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Forum Index > Rifles general discussion > Trouble shooting.

Trouble shooting.

20 Dec 2017
@ 03:54 pm (GMT)

Andrew Murray

Hi all. Just a question on case prep.

I am getting different lengths on the cases after prep. My trimmer rod is 51.19mm long but even after just trimming my case length was 50.93mm. Is there a reason this might be the case? Is it the shell holder?

Also from 20 cases my finished lengths after trim and chamfer were between 50.8mm and 50.95mm. Quite a range. Most were 50.87-50.91mm.

Am I being to rough on the chamfer or inconsistent with the shell holder in the drill when I trim? Would love some help all.

Thanks heaps.


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22 Dec 2017
@ 06:52 am (GMT)

Thomas Kitchen

Re: Trouble shooting.
the lee trimmers are great specially if your only loading few calibers, ill have to do more in depth checking over the holidays after see Andrews results, i normally just trim with one chamfer and load never really bothered checking because that's half the genius around them, they are pretty foolproof.

i discovered that the 6.5 rem mag is exactly same length as 6.5-284 so i just use a 6.5-284 one for that.
i use slightly shortened 300 win mag one for my 308 norma.

a lot of people don't understand some of lee designs as they are so far from what they are use to.
i once done a video about the lee collet dies to explain them to a mate i put the internals in a G clamp so you can see how they work when you tighten the clamp.

23 Dec 2017
@ 01:03 am (GMT)

Paul Leverman

Re: Trouble shooting.
It's 4 a.m. here. I've only had one cup of coffee. So it's probably my muddled mind trying to conceive this, so be patient with the following question.

What's the big deal? Does 0.00113xxx" (or whatever the number was) really matter? Does it make that much difference? Why all the fuss over such a miniscule amount? There is probably more difference in the neck thickness or the wall thickness to affect accuracy than the one thou in length.

Could someone please explain this to me. If it is this critical, then I will have to go through thousands of cases to resize.
23 Dec 2017
@ 09:00 am (GMT)

Nathan Foster

Re: Trouble shooting.
You are correct Paul, quite correct, there is no big deal.

The micro changes in OAL are as you say, no more of an effect than changes in wall thickness or temper. We have used the Lee system for many years for precision ammo for ourselves. Steph was going to post that for a number of years, she also made (winning) comp ammo for clients but decided that this thread has already gone on long enough and that she cannot force anyone to understand how or why the system works.

As an example of normal practice, lets say I load 60 rounds for a basic client day tutorial. All cases are trimmed to minimum before hand. The client uses my rifle for say 20 rounds, then switches to another rifle. I have another client arriving next week so I load the 20 cases again. I check the case lengths for safety, but I don't trim. The same thing happens again, and again. Eventually my 60 rounds are all at different lengths. But I will not trim until I am within a C-hair of maximum as I do not have time to p around with this and the rifle is shooting one ragged hole with a low ES when testing it between client visits.

One thing to watch for Andrew, is over analysis during down time when you cannot get to the range. I have seen this effect folk at all levels, from newbies to bench resters. To be sure, if you want to take things to the next level, then you may want to look at flash hole uniforming, neck turning and annealing. However it is more than likely that your rig will shoot very well with basic case prep.

If the case has a burr in the flash hole big enough to effect the lee pin, it is an indication that the flash hole needs uniforming. It is not an indication that you need to use a different trimming system. The flash hole burr needs to be removed. Visual inspection of the flash hole is the first basic step. Trouble aligning the Lee mandrel can be another clue indicating very large burrs. If the burrs are not addressed, they may cause ES and accuracy issues.

Again, do not overthink this. Talking about accuracy and achieving accuracy are two different things. Take note of Marty's comments. Marty will always down play his skills so I will say it- he is a highly qualified and well respected engineer. The way we use our tools is of great importance. We cannot use a cutting lube to aid high speed case cutting as this results in contaminants. So either run your drill at low speed to avoid glazing or cut by hand. The tool is no less accurate than a high end neck turn tool.

This should have been a very straight forwards discussion. Too much time behind computers and not enough time at the range.
23 Dec 2017
@ 09:08 am (GMT)

Andrew Murray

Re: Trouble shooting.
Hi Paul,

I think you (and a lot) have misunderstood, which probably means I have not explained myself well. My point in posting the hand drawn chart was to highlight the difference between my work using the case holder with and without a drill. The hand drawn chart is the results without the drill. They are much closer, the the point of insignificance, than with the drill. The results with the drill had a range of 0.15mm, without resulted in 0.03mm, with a margin of error of 0.02mm. The point was just to compare not suggest it as a standard.

Apologies for any confusion.
23 Dec 2017
@ 06:03 pm (GMT)

Paul Leverman

Re: Trouble shooting.
No need for apologies, Andrew. It was 4 a.m. Nobody in their right mind (hence, me) is up at that hour trying to figure out gun stuff.

24 Dec 2017
@ 02:56 am (GMT)

Trace Jacoby

Re: Trouble shooting.
Hi Andrew, I know I am a little late to the party, but I thought I’d throw this in the discussion as another possibility. I’m not sure if it would apply to the unit that you are using, as I have not seen a Lee, but it may help someone else reading this.

My trimmer is an RCBS, emphasis on the BS. The first time I tried to resize cases, my results were all over the place (and I am still pretty new to it). I thought for sure it was user error. I slowed down and did each step slowly to see what I could be doing wrong, that’s when I noticed a little play on one end of the trimmer. It turned out that there were some screws that held the thing together that were not tight, allowing excessive play when trimming.

Now, every time I get a tool, I check how it is put together and check all screws and such to see that it was assembled properly. Unfortunately, that is not the first time that sort of thing has happened to me. It always pays to check!

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