Tears in Case necks

[snakeman]

 

Just an anecdote:... I recall using the tool you're using Long Gun and I 'trimmed' 200 Lapua .308 cases.

I was left with holes in my palms looking as if I'd just been taken down off a cross!

Change the trimmer to a design as onehole shows 

ATB

[No i deer]

51 minutes ago, onehole said:

With respect the two piece Lee trimmer is a piece of crap and will not cut nicely ,,,,at least not in the long term,,,,,,,O

They'e cut mine perfectly for nearly 20 years mesun 

[No i deer]

Looking again at the photo I think you have over chamfered inside and outside making a knife edge with the neck of the case.it only need a little chamfer in and out.the explosion in the barrel must be damaging the knife edge necks

[VarmLR]

That and the Lee trimmers imho are pretty poor.  The Lyman shown in the photo is good as are the Wilson trimmers.  If the Lee one was sharp or set up correctly it should trim properly but I have found that all Lee trimmers are a bit hit and miss and the Quick trim I found to be total garbage.  I'd be looking at buying a decent trimmer as brass is getting too expensive to think of junking after a few firings!

[No i deer]

I recently prepped my new Norma 7mm saum brass.expanded.neck turned. Resized etc etc and they are £1.50 each and I wouldn't hesitate to use the Lee case trimmer on them.ive used them on 10s of thousands of cases and think your statement on the Lee trimmers being crap is a pile of poo 

[Long Gun]

As I've said, the damage is being done before the trimming process, maybe I could do with replacing my trimmer for a nicer one but a blunt cutter isn't the issue here. 

[snakeman]

If you're happy to continue trimming that way maybe it will help you to buy the Lee cutter ball-grip; maybe it'll help you achieve a consistent technique?

However, you will notice a marked improvement in your trimming with the 'in-line' design and to do away with case-length gauge trimmer.

How have you determined the cutter is not degrading? I'd be interested to know how you've arrived at this conclusion - what tool did you use to measure the sharpness of the cutter?... .....Just because some cases trim ok does not mean the cutter is not degrading. Everything has a lifespan and a far better cutter is the carbide cutter, which the Lee case-length gauge trimmer you're using, is not.

Buy a proper trimmer and be done with problem

ATB 

 

[VarmLR]

1 hour ago, No i deer said:

I recently prepped my new Norma 7mm saum brass.expanded.neck turned. Resized etc etc and they are £1.50 each and I wouldn't hesitate to use the Lee case trimmer on them.ive used them on 10s of thousands of cases and think your statement on the Lee trimmers being crap is a pile of poo 

You can only say as you find yourself, and I found the Quick Trim especially to be utter crap, so yes, sort of related to a pile of poo  .  I'm not worried who disagrees with that, I won't lose any sleep over it.

I'm also a little confused Long Gun...how can the ragged tops of the necks be caused prior to trimming?  Unless you have a seriously messed up chamber which is scarring the brass when upon firing, it's ragging the tops, the only logical conclusion one can come to is that trimming or de-burring might be the cause?  There has to be some mechanism causing physical damage as shown and it does look a lot like what happens when too much pressure is applied with that type of trimmer resulting in flowering of the end.  You may no notice so much after de-burring but once you've fired the case and it gets a little messy, the roughness would be easier to see, so it may be a natural conclusion to say it's only noticed after firing.  It's the only obvious answer.  It's always possible that there's another reason but I think we're all struggling to see what that might be at the moment given the information and photos.

[Reloader54]

3 hours ago, No i deer said:

They'e cut mine perfectly for nearly 20 years mesun 

same here, the last decade on a hand drill and works perfect. 

[onehole]

1 hour ago, Long Gun said:

As I've said, the damage is being done before the trimming process, maybe I could do with replacing my trimmer for a nicer one but a blunt cutter isn't the issue here.

Its late doh!!,,,my last post on this,,,Long Gun,,,,,,,if you would post me some cases ,,tell me the length to which to trim  ,,,,I will also chamfer/deburr and polish as I do for my fully prepped cases using the equipment previously mentioned.You can then fire in your rifle and see if you still have a problem,,,,,,,,,,,,,,the offer is there,,,,,,,,,,,O

[No i deer]

I've still got my first Lee cutter and it still cuts as it did when it was new.i only renew the lock stud and the pilot occasionly as from being span in the cordless wears a hole in the lock stud and the tip of the pilot down 

[drum]

I used to experience similar case mouth damage to this when i was a bit heavy handed while chamfering,leaving a very sharp,thin edge which could and did look ragged after firing.

[No i deer]

Thank you drum it seems that is the answer.over chamfering 

[VarmLR]

Yes, that does seem to be the most likely cause.

[Catch-22]

I may be stupid or misunderstood the OPs comments, but he's said the cuts in the case mouth occur prior to trimming. That would also be the same before chamfering, as surely the whole point is to chamfer AFTER trimming.

So....unless the cases are coming out of a fired chamber looking like this, and the OP states it's before trimming (and chamfering) surely it's either something to do with the tumbler or sizing die?!?

OP; it might be worth you taking a photo of the case after each step of its firing, cleaning, sizing, trimming and chamfering journey. 

I agree it does look chamfer or cutter related but could possibly be its contacting & being damaged by an incorrect setup of the sizing die (if stem is too deep or contacts case mouth).

[VarmLR]

It's difficult to understand what's happening here and not at all clear I think.  My understanding is that the OP only notices the roughness after firing, and specifically after the brass is prepped.  The OP states that he trims, chamfers and deburs and post #1 states that this is when he notices the ragged neck tops:

Quote

 

Neck resize, trim case to length, deburr inside and outside edges.

Problem I'm getting is that loads of my cases seem to be left with big gouges at the tops of the necks, quite large and deep a lot of them, giving the tops of the cases a ragged finish

 

The in post #6 he says this:

Quote

The marks are present from the actual firing, not the tool however. 

...which sort of is not what he said at the start, or at least the inference is different. Post 6 suggests the firing results in ragging of case necks;  Post #1 suggests that trimming and de-burring is the culprit.

My best guess is (as others have said) that over-chamfering/heavy use of the deburring tool is to blame, so the cases form a fine edge difficult to see until firing splits the thinned brass.  It's as good a theory as any given the information.

Onehole has the best suggestion to getting to the bottom of this as after he's applied his expert hand to brass prep and the case is fired again, then perhaps the issue will be resolved (or perhaps not).  Wait and see, but money would be on the case necks being fine after firing unless this was a batch of very iffy brass, in which case I wouldn't be firing the things again.

 

[Catch-22]

On 02/04/2018 at 9:41 PM, Long Gun said:

As I've said, the damage is being done before the trimming process, maybe I could do with replacing my trimmer for a nicer one but a blunt cutter isn't the issue here. 

But it's this post which confused me, as it states the damage is done BEFORE trimming and chamfering.

 

[VarmLR]

It's a bit confusing isn't it?  No offence at all meant to the OP,  but my thoughts are that perhaps he doesn't actually know for sure himself when or what is causing the issue....too many contradictions in one thread in which he elaborates but confuses further?

[Murph]

I use these also. Although i have my trimmer motorized with a motor off a sewing machine . This has a foot control so i have 2 free hands. Very fast to operate with very consistent results.