A friend noted significant increase in accuracy when he chamfered some brass in his .260AI, and didn't chamber in others.

I'm doing a batch now, deburring the outside and camphering the inside.  I always do this, but the campher on the inside will bevel that inner edge and keep the bullets from shaving off jacketing during seating.  I'm using a 20* (or is it 22*) VLD campher tool now.

Chris

You should chamfer all your brass after trimming to help with seating, some that use carbide cutters on their trimmers and get a smooth cuts don't bother chamfering(I still do) but it's recommended to chamfer all brass every trimming.

I guess it depends upon how many other things you're planning on doing to your cases to squeeze the most accuracy out of your rounds as you can.  I trim my cases on a Dillon trimmer and call it good as my goal is 1MOA level accuracy in my ARs (I'm not a BR type shooter) and in my tests with my rifle and my level of performance, trimming didn't make a difference so I stopped doing it.  





However, if you're going all out on accuracy and taking the time to really prep your cases, then I would say you need to also chamfer.  BTW, if you're going all out, you really need to do much more case prep than the average shooter is willing to do.  An article in 6mmBR.com lists 11 different case prep processes to ensure maximum accuracy. Chamfering is only one.
Reason:
When we turn the necks, the blade will bite into the shoulder the same distance
for each case.








Step 2


































 
 

I lightly chamfer and debur all of my processed rifle brass after trimming...to me it's more to debur the inside of the case mouth.

not quite the same, but when i started using my giarud case trimmer i noticed a big increase in accuracy.  before that i only trimmed when they were out of spec. with the giarud i trim every time. i suspected that the caused the crimp to be consistent.

Sir, in my humble opinion there are quite a few different process that can be applied to bottleneck cartridge cases that will together improve the consistancy and precision of an assembled cartridge, case neck champfering or deburring included.  While I respect CoSteve's opinion regarding case preparation I will say that some of the steps he has listed from the linked article are actually done in tandem with other steps and in the instance of neck trimming is a process generally not considered adviseable for cartridges intended to be used in gas operated semi-auto rifles.

From the very first time I ever trimmed a cartridge case I've always also deburred the case mouths.  Initially I did that because that's what the directions said but later because I realized some equivalence to belling the case neck of a pistol cartridge to facilitate the seating of the bullet.  As I progessed through a variety of trimmers I continued to deburr case mouths as I realized that some of the trimmer cutter blades left a somewhat acute edge on the inside of the trimmed case mouth and to some degree shaved the bearing edge of the bullet during seating.  FWIW, when I used a Dillon trimmer I continued to deburr case necks as on occasion I had to pull a seated bullet for one reason or another and was able to see the effects on the bullet bearing of not deburring the trimmed case necks.  Also, as already mentioned I also trim every case after resizing.  I no longer bother to measure them, I trim them all to 1.758".  Now that I use a Giraud trimmer, the trimmer does it all, ie:  trim, and deburr inside and out.

All in all I can't honestly say that I've noticed any difference in accuracy of my reloaded cartridges, mostly because I've always deburred trimmed cases as part of my normal case preparation processes.  HTH, 7zero1.

The OP didn't state he was reloading for an AR, just a .223.  In addition, HERE is the link to 6mmBR's post and you can plainly see that they are the ones who specified that there are 11 separate steps, I just copied their titles and short statement.



In addition, I specifically stated that I'm not looking for the nth degree of accuracy in my ammo; 1MOA is sufficient.  At that level I've seen no difference between just the Dillon trimmer followed by tumbling and then reloading using BT 55grn, 62grn, and 68grn bullets vs chamfering the cases after trimming.



YMMV!   It's up to each of us to decided what we find acceptable.

I use a Dillon trimmer and trim to 1.750. The Dillon does leave a slight burr, but after trimming I run the cases through a full length sizing die to deprime. I find that the full length die irons out the bit of a burr that the Dillon leaves.

Since I've been processing brass this way, I've quit chamfering and notice no difference in accuracy.

