.223 Inconsistent Trim Length - I'm stumped.

[MikeMcCasland]

Gents,

Need some ideas/help. I'm using a Giraud trimmer to trim all my .223 brass, and I've used it successfully for quite some time. That said, I've changed a few things in my reloading process, and as of late my trim consistency has gone down hill; I would normally attribute this to a shoulder bump consistency problem, but I can't seem to detect a problem with headspace comparator.

Brass Details:
Lapua .223 Brass
~4-7x fired with heavy charges of Varget behind a 90gr VLD.

(Relevant) Reloading Process:
Deprime
Wet Tumble
AMP anneal
Resize w/ Redding Type S bushing die & Redding comp shell holders (setup for .003 bump w/ a 'camover' fit).
Mandrel expand back up .001.
Dry tumble lube off
Giraud trim

Here's the screwy thing, I'm getting consistent shoulder bump indications on my brass using a Hornady comparator. They're all within .001 of each other on the setback (showing 1.458 - 1.459), however when I run them through the Giraud, I'm getting wildly inconsistent trim lengths. The trim lengths are varying ~.010.

Typically with a trimmer that indexes off the shoulder this would indicate a shoulder bump problem, however they're all showing very closely on the comparator.

Any ideas? I've re-setup the trimmer/dies/shell holders repeatedly, and can't seem to figure it out.

 

[memilanuk]

Usually when I trim on the Giraud, if I feel one or more cases suddenly feel like there is little or no trimming taking place, I grab the calipers and start checking. Typically they are a bit long, like you describe. The problem usually seems to be something in the case holder - some bit of debris, tumbling media, maybe a shaving from a previous case, etc.

I keep a soft bristle brush on a short handle (e.g. .338 bore brush on a Sinclair plastic handle, for a .308 Winchester) with a couple large cotton patches and a squirt bottle of M-Pro 7 cleaner - the same setup I use for cleaning the gunk out of reloading dies - nearby when I'm trimming on the Giraud. Wet the patch, stick it in and wipe out the case holder, give it a few seconds to dry, and the next case trim length should be back to 'normal'. The only tricky part is that the spring-loaded case holder in a Giraud trimmer tends to want to spin with the brush/patch; you have to apply a bit of pressure with a finger tip to hold it in place so you get an effective wipe of the inside of the case holder.

HTH,

Monte

 

[Texas10]

Is the cutter sharp? A dull cutter will make an inconsistent cut. I use a trimmer that indexes off the shoulder. WFT trimmer in a drill press. Takes about 5 seconds each.

 

[shotdown]

Are you seeing a bulge just above the neck/shoulder junction of the brass that the Redding bushing die is not sizing at all?

 

[MikeMcCasland]

This was driving me crazy though dinner tonight, so I figured I'd troubleshoot further. The carbide expander mandrel is pulling the shoulder forward (I think), but ahead of the datum line the comparator uses.

I took 5 cases and ran them back up into my bushing die; the comparator changed, but only .0005 smaller, and I had to really spin them to get that change. These aren't Starrett or Mitutoyo calipers, so definitely within the margin of error.

That said, I ran them in the Giraud immediately afterwards and they're now consistent, but trimming way shorter than what I wanted. I set it up for 1.763" trim length, but it trimmed all of them at 1.750 on the dot.

I'm thinking the annealing softened up the brass enough to where the mandrel can pull it forward? That's the best I can come up with, and even that is hard to believe, as I'm lubing the inside of the case mouth and using a carbide mandrel.

I guess I'll neck turn and change bushings to do the same thing.

 

[MikeMcCasland]

Actually never mind. Did 5 more and there's still variance.

 

[MikeMcCasland]

Are you seeing a bulge just above the neck/shoulder junction of the brass that the Redding bushing die is not sizing at all?

Not much of one, but I'm in the process of setting up an expanderless FL die to bump like my bushing die.

We'll see if that's it.

 

[Dusty Stevens]

Run them thru the trimmer a few times taking them all the way out and rotating them. If your shoulder bump is the same its gotta be in the trimmer. Something is loose

 

[Twoboxer]

If you take multiple COL measurements on the same case with the caliper in different positions (small rotations of the case in between measurements) . . . are the measurements pretty much the same?

If not, you may not be holding the cases square in the trimmer, and so trimming at an angle.

 

[MikeMcCasland]

Ok...just did the following.

