"Muzzle Crowns" Educate Me Please

mkrainc

mkrainc

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To make sure to not hi-jack another thread here, I have a question regarding muzzle crown angles.

In the thread mentioned, one poster mentioned using a 60 degree cutter. The crown on my heavy barrel has a 10 degree target crown. What are the advantages/dis-advantages of the different angles.

I ask because I just machined a barrel for my 99E and had to re-crown the muzzle. I put a 10 degree crown on it. Did I just make a mistake?
 
My opinion
If you can machine the muzzle at exactly 90 degrees, that is acceptable and will work fine. The hazard is that it can be easily damaged as it is right out "in plain sight".
As to angle, almost any angle will work, up to about 45 degrees, in my opinion.
The main issue is to be concentric with the bore.
 
Agreed
oldstarfire said:
My opinion
If you can machine the muzzle at exactly 90 degrees, that is acceptable and will work fine. The hazard is that it can be easily damaged as it is right out "in plain sight".
As to angle, almost any angle will work, up to about 45 degrees, in my opinion.
The main issue is to be concentric with the bore.
Click to expand...
 
The crown is actually where the bore edge meets the muzzle edge.The end of the muzzle can be many shapes as seem by different manufactures.Some contoured some at 11 degree some with a step some at 90 deg to the bore.The actual crown is where the muzzle and the bore meet in most instances this should have no burr's or machining marks to disrupt the bullet as it leaves the bore.This has always been a highly discussed topic Repaired and fixed by many means from a brass screw and lapping compound to a specific bevel completed by a competent smith.Guntech will chime in here with his vast knowledge base.To answer your question I think you are good to after you remove the tiny burr created by your machining method.Check with a q tip to spot any burr.There is a video floating around the inter web done by a fellow that as he progresses through the test he keeps adding damage to the crown and his results seem to show that the pristine crown some strive to get really has no real advantage for the actual accuracy within reason.This wouldn't sit well with some bench rest fellows but the average hunter probably wouldn't see any drastic change.But it is a highly discussed topic as some are bound to post here soon.

https://www.google.ca/search?q=muzz...&oe=utf-8&gws_rd=cr&ei=RQl7V6DMJqawjwSYobK4CA

R
 
I am familure with the making sure there is no burr where the crown and bore meet. This the main reason I will always push a patch through my target barrel and are so careful pulling the rod back out. The rifle in question is a hunting rig, but the same rules will be applied. (I re-read the above post and between Guntech and ronnie01, I now understand the term "crown")
 
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It has been my experience that finishing a crown with a 60 degree piloted reamer leaves a burr free crown that is very smooth and as accurate as it can be.

This is a recessed target crown but the piloted reamer can be used to finish any configuration of crowning. Smaller picture is in better focus...
heavy308crown-0.jpg
titanium700crown-0.jpg

60degreereamer-0.jpg
 
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OK. The picture of the recessed target crown spelled it out for me. The 60 degree portion is only to finish the bore edge. Thank you Guntech and everyone for your replies.
 
Guntech, that's a nice crowning tool, especially with that interchangeable pilot.

I have threatened to purchase one of those several times when chucking up a barrel in a four jaw chuck and squaring up the muzzle/crown to the axis of the bore with the aid of a spud. The time that little tool would save might just be worth it but I need a set of trammels first and they have certainly gone up in price.

I saw that video and read an article by PO Ackley on crowns and their effect on accuracy. Certain types of damage will have different to no effects. Ackley talked about a barrel they cut off with a hacksaw at a 45 degree angle and cleaned the burrs off the muzzle with a round file. The barrel shot as well as it had before with a square and properly finished crown. If memory serves it was an 8mm Mauser bore on a 98 action and was quite accurate until they did their magic to it.

Many military depots counterbore damaged barrels at the muzzles regularly or at least they used to as evidenced in some SKS, Mosin, Lee Enfields, Mausers and Springfields as well as others. This is done for several reasons including pull through wear and rust for the most part. I have a RC K98 that came with the last three inches of the bore rusty and pitted and the muzzle face was in the same condition after the grease was removed. The darn thing shoots very well but it does foul quickly which is far more detrimental to accuracy.

Guntech, that is a very nicely done crown. The recessed crown is my go to profile as well. A well done crown is just a great looking finishing touch on any rifle.
 
Yup..... Not bad for an SKS at all.....

I have used the brass screw and polishing method on cooeys and they shot ok for what they were too.....

But considering OP is talking in thousands of an inch and degree of pitch, I am going to assume he isn't shooting an SKS or a Cooey..... Lol
 
Superbrad said:
Yup..... Not bad for an SKS at all.....

I have used the brass screw and polishing method on cooeys and they shot ok for what they were too.....

But considering OP is talking in thousands of an inch and degree of pitch, I am going to assume he isn't shooting an SKS or a Cooey..... Lol
Click to expand...


IMHO the only important part of the crown is where the rifling ends. I can understand certain types of damage causing accuracy issues but they are not nearly as many or frequent as many would believe. The thing is, a nice crown such as those pictured here definitely add some class to the rife.

As for Cooeys, they were designed to shoot STANDARD VELOCITY ammunition. They are OK with the hotter stuff but really shine with what they were designed for. I have a couple of Cooey single shot rifles that will consistently shoot groups under 3/4 inch at 100 yards. Off the bench of course on a cool still morning. Those rifles were built to incredibly tight standards. In those days, accuracy in a 22 rimfire was a big deal. Many schools/clubs/businesses etc. shot competitively and often. In most cases they had municipal matches and the outcome of those matches was taken seriously. Times have changed and many of those fine old rifles languish because they aren't as tactical looking or ###y as the newer offerings. To bad, my go to gopher rimfires are a Cooey single shot and a bolt action repeater with the under barrel tubular magazine. They are both scoped because of my aging eyes and have had many thousands of rounds through them but they still shoot better than I can hold as long as they're fed standard velocity ammo.

There was a time when people paid a premium price for the high velocity and min mags, now we pay the premium for the standard velocity offerings because the demand is low and they don't make as much of it.

If you haven't already, try some standard velocity ammo in your Cooey. When you shoot it, do it seriously and take care. You may be surprised at what you really have. By the way, Cooey rifles really like to be clean. Not that you don't but so many people just shoot their 22rf rifles and put them away without running a couple of patches through them.
 
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