Crown Questions

[Hammond79]

Just bought a .45 rifle from another number of the forum. The rifle is not new by any means and I intended to do some work to get it into prime shooting and hunting shape.

On receipt, I noticed the crown has some burs and abrasions.

1. Is this going to effect accuracy??
2. What are your recommendations to remedy this?

I deeply appreciate your thoughts and opinions on this.

Thank you.

 

[Grenadier1758]

@Hammond79, the burs and abrasions aren't going to help with on target accuracy.

My recommendation is to smooth the crown. Fortunately, this is an easy fix and requires a few sheets of wet or dry metal cutting sandpaper and one's thumb. Using about 2 to 3inch square patches of sandpaper starting with 200 grit. Hold the paper in the muzzle with your thumb and rotate back and forth 1/4 turns. After about 15 rotations, go to another flat on the barrel and rotate again. Get a fresh patch of sandpaper and continue around the muzzle until you have done the same number of rotations in each position. Cut some patches from the 320 grit paper and do the same. Once you have done the rotations with 400 grit paper, you will have a nice smooth crown and the burs and abrasions will be gone. Accuracy and ease of loading should be improved.

Smooth out that crown.

 

[necchi]

Exactly what @Grenadier1758 said, it's that easy.
You could use a marble, or even one of the ball you have for it, wrapped in fine grit sandpaper.
If you've seen those burs and abrasions,, you'll see how this simple method removes them.
All it takes is TLC,,

 

[Hammond79]

Thank you gentlemen. I'll put your advice to use.

 

[Hammond79]

Well gentlemen I followed your advice and am pleased with the results. The tons of knowledge on this forum never fails to astound me.
I used a .490 ball since I don't currently have any .45 balls.

Next stop on the journey will be to run a green scotch brite pad down the bore a few times. Then a new nipple and clean up/replce the powder drum. Slug the bore and get the correct size balls before hitting the range for load development.

After pictures attached.

Thank you again

 

[necchi]

Good on ya,
It's hard to tell from your photos, but ya gotta be careful. Make sure each of those lands has the same "finish" at the muzzle.
I'm looking at the 3rd photo,, and that one land is smooth at the muzzle,, the ones on each side still have a straight finish,
Try to make them all the same,
Rotate the barrel as you rotate the sand paper

 

[Hammond79]

Good on ya,
It's hard to tell from your photos, but ya gotta be careful. Make sure each of those lands has the same "finish" at the muzzle.
I'm looking at the 3rd photo,, and that one land is smooth at the muzzle,, the ones on each side still have a straight finish,
Try to make them all the same,
Rotate the barrel as you rotate the sand paper

I believe that photo is a little misleading due to the use of the flash. Obviously it's a delicate process but I'll go back and put a critical eye on each land.

Thanks again for your help

 

[M. De Land]

Just bought a .45 rifle from another number of the forum. The rifle is not new by any means and I intended to do some work to get it into prime shooting and hunting shape.

On receipt, I noticed the crown has some burs and abrasions.

1. Is this going to effect accuracy??
2. What are your recommendations to remedy this?

I deeply appreciate your thoughts and opinions on this.

Thank you.

What needs to be understood about barrel crowning is that they need to be cut square to the bore axis to begin with and all nicks, dents and inside land corner wear be removed for best accuracy.
You can remove all the imperfections on the crown face and make it shine like a new penny but if you neglect the inside corners of the land ends it will not be a finished job. The end of the lands get lapped off by cleaning and loading rod abrasion if a muzzle protection devise is not used at loading and cleaning.
Fiber glass loading and cleaning rods are a nemesis to any good barrel crown and should be relegated to the trash can.
I can't think of a more important barrel part influencing accuracy or lack there of than the barrel crown.

 

[M. De Land]

Well gentlemen I followed your advice and am pleased with the results. The tons of knowledge on this forum never fails to astound me.
I used a .490 ball since I don't currently have any .45 balls.

Next stop on the journey will be to run a green scotch brite pad down the bore a few times. Then a new nipple and clean up/replce the powder drum. Slug the bore and get the correct size balls before hitting the range for load development.

After pictures attached.

Thank you again

For your education advancement and not a put down, note the center picture of the shine (wear marks) down the edge of the land corners mostly on the left side. This is loading rod wear from not using or improperly fit down bore muzzle protector. This wear will not be even around the bore and will promote inaccuracy eventually.
This is why it's not just dents and scratches in the top face of the crown that needs attention but also the down bore corners and edges of the crown area.

 

[2 shots]

brass muzzle laps are cheap and keep things even . check em out.

 

[waksupi]

Shoot it before you mess with it.

