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Discussion Starter · #1 ·
I've never crowned a barrel but I just ordered a crown lapping tool and some 600 grit compound to do it while my rifle is apart (I have some 220 and 320 already).

Exactly how important is doing this? I've read how to do it and it seems too simple to do. Just chuck up the tool in a hand drill, get some compound on it (read to start with 320 then move to 600) and oscillate the drill as you work it into the crown. Seems like easy maintenance to keep the rifle shooting straight (can't say it's that easy to keep myself shooting straight). I may start doing this every 1000 rounds or so depending on how easy/hard it is to get my brake on/off/aligned.

So why don't I ever hear more about doing this? Not needed? Not known? Not easy?
 

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I have never done a re crown before. but this much I will say. You will be hard pressed very very hard pressed to keep a Hand Drill Square to the Barrel.
 

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I know sigma05 bought a recrowning tool, you may want to shoot him a pm or email(let me know if you need his address). From his description it was not very hard. I dontt hink he used a drill, pretty sure he did it by hand. I remember reading one of Art Luppino's (cactus comet) threads, where he mention the crown area is one of the most overlooked areas that needs cleaning due to carbon build up. He went on to say that this is part of his cleaning regiment but dont rememeber the frequency. Probably once a season. you may want to consider cleaning it more often(each season) I would be interested to know whatt he wear rate is. Do you plan on keeping records and making TE measurements?
 

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Discussion Starter · #4 ·
...you may want to consider cleaning it more often(each season) I would be interested to know whatt he wear rate is. Do you plan on keeping records and making TE measurements?
No, just want to get the most bang for the buck out of the Krieger. Seems an easy to overlook item considering this is the first time I'm going to do something with one and this is my third Krieger. I guess rather than being scared of touching the crown I'd rather be able to maintain it properly. The lapping bit is only $9, if it gives me even a small amount of sustained accuracy it's worth it. I may look into getting stand alone TE and MW gauges. The BAD T-1 was cool and all but just too much going on with it. Something to be said for simplicity...
 

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Discussion Starter · #5 ·
I have never done a re crown before. but this much I will say. You will be hard pressed very very hard pressed to keep a Hand Drill Square to the Barrel.
You aren't supposed to. You oscillate the drill so you don't wear on the same place repeatedly and the crown lapping tool doesn't get a weird wear pattern. It's a ball shaped piece of brass with a shaft for the drill.
 

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I get good crowns on .30 cal muzzles with a 1/2" white ball stone, the Dremel tool at mid-speed, and Colgate white toothpaste lapping compound. The ball won't let you mess it up, runs $2.50 to $3.00. Stick a mop in with a little Kroil on it before crowning, screw on a pistol cleaning handle afterwards and pull out the mop.
 

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Could you post a Picture or link to this Tool as now my curiosity is Peaked
 

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Thank You I apologize I was Thinking of a Different Crown Tool
and please Keep us Posted as to your Results
 

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This used to be accomplished by the use of a brass round head screw. This has the added benefit of the screw slot holding some lapping compound to feed the proccess. This was the common method prior to cheap import tools and the internet. The hardware store on the corner has a wide variety without the wait.

Historically the purpose for lapping the muzzle was to remove any ding or dents from a muzzle crown. With the flash hider installed, it would be difficult to damage the crown on a M1A. I can not recall a crown sustaining damage soley from firing but it may happen. That said, properly done it should cause no harm and may true up a factory deffective crown. I have had significant benefit on bolt guns as this area is definately disrespected on typical hunting rifles being thrown in the pickup, barrel on the floor and bouncing around. Besides a good cleaning, recrowning a barrel can take that deer rifle that just "quit shooting" back to out of the box accuracy or better.

I hope this helps,

Rick
 

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Josh I picked up my MW guage from LRB, it was the one Ted Brown sells which I think he had made at PTG. So when I purchased the TE guage I bought it from the same place PTG. They are listed on the brownells website but you know me I bought it direct. It's is the one that works on both 30-06 and 308. When your ready to get them let me know I'll give you the friend price, double. Lol only kidding. Nice additions to the tool box.
 