Is the die that the Dillon trimmer uses a SB die or a regular FL sizing die, I ask because I'm thinking about getting one but I'm pretty picky about sizing my brass and prefer to only size my brass with my Redding Type "S" FL bushing die and wounder what the opinions are of the Dillon die on the trimmer.

Is it worth resizing the case with the Redding die after trimming or has the Dillon die already sized the case so much that the advantage of the Redding die is already lost from the first sizing?

I don't have a definitive answer. I've read that the Dillon is a small base die, but when sizing with my standard RCBS full length die, I feel resistance, making me think the Dillon might be larger then small base.

If you are concerned about oversizing with the Dillon, I would think you could set the trimmer die a bit high so it doesn't 100% size the case when it trims.

Sir, I can't say if the Dillon trim die is small base or not.  When I used a Dillon trimmer I did as My Sleepercaprice suggests and didn't use the Dillon die to resize my brass, only trim.  You do this by not screwing the die down far enough to resize the brass but far enough for the cutter shaft to trim the case.  The Dillon trim die does resize the case neck more than I wanted.  I would resize and deprime my brass with a Redding die and then trim with the Dillon.  I found that if I modified the ID of the neck portion of the trim die it still worked just as well without reducing the case neck more than already done by the Redding die.  It worked well for me but I still believe deburring was needed.  I used to do all the deburring by hand after trimming, now it's all done in one step.  HTH, 7zero1.

What is your case length after resizing trimmed brass?  I would think that would leave your brass length all over the board.

I agree, I'd recommend not doing it that way myself as you're reworking the brass again and pulling the case neck longer again.  



As far as any burs left after trimming, I tumble my lubed cases about 15 minutes to remove the lube and any burs I can see are gone after the tumbling.  With respect to the sharp edges after trimming.  I use BT 55grn, 62grn, and 68grn bullets and have had zero incidents of scratching or gouging the bullets.  (I've pulled a few test bullets of each type to look for scratches and there weren't any.)  For the outside edge, I have the crimp die set to just touch the corner to round it off a bit so there's no need for me to chamfer the outside, I let the die do it for me.



Maybe I'm not as picky as others but I can't see any damage to the bullets from not chamfering the inside, I don't have any problems placing the bullets on the cases, and my crimp die smooths the outside edge in the final station so they don't snag on anything.  So, based upon my observations and the fact that my testing shows no accuracy difference at distances of 300yds between my trimmed cases and the test ones I inside chamfered, I abandoned the process as unnecessary for my desired accuracy.  



However, YMMV.



 

There was a thread a few months ago that addressed sizing after trimming with the Dillon RT-1200. It had something to do with a few people felt the trim die for the RT-1200 left the case mouth too small, or too much neck tension, or something like that. I think when they resized, they really were using the expander ball portion of the die.

COSteve, I think you posted in that thread as well. I gathered from the thread that some people size after they trim with the RT-1200 and some people don't.

jonblack

Case length doesn't change substantially. The RCBS die barely drags the cases after they have been through the Dillon. Most of what the die contacts is the necks and they are still well lubed. If I was a benchrest shooter I might not do my prep this way, but for my purposes it is plenty precise. If my case length was to vary by a couple thousanths, I certainly am not going to worry about it.

This method has worked fine for ammo loaded for praire dog shooting at over 400 yards and works well with my progressive press.  

Hope this helps: I use the Dillon .223 sizing die for anything (good brass) I'm going to shoot in my AR type rifles because it is the highest recommended die by JP Enterprises for semi-auto shooting, the sizing is right on and never a proper battery fit problem.

And, I use Redding Type S Bushing dies (both full length sizing and neck sizing only) for Lapua brass that I feed into my .223 bolt guns. All sized brass gets a whiz through my Giraud trimmer set at 1.752". Some cases get a buzz on and are well chamfered; others hardly get a tingle because it did not need trimming, and chances are it did not need chamferring.

My AR treated brass and bolt gun treated brass never see the inside of the others chamber.