Inconsistent trim lengths

[Chernobyl]

Hand loading some 3x fired Hornady brass and after trimming with Wilson ultimate trimmer with micrometer, I am getting trim lengths varying as much as .005. The micrometer trimmer is set at fixed position so that is not cause. I’m applying same amount of pressure to handle so eliminated that possibility. Mitutoyo digital has been triple checked so that’s not the issue. This has never happened with 1x or even 2x fireformed brass. I am knew to handloading so wondering if anyone else has had this problem and knows a fix?

I’m probably wrong but have narrowed it down to two possibilities.

1) case heads are not square due to firing and ejecting from rpr 6.5

2) work hardened brass is causing inconsistent trims.

Could either be the cause? Thanks in advance

 

[BOB LEE SWAGGER]

The tap that you use to seat the brass in the case holder has to be exact as well.

 

[DngBat7]

Try what bob lee said, And also, turn the hand crank longer than you think you should, Even if you feel no resistance. I found after I did that my trims were uniform down to .0005

 

[JFrank]

All of the above

 

[JFrank]

I finally had to trim the other day after 10x resized
Wilson cut them perfectly

 

[nmkid]

Some cases require a different case holder for fired and unfired cases. However, if that was the problem you would be aware of that right away. As Bob Lee Swagger noted the cases need to be tapped in the exact same amount. That is one of the reasons I got rid of my Wilson trimmer. Never could figure out how to tap every case the same amount.

 

[AJC]

The bite of the cutter may give you that difference as well imo. Soft brass grabs and cuts easy and hard brass resists the cutter more and will be the longer cases. This happens in machining and is why a primary and cleanup pass are made.

 

[Chernobyl]

Thanks guys for all the advice

 

[Chernobyl]

So I’m currently doing load developement with this brass. What variation in length ( ie .001, .002, .003 etc ) should I allow before culling and using as sighters

 

[Short Bus]

I would bed that 100% of your variation ic coming from a dull cutter. Not that I have had the same problem. You could theoretically be getting some slippage of the case in the case holder but you would probably notice that. The fit of the case inside of the holder doesn't really have a bearing on case length since it just serves to support the case

 

[JFrank]

So I’m currently doing load developement with this brass. What variation in length ( ie .001, .002, .003 etc ) should I allow before culling and using as sighters

Nah”
They are what they are
Just keep shootin your fine.

 

[BenPerfected]

My current 6 Dasher brass necks have never been trimmed. Most brass is 3X to 8X fired and the necks are .0100. The brass is annealed every 3-4 X fired. I question that .003-.005 variance in neck length can be measured on paper.
Comments please,
Ben

 

[jackson1]

BenPerfected, has asked a good question regarding OAL lengths of cases (effects of tolerances). I am very happy with my Wilson trimmer as opposed to others and have no trouble holding +/- 0.001". As an old retired guy, I take my time and having spent my life working in a machine shop, find all the handloading processes a labor of love. I spend many happy hours in my gun/reloading shop and striving for constant improvement. I also understand that work and family can place a number of time constraints on your time.

 

[Mad_Charlie]

Are you sizing before trimming? Are there any little burrs or dings on the rims?

 

[Webster]

Hand loading some 3x fired Hornady brass and after trimming with Wilson ultimate trimmer with micrometer, I am getting trim lengths varying as much as .005. The micrometer trimmer is set at fixed position so that is not cause. I’m applying same amount of pressure to handle so eliminated that possibility. Mitutoyo digital has been triple checked so that’s not the issue. This has never happened with 1x or even 2x fireformed brass. I am knew to handloading so wondering if anyone else has had this problem and knows a fix?

I’m probably wrong but have narrowed it down to two possibilities.

1) case heads are not square due to firing and ejecting from rpr 6.5

2) work hardened brass is causing inconsistent trims.

Could either be the cause? Thanks in advance

There should be a mechanical stop to limit the depth of cut. Work hardening has nothing to do with it. As someone else mentioned it must be how the case head is inserted and held. Is 0.005" variation important? Is there a way to check head squareness? Carefully insert the head in the holder cut then turn the case 180 degrees and see if it wants to cut more brass off.

 

[JMayo]

The holder can be anywhere it holds the case butt against the back so it doesn't spin or jump around ......
The thickness of the rim can vary.
old primer in? The cup edges are .005 in a fired primer.
.005 is almost unmeasurable. Squeeze just a tad more and it'll disappear.

 

[Chernobyl]

So I cleaned everything real good and made sure to maintain the same very light pressure as I turned the hand crank slowly. Variations are almost non existent now. Must have been rushing the night before or taking out my frustration lol. Thanks for all the advice guys.

 

[jimmymac]

Glad you got it solved, but...

To clear things up. The case does not have to be seated in the exact same position inside the case holder. As said above, as long as it is tight enough so the case doesn't spin you should be getting consistent results since the cutter is indexing off the case head. The case holder is just along for the ride.

 

[Sniper338]

Your doing something wrong... buy the fired case holders only... forget about the ones for new brass... sales gimmick.. the amount of tap doesnt matter to snug the case in the holder. I didnt tap them in, and did tap in thousands on mine... always repeatable.

The biggest issue I found was the arm that secured the shell holder. Dont use it. Hold the shell holder and case snug against the micrometer case head stop with your left hand, trim with the tight hand.

I never had 1 case not come out exact with this trimming set up.

 

[JMayo]

The stop won't let the cutter go in any more with pressure.....
I park that case in the thing and crank like I'm making electricity !
My left hand fingers get cramps from holding the shell holder so tight. At# 150 im wishing I'd got that screw on holder thing.....lol !
I do vacuum the tiny brass pieces up as needed so not to cause a problem.