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View Full Version : Crowning for cheap....... Yugo SKS


westphoenix
September 25, 2006, 03:40 PM
I have a Yugo SKS I am modifing.
We don't need to get into the legal issues of this.
I am just looking for help on muzzle crowning.
My first idea was to remove the barrel and turn it on a lathe.
But there is a lot of pins that are pretty suborn and I decided to do it by hand or with a hand drill attachment.
I would like to keep the tool cost under $50 if possible.

I have already cut the barrel.
I'm going to do some filing to get the muzzle straight.
The 11 degree counter bore cut seems popular.
Which I am considering.
But what other options do I have?
Where to buy the tooling (remember I want to keep it cheap, I will probably only use the tool once)?
Is it best to do this by hand or with a drill?

Would I be better off (cost wise) taking it to a local gunsmith to have the crown cut?
What is the estimated cost of this?

Thanks,

EDIT:
I also heard of using a brass screw, thoughts? expierences?

sleeping dog
September 25, 2006, 04:26 PM
I did it to one rifle, cut the barrel from 26" to 22". I used a grinder to get it as square as I could. Then a ball-shaped stone, 1/2" dia, to grind an indentation at the muzzle. Then a brass screw in a drill with valve-grinding compound to polish it.

It shoots great. A "real" muzzle tool would probably have done a nicer job and done it faster, but this worked.

We don't need to get into the legal issues of this.

If you think you have legal issues, don't even think about taking it to a gunsmith. He doesn't need the aggravation. If he thinks he has to choose between his license and your ass, then adios ass.

Regards.

westphoenix
September 25, 2006, 04:48 PM
No I know what I am doing is legal, I just didn't want the conversation to turn into what I need to do to the Yugo to be legal. I want to keep it on the muzzle crown issue.

Unclenick
September 25, 2006, 07:51 PM
I prefer lapping a crown. See my first reply post in this thread (http://www.thefiringline.com/forums/showthread.php?p=1937797) for a description. Not a free lunch in terms of bother, but not a big expense, either. The main thing is the muzzle needs to start out truly squared with respect to the bore for it to work accurately, and that means doing more than just eyeballing it.

Since the Brownells tool that squares a muzzle is outside your budget, you can take a 1/4" brass rod that goes all the way down the barrel and buy a bronze shoulder bushing that slips over it, shoulder against the muzzle, and use that and Magic Marker or match smoke or high spot blue to see where the shoulder rubs? This tells you where to scrape or file. If the rod is all the way through the barrel, its error angle will be pretty small, but you can use tape to bring the fit still closer. The object is to get the bushing shoulder to touch evenly all around the muzzle for as far out as the edge of the crown is to go.

Don’t get too worked up about muzzle crown angle. Harold Vaughn tried a bunch of different ones, and as long as they were symmetrical about the bore axis, it didn’t make any difference to accuracy what angle they were. As an aerodynamicist, he suspects the 11 degree number comes from a mistaken notion that because an 11 degree angle is the greatest departure a bullet’s boattail can make without incurring more than laminar flow drag against its sides, that this angle would somehow be helpful to bullet exit ballistics. Just pick something that recesses far enough so the edge of the bore is protected from minor bumps and dings. That’s the purpose of a crown, anyway. Otherwise, the square cut would be king.

Nick

T. O'Heir
September 25, 2006, 10:15 PM
Getting a flat surface with a file takes a great deal of skill. Proper crowning tools run $600 from Brownell's. Take it to a smithy.

dfaugh
September 26, 2006, 03:03 PM
Getting a flat surface with a file takes a great deal of skill. Proper crowning tools run $600 from Brownell's. Take it to a smithy.

SAY WHAT? I bought my crowning tools from Brownells. The initial cost (I bought a "squaring cutter" and an 11 degree crowning cutter), then you just buy the pilots for the appropraite caliber. As I recall, it cost me about $120 for the initial setup (the 2 main tools, and one pilot). But, additional pilots (I now have half a dozen) only cost a few dollars. So, if you even THINK you might want to do another gun in the future its worth it to get the right tools.

I've seen all sorts of "home grown" methods for doing re-crowning, and after many years of metalworking (some work, some play) I find it REAL dubious that anyone can get REALLY good results, without the proper tools. Might work, more or less OK, but not gonna give the best possible accuracy.

westphoenix
September 26, 2006, 05:05 PM
This is my first time doing this and need to do it for cheap.

Let me make sure I understand this:
I should be using a squaring tool, this tool will have a pilot that is inserted into the barrel and the cutter will cut the muzzle square with the bore.
Then I should using a crowning tool, to cut the crown. The crowning tool will also have a pilot that is inserted into the barrel to center the crown.

I may need to do this to another SKS in a few months to a year.
If I decided to spend a few extra bucks now (keep it under $100) what tools should I buy? Remember this will probably be used once or twice.

I wish I could rent these tools.

8milimeter
September 27, 2006, 12:53 PM
I have used this technique on several rifles with great results. If you take your time you can make it look like a factory job.

http://www272.pair.com/stevewag/muzzle/mz.html

westphoenix
September 28, 2006, 12:34 PM
8mili thats actually what I planned to try.
Ill let you guys know how it comes out.