Indicated Crown?

03 January 2004, 00:59

Smokin

Indicated Crown?

What is an indicated crown?

03 January 2004, 04:18

Ricochet

Maybe it refers to that Australian fellow they say is the true heir to the British throne?

03 January 2004, 05:55

triggerguard1

Quote:

What is an indicated crown?

Well first, it's a poor term by whomever told you. Second, what it should be referred to is a properly cut crown that had been indicated in before cutting.

Basically, the barrel was dialed in on an indicator in a 4 jaw chuck on a lathe. After it was running true to the boreline in the chuck jaws, it had the crown of the barrel remachined.

The reason that I referred to it as poor terminology was due to the fact that I can "indicate in" crowns all day long, but until they are cut after being indicated in, it's an exercise in futility. Not to mention, I'd probably be the only guy in the world doing such foolishness.

03 January 2004, 07:05

Smokin

Thanks for the help. If I am following you correctly, then the process of centering the barrel correctly in the lathe is reffered to as "indicating in" the barrel. So the meaning of an indicated crown has nothing to do with crown type or style, but rather the process used to crown the barrel? The reason I ask is I am thinking my barrel could benefit from being recowned due to past cleaning abuses(I am trying to repent as I become more informed). I have looked at various web sites for gunsmith work and see the phrase "indicated crown" commonly used along with a price, or see it listed as a feature on various custom rifles. When inspecting my crown with a magnifying glass, it appears the land edges are not all perfectly uniform. Am I correct in concluding it should improve performnce if they were? The rifle shoots pretty fair...inside 1 MOA, but in times past has done .5 MOA, so I wouldn't mind seeing if that would restore it to former performance.

03 January 2004, 16:42

Smokin

Thanks, I appreciate it...

03 January 2004, 17:58

Robgunbuilder

A new crown almost never hurts although it's usually a good idea to cut off the last 1/2 to 1 inch of barrel and then recrown. Muzzels tend to get belled and eroded due to the plasma torch like effect of the burning gases suddenly having their pressure extremely rapidly reduced. That's why you see those burn patterns on the muzzel in a radial pattern. On guns that burn alot of powder like .50 BMG,s your accuracy will fall off after about 500 rds. I'd expect it would take even less for a badly overbore cartridge like a 30-378 fo example. I put a new crown on my target .50 BMG every 500 rds.
As for indicating a new crown,the right way is to first pull the barrel, chuck the muzzel in a 4 jaw, and the chamber end in a spider on the backside of the headstock, put a tight fitting plug guage in the bore at the muzzel end and a precision fitted brass rod in the chamber end so it also is centered in the bore( for a few inches)and indicate both ends to dead Nuts zero,remove the muzzel plug guage and then cut a new crown. I've tried 11 degree crowns and my results are no better than a std target crown. Check and remove burs and your done.! There may be better ways of doing this, but this works for me.-Rob

03 January 2004, 20:20

7x57mm

I have a 7x57mm which shoots three 162 grain Hornady SSTs into sub-half minute of angle at 100 yards. It is a CZ 550 American with the original factory crown (not what I would consider a good crown either). Would this rifle benefit from a re-crown job even though it shoots so darn well? Thanks for any reply. Tom Purdom

04 January 2004, 02:23

Terry Blauwkamp

Quote:

I have a 7x57mm which shoots three 162 grain Hornady SSTs into sub-half minute of angle at 100 yards. It is a CZ 550 American with the original factory crown (not what I would consider a good crown either). Would this rifle benefit from a re-crown job even though it shoots so darn well? Thanks for any reply. Tom Purdom

Tom:

Don't mess with it until it starts shooting larger groups.

If it's not broke, don't try and fix it.

04 January 2004, 07:10

7x57mm

Thank you Terry. That is about what I thought, but wanted to check anyway. Have a tolerable day if you so desire! Tom Purdom