Why ream inside case necks

[PiratePast40]

I'm starting to reload .223 and am doing batch prep of cases. For trimming, I'm using a Lyman E-zee Trim with the bits mounted in a battery operated drill. There is good reason to deburr the outside of the cases, but not understanding why the need to chamfer, ream, or otherwise remove any additional material from inside the case neck. I'm concerned that it may be an issue of thinning and weakening the case.

Is there really an issue with burrs inside the case mouth after trimming?

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[Capn Jack]

I shoot lead, so I always chamfer the inside of my case necks to prevent any sharp edges from , "Shaving" the bullets.

Chamfering the the inside of cases would also help starting a flat based jacketed bullet when seating the bullet.

 

[Caveman Jim]

It's more about placing a bullet on the case, an inside chamfer allows flat point bullets to be guided/centered in the neck.
It's been a task that's been done for decades, go with it my man, you will not mess up anything.

 

[red442joe]

Chamfer yes, ream no.

Joe

 

[Mikej]

I'm starting to reload .223 and am doing batch prep of cases. For trimming, I'm using a Lyman E-zee Trim with the bits mounted in a battery operated drill. There is good reason to deburr the outside of the cases, but not understanding why the need to chamfer, ream, or otherwise remove any additional material from inside the case neck. I'm concerned that it may be an issue of thinning and weakening the case.

Is there really an issue with burrs inside the case mouth after trimming?

In my relatively new to shouldered rounds experience, there are the same burrs on the inside as the outside after trimming. I don't think I want to do a boat tail bullet even through that. And a flat base bullet in that case is asking for trouble.
That's my opinion.

 

[bcp]

Deburring, chamfering, and reaming are different things.

Deburr to remove trimming burrs to improve bullet seating consistency.

Chamfer to make bullets start easier, especially lead bullets.

Ream after many reloadings to reduce increased neck thickness which can raise pressure. Benchrest shooters may neck ream or outside turn to make case walls equal thickness.

Bruce

 

[PiratePast40]

Chamfer yes, ream no.

Joe

I'm getting the impression that the reamer is the tool and the chamfer is the end result.

 

[Member 34319]

Depends on what you are looking to do.

If you just want it to go bang, it's not needed.

If you want .25" groups or better at 100 yards, it's best not to mangle up your bullet while seating it into the brass because you didn't remove all the rough crap that forms from firing/resizing/cleaning etc.

 

[PiratePast40]

Deburring, chamfering, and reaming are different things.

Deburr to remove trimming burrs to improve bullet seating consistency.

Chamfer to make bullets start easier, especially lead bullets.

Ream after many reloadings to reduce increased neck thickness which can raise pressure. Benchrest shooters may neck ream or outside turn to make case walls equal thickness.

Bruce

Hmmm, more to consider, Thanks for getting more into the details. Makes me look closer on what is being done and why.

It sounds like chamfering is a good idea for all cases, not just the ones that have been trimmed.

 

[Nwcid]

A 3-way trim die prevents all of the "extra" steps. They are worth the price if you have very many to do.

 

[red442joe]

A 3-way trim die prevents all of the "extra" steps. They are worth the price if you have very many to do.

Ha! This!

Joe

 

[red442joe]

I'm getting the impression that the reamer is the tool and the chamfer is the end result.

Not really....chamfer tool to chamfer; heavy deburr, with a deburr tool, on the inside can qualify as chamfer.
bcp's post was really good.

Joe

 

[red442joe]

A 3-way trim die prevents all of the "extra" steps. They are worth the price if you have very many to do.

After trimming 600 ish 223's on a Forster tool, I made my own powered inside/outside deburr-chamfer tool!
Case prep sucks...

Joe

 

[Local Loader]

Yeah, not a fan of chamfering 223/5.56 case. Had to many issues with the necks getting a slight crimp when being powder charged on an AP press. I just do a light reaming like you would copper pipe and and use some lube on the butt of the bullet. RCBS has a bullet lube that's wax based so it won't hurt the powder. Bonus is it seems to create a wax seal to prevent moisture from getting in, at least with mine anyway.

 

[PiratePast40]

Deburring, chamfering, and reaming are different things.

Deburr to remove trimming burrs to improve bullet seating consistency.

Chamfer to make bullets start easier, especially lead bullets.

Ream after many reloadings to reduce increased neck thickness which can raise pressure. Benchrest shooters may neck ream or outside turn to make case walls equal thickness.

Bruce

I was under the impression that the reamer on the Lyman case prep multi tool deburrs and also chamfers the inside of case neck. Is that incorrect?

 

[Local Loader]

I was under the impression that the reamer on the Lyman case prep multi tool deburrs and also chamfers the inside of case neck. Is that incorrect?

View attachment 1317084

Not with a single bit but yes it does do both tasks.

 

[DizzyJ]

Deburr/chamfer the inside of the mouth for sure. It's a small task that will help to eliminate many issues down the road. Reaming is a different animal altogether and it's not needed for the majority of case work one needs to do.

 

[po18guy]

Try a VLD (Very Low Drag) inside neck chamfer tool. Cuts less of the neck at a very steep angle and aids in bullet placement and seating, especially of flat-based bullets.
Inside neck reaming (to a specific diameter) is for bench rest and other competitive shooting.

 

[ageingstudent]

Deburring, chamfering, and reaming are different things.

Deburr to remove trimming burrs to improve bullet seating consistency.

Chamfer to make bullets start easier, especially lead bullets.

Ream after many reloadings to reduce increased neck thickness which can raise pressure. Benchrest shooters may neck ream or outside turn to make case walls equal thickness.

Bruce

This. +1

 

[ageingstudent]

Try a VLD (Very Low Drag) inside neck chamfer tool. Cuts less of the neck at a very steep angle and aids in bullet placement and seating, especially of flat-based bullets.
Inside neck reaming (to a specific diameter) is for bench rest and other competitive shooting.
View attachment 1317211

I have one of these and I love it. It's got the outside debur and primer tools in it also. Very handy. Works quite well. Came from the factory super Sharp so you don't have to push very hard. It's one of the few Lyman tools I have that I actually like.