Re-crowning

A

amtmn

Guest
In order to maintain accuracy, how often should the crown be freshened up on a precision rifle? For mine, it's a stock Remington tactical type in .308. Thanks.
 
Not being a smarty pants of any type, but what are you using for an "accuracy guage" to determine the rifle is shooting as it should be shooting?
 
i THINK jackie does his chamber at 250, and the crown at the same time.
i hope he will jump in.
 
crown the

Ya Wilbur is kinda right. Typically one would look at the crown with a borescope and or the q-tip drag it cross the crown from inside the barrel looking for burr. When you should recrown is dependent on mostly the ware you put on it cleaning the rifle or setting it on the barrel crown("bad ju ju" gave away my training). A good jewelers loop and light can help to look at a crown other than a good borescope. Examine for how defined the crown and barrel lands look where they meet. Also if you can or a gunsmith could check to see if the crown is perpendicular to the bore by setting it up in a lathe and looking @ runout of the crown. Also slugging the barrel to see if the barrel dia. is good at the crown and not expanding.

Good Luck.:cool:
 
If the rifle shoots well, re-crown it when accuracy deteriorates.

If it doesn't shoot and has the factory crown, I'd re-crown and see how that works out. Factory crowns can be pretty nauseating. Get a jewelers loupe and look at a few.

Keep an eye on your crown at the 6 o'clock position as this is where your likely to see damage caused by cleaning. When the cleaning brush exits the bore, gravity does its thing, and the cleaning rod goes to the 6 o'clock position...along with the brush. When you pull it back, the brush climbs up and over the crown at 6 o'clock. Do this enough, and you'll start to see wear at that spot. My .308 was shooting patterns until I took a loupe to the crown and noted the damage caused by excessive cleaning. A re-crown fixed it right up.

Justin
 
Zebra13 said:
If the rifle shoots well, re-crown it when accuracy deteriorates.

If it doesn't shoot and has the factory crown, I'd re-crown and see how that works out. Factory crowns can be pretty nauseating. Get a jewelers loupe and look at a few.

Keep an eye on your crown at the 6 o'clock position as this is where your likely to see damage caused by cleaning. When the cleaning brush exits the bore, gravity does its thing, and the cleaning rod goes to the 6 o'clock position...along with the brush. When you pull it back, the brush climbs up and over the crown at 6 o'clock. Do this enough, and you'll start to see wear at that spot. My .308 was shooting patterns until I took a loupe to the crown and noted the damage caused by excessive cleaning. A re-crown fixed it right up.

Justin
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Learn to stop that rod the instant it clears the bore.

It has been my experience that the throat will show wear before the crown. I do set barrels back at about 300 rounds, just enough to establish a new throat. I rarely see any crown wear, but I will freshen it up anyway.

If you damage a crown by improper cleaning, i.e., using those long sweeping strokes that allow the rod, and all that crud, to wipe in the bottom lands, don't be surprised to see damage as much as 1/2 inch up in.

Been there, done that.
 
jackie schmidt said:
Learn to stop that rod the instant it clears the bore.

It has been my experience that the throat will show wear before the crown. I do set barrels back at about 300 rounds, just enough to establish a new throat. I rarely see any crown wear, but I will freshen it up anyway.

If you damage a crown by improper cleaning, i.e., using those long sweeping strokes that allow the rod, and all that crud, to wipe in the bottom lands, don't be surprised to see damage as much as 1/2 inch up in.

Been there, done that.
Click to expand...

Jackie,

Interesting comment on the throat wearing before the crown. Randolph Constantine, a columnist back in the day at Precision Shooting, wrote that he cleaned from the muzzle just because it was easier to fix a damaged crown than it was a damaged throat/chamber. All the more reason to spend the bucks on a good bore guide.

Something else that helps minimize crown/throat damage is to clean your barrel when it tells you it needs to be clean, i.e., when accuracy starts to degrade. Way back when, I was taught to clean after every 15-20 rounds, and clean until there wasn't a speck of fouling. I'd bet I single handily kept Shooter's Choice in business for a while. Then I read something that Ed Shilen said, which was to clean your barrel when accuracy starts to fall off, and only clean it to the point where accuracy returns. It doesn't have to be cleaned down to bare steel. I took that advice because it made a lot of sense, and I figgered' Ed Shilen probably knows a thing or two about the goings on inside of a rifle barrel. This approach has worked well for me with my "tactical" rifle, and my live varmint rifles.

I'll defer to you for your thoughts on this as it pertains to bench guns.

Justin
 
Tim Oltersdorf said:
Here is a crowning tip taught to me by Ralph Stewart: Right before cutting the crown take a spare 6mm bullet. Turn it around so the front tip is facing the muzzle. Push it into the bore and give it a couple of light taps with a hammer.

I want to thank Ralph and Speedy both for all that they have taught me. It was an honor and frankly a bit of an adventure knowing them both. Tim
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Tim, and then you moved Ralph to Tennessee where Jeff and I have to put up with him!!

Just a comment or two on crowning;


-If you finish a crown with a bevel or micro-bevel,, make sure the barrel has been indicated closely, in the grooves, before the finish bevel cut. Micro-beveled crowns will wear better/longer than a sharp crown.

-If on a sharp crown, you can feel/see a difference in sharpness between any of the edge, it needs recrowning.

_If you do your own barrel work you will recrown more often.

(My definition of a micro-bevel is a 45 degree bevel that just slightly goes past the grooves-about 0.005"-0.010")


..

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Crowns

I am of the opinion crowns are more important on rimfires than cfires..... that said I like my crowns on rifles smooth and sharp..... however have never actually tested here is a guy who did....
Interesting testing done on crowns..... on LR Hunting " The over rated crown"
 
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