 

[Hammond79]

For your education advancement and not a put down, note the center picture of the shine (wear marks) down the edge of the land corners mostly on the left side. This is loading rod wear from not using or improperly fit down bore muzzle protector. This wear will not be even around the bore and will promote inaccuracy eventually.
This is why it's not just dents and scratches in the top face of the crown that needs attention but also the down bore corners and edges of the crown area.

Thanks, the rifle is new to me but I'll definitely use a bore guide going forward

 

[hanshi]

Polishing the crown of the rifle has more benefits than simply easier loading. You can now use heavier (within reason) patches - I use .024" canvas and the fired patches are reusable. It won't tear the patches now when you short start the prb. I call it a "tight" load but snug is a better description since I easily seat the loads with the underbarrel wood rod. I've found the heavier the patch the more accurate the load. There are other patching materials that work well: pocket drill, denim, canvas duck and even matress ticking goes about .017" or so.

 

[Hammond79]

Polishing the crown of the rifle has more benefits than simply easier loading. You can now use heavier (within reason) patches - I use .024" canvas and the fired patches are reusable. It won't tear the patches now when you short start the prb. I call it a "tight" load but snug is a better description since I easily seat the loads with the underbarrel wood rod. I've found the heavier the patch the more accurate the load. There are other patching materials that work well: pocket drill, denim, canvas duck and even matress ticking goes about .017" or so.

Already have some denim and pillow ticking patches ready to try.

 

[longcruise]

I have a new unfired barrel that has extremely out of whack crowning. I may have to contact Joe Wood for the tool that can fix it.

 

[M. De Land]

I have a new unfired barrel that has extremely out of whack crowning. I may have to contact Joe Wood for the tool that can fix it.

A perfect crown can be accomplished with file work alone from a skilled, patient craftsmen but the lathe, mill or crowning tool just make it much easier and faster.

 

[M. De Land]

Thanks, the rifle is new to me but I'll definitely use a bore guide going forward

Here is a couple of photos of my 36 inch loading rod and down bore brass muzzle guide I made probably 30 years ago, It is one piece rod stock of 5/16 diameter and a 1.5 inch polycarbonate ball. The jags and muzzle guide is simply switched to what ever caliber I'm shooting.
The cord is used to secure it to the front sight so it won't slide out. I don't ever leave a patch down bore even if lubed. The down bore muzzle protector/guide is a loose slip fit into the bore to accommodate a bit of fouling.

 

[IanH]

Actually, a perfect muzzle face and crown are done on a lathe after the barrel has been straightened or verified to be straight and then set up through the headstock of a lathe with a 4-jaw chuck inboard and a matching "spider" or "cat's paw" on the outboard side so that the barrel can be indicated perfectly true to the bore centerline on both ends via test indicator and close-fitting pin gauges.

However, in most cases the skilled use of a file and brass laps suffices.

If it's really hosed, squaring and coning will fix it.

 

[necchi]

and coning will fix it.

I was wondering when someone would mention coning,
Works for me,
But the OP "HAS" improved the muzzle on his rifle with the simple techniques shared here,,
Dissecting further is for those that hunt the elusive X.

 

[M. De Land]

Actually, a perfect muzzle face and crown are done on a lathe after the barrel has been straightened or verified to be straight and then set up through the headstock of a lathe with a 4-jaw chuck inboard and a matching "spider" or "cat's paw" on the outboard side so that the barrel can be indicated perfectly true to the bore centerline on both ends via test indicator and close-fitting pin gauges.

However, in most cases the skilled use of a file and brass laps suffices.

If it's really hosed, squaring and coning will fix it.

That is the theoretical method of barrel centering work but the reality is that no bore is ever perfectly straight nor has a perfect zero in run out. These are two entirely different things as is bore diameter uniformity. Good barrels will be with in .0004 in this regard unless hand lapped closer. You can feel a ten thousands or two when hand lapping with poured and charged lead slugs. Best grade match barrels are not mechanically straightened either they are bored as straight as possible or rejected. If one can get under .004-.005 run out in 30 inches that is about as straight as it gets from what I have read.
Also a barrel plug gauge has to have a few tenths of clearance to fit into a bore and the bore must be even for a meaningful dial indication on the gauge for a center.
I have to do all the turning, threading , crowning and chambering between centers in a steady rest in my lathe as the head stock hole is not large enough but it is just as accurate if not more so when accomplished correctly.
One can dial indicate both ends of a barrel and adjust as close as the run out will allow then turn the lathe on in slow rotation while looking down the bore that can look like a jump rope inside and yet be straight on the outside with the end holes on as close center as possible.
Deep hole boring is an art form and is the heart of any super accurate barrel as everything from there on out is based on and depends on how even and straight it was bored. This will effect reaming and what ever form of rifling method that is used.