Too much deburring?

[Aaron47pb]

I have some trimmed brass that have a large burr on the outside of the case mouth. To remove the burr, I am having to remove quite a bit of brass. And as a result the case mouths are coming to an edge. I am new to reloading, and I am wondering - am I doing more harm than good?

Thanks

 

[HumbleEinstein]

Measure the OAL of the case and compare it to book length. That will tell you.

 

[Aaron47pb]

So as long as the OAL is not changing - or is within spec - having the case mouth come to an edge is fine?

 

[Deadshot2]

If you have a burr so large that removing it will end up putting an edge on the case mouth then I suggest that you replace the cutter on your trimmer. Burrs like that are a result of the metal being "rolled over the edge" rather than being cut off.

Burrs are a normal part of the cutting process with brass but can be minimized by using very sharp cutters and high speeds (like with the Dillon Rapid Trim). What remains should be thin enough that you really aren't tapering the case mouth at all.

 

[Aaron47pb]

If you have a burr so large that removing it will end up putting an edge on the case mouth then I suggest that you replace the cutter on your trimmer. Burrs like that are a result of the metal being "rolled over the edge" rather than being cut off.

Burrs are a normal part of the cutting process with brass but can be minimized by using very sharp cutters and high speeds (like with the Dillon Rapid Trim). What remains should be thin enough that you really aren't tapering the case mouth at all.

Got it. I used a brass processing service, so I am stuck with the large burrs on this batch.

Will the cases coming to an edge noticeably affect consistency/results?

Thanks

 

[Deadshot2]

Got it. I used a brass processing service, so I am stuck with the large burrs on this batch.

Will the cases coming to an edge noticeably affect consistency/results?

Thanks

I doubt that there will be any effect on accuracy. The thin edge will eventually disappear as you fire/trim over time. What you might consider, if the burr is on the outside,remove as much of this burr first with a pocket knife. Just line the blade up with the case and cut it as square as you can before using a de-burring tool. Another way would be to use a neck turning tool if you have one. Just set it so it skim's the end of the neck but doesn't cut the outside of the neck. If the burr is on the inside of the neck, (often there is some on each so it looks huge when just looking at it), use the edge of a straight bladed screw driver to knock the burr down to square with the ID of the case then apply whatever chamfer you want to finish with.


Looking forward you've learned the most important lesson in life. If you want something done properly you often have to do it yourself. Rather than sending cases off to a "case prep company" invest in some basic equipment so you can do it yourself. With apologies to those companies that do a great job, all to often there are those who are interested in how fast they can do the job rather than how well they can do it. Sounds like you found one of the latter.

 

[myownman]

I still use the RCBS chamfer tool. Sometimes I have to tilt the tool at a angel to knock off the burr, Not so much that the inside stem contacts the inside of the neck tho.

 

[Bill Larson]

I HAVE AN rcbs CASE CONDITIONER station...with 5 stations to deburr,chamfer lube and clean cases in one location small space...

 

[No1]

Is your deburr tool dull? a dull edge will roll the burr. it should be sharp and cut the burr off.

 

[Deadshot2]

Is your deburr tool dull? a dull edge will roll the burr. it should be sharp and cut the burr off.

Note in the OP's post that he "Used a case processing company". This is what they gave him back and he's trying to solve it.

 

[No1]

Let be more thorough with my reply.

After case trimming a burr is often left on the inside as well as the outside of the case mouth. There are many tools available to remedy this problem. Most common tool used by handloaders is the Cartridge Case Chamfer Tool. One of the limitations of the tool that you should be aware of is the 45* cutting angle. In order for the burr to be removed effectively it must cut into the squared off end of the case mouth thereby removing some extra material that otherwise does not need to be removed. Use a light touch to prevent removing extra material. A sharp edge on the Chamfer Tool is a big plus here. If it is dull it will roll the burr down even more. Why I use the Sinclair carbide tool, it stays forever sharp. A sharp edge on the case trimmer is also a big plus here as it will help prevent haveing a large burr in the first place and leaving a bunch of extra material that you have to remove with the chamfer tool.
This is a good place to insert RULE #1 of Chamfer Tools -- NEVER ROTATE THE TOOL OPPOSITE THE DIRECTION OF CUT. (This rule applies to the Case Trimmer also as well as chamber reamers and other precision cutting instruments. Why is RULE #1 so important? Because it dulls the cutting edge and causes ill results in the finished work.
The cartridge neck wall thickness is fairly thin. So yes, if you remove too much material you will shorten the case and it will leave a gasket cutter edge. Don't worry about it too much if you have gone a bit under "minimum trim length", a couple firings will stretch it back out to spec.

 

[Aaron47pb]

Thanks for the replies.

I've set up my RCBS trim pro with the 3-way cutter to remove the burr on both the inside and outside of the mouth and its working pretty well without actually trimming the cases any further.