working with range rods and working off of the id of the bore.... it takes a while to dial in thats for sure... I am looking for a good 4 jaw to take care of that problem and I have made a spider to for the rear of headstock. That old Clausing sure works great though. Picked it up from a machinist for a $1000 with tooling. It is a learning experience to say the least. I sure appreciate the feedback and the help!
It is hard with the 3 jaw but I have been working with range rods and working off of the id of the bore.... it takes a while to dial in thats for sure... I am looking for a good 4 jaw to take care of that problem and I have made a spider to for the rear of headstock. That old Clausing sure works great though. Picked it up from a machinist for a $1000 with tooling. It is a learning experience to say the least. I sure appreciate the feedback and the help!
Re: Importance of Crowns
I'm running two Clausing 13x40's in the shop and they run extremely smooth and cut very well. You cant beat them.
Mark
I'm running two Clausing 13x40's in the shop and they run extremely smooth and cut very well. You cant beat them.
Mark
Re: Importance of Crowns
Its not the prettiest one for sure but it sure works well. The machinist had just rebuilt the whole thing but never used it. It was just setting in the shop where my buddy works. We split the cost at $500 each. I think it was a good deal and will work better when I can get a 4 jaw on it. I just wished it was a little bigger and had a little more swing on it.
Its not the prettiest one for sure but it sure works well. The machinist had just rebuilt the whole thing but never used it. It was just setting in the shop where my buddy works. We split the cost at $500 each. I think it was a good deal and will work better when I can get a 4 jaw on it. I just wished it was a little bigger and had a little more swing on it.
Re: Importance of Crowns
We had some of those same older machines in gunsmith school along with a bunch of newer Clausing-Metosa 1440's. The little guy you have has drawbacks but is definitely high quality and for a grand I think you did pretty well.
We had some of those same older machines in gunsmith school along with a bunch of newer Clausing-Metosa 1440's. The little guy you have has drawbacks but is definitely high quality and for a grand I think you did pretty well.
Re: Importance of Crowns
You Jersey boys gotta keep your eyes above the waist!
On topic though, exatcly how did you cut the crowns? I hate to be the ass that points out something too easy or common knowledge, but you do know you cut from the bore out, right? I cut a crown once from the outside into the bore and it was a mess. Under close scrutiny you could see the lip left around the crown, and Jim shot it and showed me how much fouling it caused at the muzzle.
Too funny on the chuck key. We mainly run a collet chuck, but when the jaws are on I have to watch myself. Within the first 10 minutes of my lathe lessons I had my butt chewed thoroughly for leaving the key in the chuck.
You Jersey boys gotta keep your eyes above the waist!
On topic though, exatcly how did you cut the crowns? I hate to be the ass that points out something too easy or common knowledge, but you do know you cut from the bore out, right? I cut a crown once from the outside into the bore and it was a mess. Under close scrutiny you could see the lip left around the crown, and Jim shot it and showed me how much fouling it caused at the muzzle.
Too funny on the chuck key. We mainly run a collet chuck, but when the jaws are on I have to watch myself. Within the first 10 minutes of my lathe lessons I had my butt chewed thoroughly for leaving the key in the chuck.
Re: Importance of Crowns
I did cut it from the bore out. I am on the lookout for a good 4 jaw chuck although it would be nice to run collets... Maybe later when I quit spending money on barrels... LOL... I am having fun rebarreling all my guns right now...
I did cut it from the bore out. I am on the lookout for a good 4 jaw chuck although it would be nice to run collets... Maybe later when I quit spending money on barrels... LOL... I am having fun rebarreling all my guns right now...
Re: Importance of Crowns
I think HSS cuts much cleaner than carbide when it comes to crowning. Even then it never hurts to lap it if you're in doubt.
I have to ask...How are you indicating to bore ID without a 4-jaw??? Shimming with something???
I think HSS cuts much cleaner than carbide when it comes to crowning. Even then it never hurts to lap it if you're in doubt.
I have to ask...How are you indicating to bore ID without a 4-jaw??? Shimming with something???
Re: Importance of Crowns
its not easy and its time consuming.... use aluminum shims and keep messing with chuck and the rear spider... Its a pain in the ass but until I get a good 4 jaw it has to work...
its not easy and its time consuming.... use aluminum shims and keep messing with chuck and the rear spider... Its a pain in the ass but until I get a good 4 jaw it has to work...
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