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Discussion Starter · #12 · (Edited)
Here's my thinking... skewed as it may be... This barrel was shipped from Krieger (WI) to 82nd (NY), 82nd (NY) shipped it to me (CA), I played with it a couple months, I shipped it back to 82nd (NY) and he massaged it onto my receiver, 82nd (NY) shipped it back to me (CA)... all this without a muzzle device attached and in the hands of UPS. Then I put the rifle together, alignment gauge in and out a few times, MW gauge in and out playing with the BAD T-1, now it's back apart and in my closet with a fresh coat of Alumahyde II on it after numerous trips between the house and garage. LOTS of opportunities for something to nick the crown so I figure why not get the little tool and clean up the crown? That way when I finally put my shiny new SureFire brake on it I know the crown is good to go.
 

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When you think about it that rifle has some serious air miles too bad you didn't get sky miles with it. If it makes you happy hav at it my friend. Let me know when I'm changing the brand new barrel again! Lol
 

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I tried that tool on my Springfield standard barrel. There are many marks on the crown that just got plated with chrome in finishing. The tool ended up doing nothing because the chrome is so hard, though. Hopefully you'll have better luck with your CM/SS barrel.
 

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Discussion Starter · #15 ·
I tried that tool on my Springfield standard barrel. There are many marks on the crown that just got plated with chrome in finishing. The tool ended up doing nothing because the chrome is so hard, though. Hopefully you'll have better luck with your CM/SS barrel.
I'd be scared if a brass ball and lapping compound got through the chrome they use in the bore.

Should be fine on my SS barrel.
 

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The whole point of having a 'good' crown is so that when the bullet leaves the muzzle it doesn't get 'deflected' somehow.
That means the crown has to be symmetrical all the way around, and without any burrs.

If the crown is even a few .001 off-center the gas pressure would be slightly different around the bullet when it left the muzzle.
Do you think it is possible to be that accurate with a hand tool?
The crown might 'look' nice & smooth, but is it aligned properly?

If visual inspection of the muzzle doesn't show any defects, then I wouldn't start chewing on it with handtools.

If it DOES need to be recrowned, then find a riflesmith who has the tools to do a good job.

And, I'd do some test firing first... the factory crown is probably fine.

Jay Kosta
Endwell NY USA
 

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Crowing the M1A muzzle..

There are a number of ways to accomplish this, some are better than others. There are also a number of reasons for crowning or re-crowing the M1A.. Most of us do it to ensure accuracy, if there is any in the first place, or in hopes the accuracy improves. or stays as is...

The best method is on a Lathe with a proper ground crowning tool. Most barrels have this machined crown when we get them.. What the interested M1A owners are concerned about is keeping the Crown in excellent condition. How often to service the Crown is an open question, I rework mine at least every 2000 rounds.

The round headed brass screw with compound is the method most often used and a good one, but that should be a follow up effort after re-cutting a fresh Crown with a quality hand tool or on a Lathe.

The purpose of Crowning is, or one of them is, to make an attempt to have all the Lands, four and six, all end at the same time and same place in the bore.. If one Lands is longer then the others, it will influence the bullet as the last thing to touch as it exits the muzzle, that is not always to your best interest. Sort of like throwing Slider in Baseball...

I would not suggest Crowning a Chrome lined GI Barrel ever... Art
 

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I've recrowend a SKS barrel using a hand drill and a borazon or aka CBN ball grinding tool. It's a boron nitride dimamond composite. It can easily digest chrome, however the barrel I did wasn't. You use a ball grinding tool because the sphere will "square" itself to the bore as you oscillate the drill. This method is found in gunsmithing literature, so I'm guessing it holds true. That's my 2 pennies.
 

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Interesting thread. Thanks Art for chimming in. Since I have all chrome lined barrels I guess I can avoid this headache! GI1
 

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On M1A, I use a lathe and a TPU 322 carbide tool with zero rake.
I make a cut across the muzzle. at 90 degrees
and with the flash hider there is no need to cup it with a ball to protect the crown.
I re-cut them every 1,500 to 2,000 rounds when the accuracy drops off.
If you use the Brownells re-crown tool you need to make a stop colar for it or you will get bad chatter marks around the crown.
Ed
 
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