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Crown condition overrated?

This is a discussion on Crown condition overrated? within the Accuracy forums, part of the M14 M1A Forum category; Came across this article where they tested the effects of various damage:

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Old January 28th, 2016, 04:37 PM   #1
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Crown condition overrated?

Came across this article where they tested the effects of various damage:

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Old January 28th, 2016, 05:06 PM   #2
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Years ago I needed a short barreled rifle for a hiking trip in bear country. I took a 98 mauser with a commercial .30-06 barrel and cut it at 16 inches with a hacksaw. Trued the end on a belt sander. It was tack driver. Shot cloverleafs at 100 yards. Go figure.

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Old January 28th, 2016, 07:41 PM   #3
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This sort of goes to the idea that you should know your rifle. I have rifles that should shoot straight, but don't. Lord knows I spent enough on them. I have rifles that shoot fantastic and are cheap and pretty well beat up. It all depends. Having said that, I still would not own a rifle with a beat up crown. I would get it fixed. Maybe on the cheap, but fixed.

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Old January 29th, 2016, 05:02 AM   #4
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Great article and very good info. Thank-you for sharing

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Old January 29th, 2016, 08:23 AM   #5
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Stunning with the mangled crown - I would never ever have imagined that. I am a stickler for crown condition to include lapping with brass rods and lapping compound. I have pulled / cut back barrels for miniscule damage.

The BC variations in the 3 rifles at the beginning of the article is more than likely attributable to differences in twist. Twist rates have a measurable impact on BC and even barrels that are the same will vary - especially button rifled barrels - it is a known issue that buttons tend to slip and the twist is a bit slower than what is published.

Still shaking my head.

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Old January 29th, 2016, 08:55 AM   #6
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I dial the bore at the muzzle before crowning with as much care as I dial the breech end before cutting tenon and chambering, I would have never guess the results from their work.

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Old January 29th, 2016, 09:29 AM   #7
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Interesting indeed. I try to take as good care of barrel crowns as possible. I even cringe when I see someone stick a rifle bore-down on the floorboard of a prick-up, - right into all that grit and sand (I will stick a gun in a pickup bore-down on the floor-mat too but I always pad the crown area).
While I try to protect the crown - I did have one of my match rifles slip and slide muzzle down on a concrete floor one time. (ever notice how when you drop a rifle it either hits on the sights or crown - and when you drop a pistol it seems to always land on the sights). Anyway, the crown got scuffed, not as bad as the one in the article but scuffed to make a heart skip a beat. Subsequent testing revealed that the scuff had absolutely zero impact on the accuracy of that match rifle. But, I will still do all I can to protect the crowns of my rifles.....

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Old January 29th, 2016, 10:07 AM   #8
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Oh the horror!

Why, o why, would someone do that?

Deface a Model 70.

I guess in the name of science I can live with it.

Interesting, but I usually don't bang the muzzle end on the ground.

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Old January 29th, 2016, 11:02 AM   #9
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That looks like some work from a local "Gunsmith" I have done business with, once. Some people should stay away from tools.
That is unexpected. I would like to see it done on several at one time to see if the results are consistent, or a fluke.

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Old January 29th, 2016, 11:58 AM   #10
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I read an article in G&A or one of the other Gunzines years ago about repairing your Crown.
It said use a Carriage Bolt in an electric drill and Valve Grinding compound and have at it.

I will just leave that thought with you.

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Old January 30th, 2016, 05:48 AM   #11
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That is a head scratcher. I'm curious if there could be a sweet spot as far as barrel length (for a given barrel) where muzzle condition doesn't matter, and if there are other lengths where it would matter quite a bit?

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Old January 30th, 2016, 07:58 AM   #12
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every one has an opinion....

I have a M1917 with a beat JA barreled muzzle that shoots the same as a friends pristine Winchester 1917 barrel.

A gunsmith told me not to pull a cleaning brush, onced exited the muzzle, back through to the chamber... but I watched a serious foreign bench rest shooter do it and shoot one hole groups.

Or different crowns are for different apps..........................

Thanks from Bamban
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Old January 30th, 2016, 01:28 PM   #13
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I was taught to clean a chamber and bore from the chamber out to the muzzle. So we don't push the residue from the burnt gun powder into the receiver and chamber. Then it's a PIA to clean.

What causes the crown to be worn and uneven in the first place? I believe we find more evidence of uneven crowns in military surplus rifles from excessive cleaning rod damage. When it's beyond recrowning they counterbore the muzzle to where the rifling is good again.

What makes the bullet inaccurate is the crown being worn into the lands and grooves this is when the hot gasses escape on one side of the bullet throwing off the accuracy. It could be 25% to 33% worn around the diameter of the bore. Again we see this problem more with surplus military rifles.
But if we cut a muzzle and it's not a square cut to the bore it increases the chances of being inaccurate. We make sure the cut is square then recrown it.

Last edited by BigBill; January 30th, 2016 at 01:50 PM.
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Old January 30th, 2016, 01:48 PM   #14
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use a bore guide and forget about it.

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Old March 26th, 2016, 01:20 PM   #15
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I have alwaysbeen told that keeping the crown of a firearm is imperative!! That article has surely given me something to think about...

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