Chamfering vs flaring

[condor bravo]

I question why more reloaders, when preparing cases, choose to chamfer rather than use a flaring tool to bell case mouths. If just removing inside burrs, fine, but going much farther with the tool (chamfering) can result in cutting a knife edge ridge around the case mouth rather than keeping the mouth square. A chamfer or flare is usually not even needed whem seating jacketed bullets so why remove material from the case mouth. If loading lead bullets the small chamfer flare is not sufficient and bullet shaving or neck collapsing will occur. If belling must be done, and for lead rifle bullets it must be, use a proper flaring tool. This would be the Lyman (or I think RCBS has one) M Expander die. This will flare the neck as needed without removing any metal. They are priced around twenty dollars and one bullet diameter size fits all. Meaning that the same die is good, for instance, for all .30 calibers. A taper crimp should then be used to remove the flare upon seating the bullets.

Some no doubt consider simply removing inside case neck burrs as chamfering but it is not. The definition of chamfer is to bevel and the reason given for beveling or chamfering case mouths is to facilitate bullet seating. This is hardly necessary with jacketed bullets so why remove brass from the case mouth when not necessary? However beveling must be done with lead bullets and this best accomplished with the Lyman M die by putting a flare in the case neck.

So I guess my main point here is why put a bevel edge on the case mouth by removing metal from the case mouth when it is of no benefit or not even needed? Also I think that some are misusing the term chamfering (bevelling) when they just mean inside case mouth deburring. But if you do need to bevel (flare) rifle case mouths, get the proper tool, the M die.

 

[Bart B.]

The main reason they chamfer case mouths instead of belling is it only has to be done once until the case is too long and needs trimming back a few thousandths.

Belling has to be done in a separate die operation every time the case is fired. Too much of it gets straightened out by neck expansion against the chamber neck.

If a case mouth's chamfered with a traditional tool then the sharp inside edge deburred and smoothed off by an Easy Out screw extractor of the right size, then bore brushed, that inside edge will be very round and not scrape jacket metal off bullets unbalancing them. And it lasts until the case needs trimming.

 

[condor bravo]

Right, I acknowledge the above but does that mean that it, chamfering, really needs to be done when using jacketed bullets. I maintain that it does not and is just deforming the rifle cases. I reload over 35 rifle caibers and have never flared a case but with two exceptions with jacketed bullets. They are the straight walled 45-70s and .458 Win mags. These of course require a flare. And many of my magnum loads are with lead bullets that require a flare (using an M die) to keep from collapsing case necks. I guess my main point here is that chamfering, in the true sence of the word, is not necessary with jacketed bullets (with maybe rare exceptions).

 

[Bart B.]

If the case sizing dies are of good quality and correctly dimensioned, no rifle case needs a flared case mouth for jacketed bullets. Normal deburring is good enough. If jacketed bullets deform deburred and chamferred cases when they're seated. there's a dimensional issue that needs to be resolved; case, die or bullet.

 

[AllenJ]

I guess my main point here is that chamfering, in the true sence of the word, is not necessary with jacketed bullets (with maybe rare exceptions).

They call it camfering but in reality you are only supposed to remove any burrs that cause undo stress or damage to the bullet while seating it. I used to be one of those people until I realized a single twist with medium pressure is all that is required.

 

[mikld]

Any metal I handle usually has all sharp edges removed. I deburr the case mouths of my rifle brass, not for ease of bullet seating, but from many years experience as a machinist/mechanic; habit. So, yes true chamfering is not needed (a non-issue as far as I'm concerned).

FWIW; several years ago I was sizing some .38 Special brass (no chamfered mouths) and was going great when I removed my finger from the case a bit too slow and cut a nice chunk outta my left index finger. Nice clean cut So, an edge, not necessarily chamfered/sharp can hurt...

 

[higgite]

My brass for jacketed AR fodder gets trimmed with a Giraud trimmer that deburrs inside and out. It leaves a little bit of a chamfer. I never considered it a big deal one way or the other. ymmv

 

[mehavey]

If I trim, I chamfer. (the Giraud does both simultaneously, but most hand tools do not.)
If no trim is req'd, no chamfering is required (normally)

(minimal) Belling is normally for flat/plain-base/cast bullets

 

[WIL TERRY]

CHAMFERRING is meant to break the 90* inner edge on the case mouth, Not sharpen it.
Belling is strickly for and only ever needed when using non-jacketed lead bullets.

 

[44 AMP]

This is hardly necessary with jacketed bullets so why remove brass from the case mouth when not necessary?

Sometimes it is necessary. I have found that chamfering cases (NOT after trimming, I always do it after trimming) is usually not needed, but sometimes, it is.

I was suffering an unacceptably high number of neck collapses in .22 Hornet cases, no matter how carefully I seated the (jacketed) bullets. Chamfering the case mouths solved the problem.

 

[Unclenick]

Condor Bravo,

If you buy a box of Lapua cases, you find them factory chamfered. Lapua does this for their commercial loading, too. There are two reasons: one is to help the bullet base self-center over the middle of the neck opening, and the other it to avoid scraping bullets (not an uncommon thing to find on commercial ammo), though they do make the chamfer fairly smooth. As Bart mentioned, you need to burnish the case mouth with something to completely avoid it. I use to run a freshly chamfered case over a carbide expander a couple of times to accomplish that, but Bart's E-Z Out method is better and I've been using it since he first posted the idea.

The M-die expander is a little bit of a different animal. The small step it forms near the mouth of the neck helps bullets start into the neck straighter so the finished cartridge tends to have less runout on a concentricity gauge, provided you were careful not to bend the necks in the first place. It can allow a standard seating die to perform about as well as one of the benchrest/competition type seating dies do with just chamfered cases. The downside is more neck working. You can expect to anneal more often to prevent neck splits that start at the case mouth. You also, especially for a self-loader, want to set the crimp shoulder in the seating die down enough to iron the step out, which can be ignored with standard loading of a chamfered case, and which also adds to more working of the case mouth brass.

 

[T. O'Heir]

Chamfering is done to bottle necked rifle cases. Like mehavey says, it's only done after trimming. New cases require it too. If you're putting a sharp edge on you're chamfering too much.
Flaring is done to handgun cases regardless of trimming or the bullet material.