I was talking with a friend the other day and we were having the discussion of whether or not a "match" barrel needs a crown if it's going to wear a muzzle device of some kind for its entire life? Or is a crown not necessary in this situation? Does having a crown or not having a crown affect accuracy if the barrel is wearing a muzzle device of some kind its entire life?
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Gunsmithing Barrel crown under a muzzle brake?
- Thread starter cdeiglmeier
- Start date
I would say yes as the very last thing to have any bearing on the bullet is the rifling at the crown. Like the tips of a quarterbacks fingers releasing a football, for lack of a better analogy... I believe having a nice square crown would be more important than the style that is cut beneath the brake.
So imo, having a properly cut, "square to the bore" crown would be important with or without a brake.
So imo, having a properly cut, "square to the bore" crown would be important with or without a brake.
I use mostly recessed crowns just to try to give the crown itself a little protection. I have cut them on my barrels that don't have them. I don't have a lathe yet so I'm doing it the hard way via T-Handle facing cutter and crown cutter to recess and square the crown to the bore via a brass pilot.
All my builds are basically field rifles for lack of a better term... I don't shoot matches much and mostly hunt. So my rifles are always being knocked and banged around and the muzzle gets knocked around fairly often. So i go with recessed to help protect it a little.
All my builds are basically field rifles for lack of a better term... I don't shoot matches much and mostly hunt. So my rifles are always being knocked and banged around and the muzzle gets knocked around fairly often. So i go with recessed to help protect it a little.
Most crowns are designed to provide protection if the muzzle is banged around...
If there's always going to be a muzzle device attached, type of crown- including flat- is just fine.
As long as it's square and concentric to the bore and the gases exit evenly as the bullet leaves the bore all's good.
If there's always going to be a muzzle device attached, type of crown- including flat- is just fine.
As long as it's square and concentric to the bore and the gases exit evenly as the bullet leaves the bore all's good.
I go back and forth on this. At first glance, it seems important.. buuut I've cut down barrels lots of times with a band saw, then just for shits and giggles before I thread the muzzle in the lathe, will screw it all back together, clean up the muzzle with a chamfer/debur tool and shoot it. Every time I've done it they still shot well under MOA. I haven't got OCD enough about it to do a proper test but I was totally expecting 1.5-6 MOA and it didn't happen.
There’s been a few who did that and were surprised at the results.
Here’s a picture of carbon buildup on my crown under my can from a while back. Didn’t affect accuracy that I could notice.
There’s been a few barrel length to speed tests published that they test accuracy a bit as well.
It’s out there.
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Whether it was cut off in a band saw or finely crafted in one of many shapes, every barrel has a crown. That’s simply the nomenclature for the face of the muzzle.
Here's one they cut with a chop saw as they went:
rifleshooter.com
On a side note, I've had good luck using the 308 velocities listed in this^^^ article when I didn't have a chrony handy...
308 Winchester / 7.62x51mm NATO: Barrel Length versus Velocity (28″ to 16.5″)
308 Winchester / 7.62x51mm NATO: Barrel Length versus Velocity (28″ to 16.5″) Introduction Released by Winchester in 1952 (and adopted by NATO in 1954 as the 7.62x51mm NATO), the 308 Wi…
rifleshooter.com
On a side note, I've had good luck using the 308 velocities listed in this^^^ article when I didn't have a chrony handy...
Sorry should have clarified. We were referring to an actual designed crown like a 11 degree target crown or the other fancy types compared to a straight flat crown. I'm no gunsmith nor do I claim to be, that's why I figured asking in this specific gunsmithing forum, what the masses that have much greater experience than me know. I don't have the funds to test such a thing either; hence the question, because maybe someone has or a smith who's cut lots and lots of barrels has seen a difference.
Some people get pretty uptight about the crown shape they want. As others have said above, it doesn’t matter at all.
I agree, but it was what I had when I took that picture for a response to something on here a few months ago. I’ve had to use a chisel to chunk it off on other occasions.
That stuff can be like iron!
I’m currently running an experiment.
I’ll post it if it doesn’t turn out to be a shit pile.
While it's probably true that it doesn't have much effect, I don't think anyone wants to be running a rough, jagged crown that aids in excess carbon buildup. Like the pics above, it's bad enough with a good crown when running any muzzle device/can. If you spend all the time it takes to make everything else on the barrel square and concentric, then the crown would be no different. Whether it makes a big difference or not, I would rather have it square and concentric than not.
I've never really delved into it much, but 11° seems to be what most so-called "target" crowns are machined to. If I remember correctly, I've read that the 11° number has something to do with the gas venting after the bullet breaks the seal with the rifling. Anyone know why everyone seemed to land on 11°?
What I meant was, regardless of what crown I cut, 90, 11, flat, recessed, protruding, it absolutely doesn’t matter. I’m not advocating cutoff barrel is good or good enough. The 11 degree came out of the Houston BR tests where a group of guys shot In a warehouse, and tested all sorts of things. Bullets, barrel lengths, crowns etc. I seem to recall that 11 was no better than any number of other angles they tested, that’s just the one they picked. It’s been a long time since I read it though. The vast majority of my builds have 90 degree crowns and usually some sort of muzzle device, or a recessed 90.
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The crown of the crusted barrel I posted above was an 11 degree cut barrel crown. Carbon doesn’t care.
I got ya, I had read something about it years ago but couldn't remember. But that sounds right, from what I can recall. I cut all 90° recessed crowns on my barrels. Except for the my threaded barrels which all have a standard 90° crown.
That's funny it was just a random number they decided to with though. But not that surprising because I've never seen any real, hard evidence that it makes any difference. So that makes perfect sense.
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