Lubed ~10 cases, ran them into a Type-S die and did not expand back up. Cases were reading 1.4595. Resetup the giraud case holder and put a different hornady lock ring on it. Cases weren't trimming consistently.

Relubed those cases, ran them back up into a Redding FL .223 die without an expander and set them up to bump 1.4585 (basically just push it back .001 from the above test). Expanded them back up using a mandrel. Cases weren't trimming consistently.

Relubed those cases up, and setup the FL die using a standard RCBS shell holder, and set that to bump at 1.457 (like above, pushing it back another .001), and it's still screwed not doing it.

Checked the giraud cutter, it's still very tightly secured by the allen screw, and the cutter body is firmly in place via the wrenches.

I'm ordering some Mitutoyo's off Amazon right now. None of this makes any sense.

 

[JFrank]

Do you have a case gauge?

 

[MikeMcCasland]

Do you have a case gauge?

Unfortunately not. Always just used the comparator.

Unless you count my cutting case gauge, the giraud.

 

[shotdown]

Not much of one, but I'm in the process of setting up an expanderless FL die to bump like my bushing die.

We'll see if that's it.

I ask because I have some Remington brass that bulged a bit in that area and gave me inconsistent numbers. Used my Dillon FLS die that reaches the shoulder and numbers were back on. The Redding bushing die doesn’t size all the way down to the junction and has caused my cases to stick in the Giraud case holder at times.

 

[MikeMcCasland]

I ask because I have some Remington brass that bulged a bit in that area and gave me inconsistent numbers. Used my Dillon FLS die that reaches the shoulder and numbers were back on. The Redding bushing die doesn’t size all the way down to the junction and has caused my cases to stick in the Giraud case holder at times.

It was a good suggestion, and I certainly agree with the logic. I ran them up into a standard (non-bushing) Redding FL die to size that portion of the neck, but no joy.

I'm in the process of ruining cases while trying to perfectly align a new cutting blade now.

 

[Ned Ludd]

I have always used Redding Type S Match dies for my .223 Rem F-TR loads with 90 VLDs. I always remove the expander ball. With Lapua brass (unturned necks; no-turn neck, PTG .223 Rem ISSF 0.169" fb chamber), a 0.248" bushing has always given me the ~.002" neck tension (interference fit) I was after.

A while back, I an idea that seemed great at the time, why not use a slightly smaller bushing to size the necks down below my target diameter for ~.002" neck tension, then use a 0.222" mandrel to open them up as the final step. I figured any unevenness in neck wall thickness would be pushed to the outside, rather than the inside as a bushing will do, and, if anything, they might even be a bit straighter with the mandrel.

As it turns out, that approached worked just fine, with the exception of a couple little problems. First and foremost, it was not a detectable improvement over simply using the 0.248" bushing, and it also required an extra step. Second, when opening necks up with a mandrel, spring-back works in the opposite direction from a bushing die setup. So I was ending up with something more like 2.50 to 2.75 thousandths neck tension instead of .002". It simply wasn't worth the extra effort, and I went back to my original method.

I have used my Giraud trimmer with cases prepped by both of these approaches and not noticed any inconsistency such as you have described in case length. My target length is 1.750", and the cases are all within half to one one thousandth of that. So I can't really offer any insight on why you are experiencing such case length variance with your Giraud. However, I would offer the observation from my experience in messing around with mandrels that if something isn't broken, don't fix it. A simple one-step bushing die with the expander ball removed can give excellent results, and will likely minimize the opportunity for other things to occur that create issues such as you are having now. Simpler is often better.

The only other suggestion I can make is to measure both case OAL and base-to-shoulder lengths from a set of cases before and after the trimming process, if you haven't already done this (it sounds like you might have). At least then you would have a more specific idea of where on the case the length variance was showing up (i.e. neck versus case base-to-shoulder region), which might give you a better idea of what was causing the issue. Because the Giraud indexes off the shoulder, slight variance in case base-to-shoulder length shouldn't affect neck length, but it might impact overall length. As has been mentioned, anything such as brass chips in the case holder could definitely create variance in neck length. Finally, the blade on the Giraud is V-shaped, so it can cut both inside and outside neck chamfers when adjusted properly. However, if the bottom of the "V" isn't adjusted such that it is actually trimming the very end of the neck between the inside and outside chamfers, I can imagine that might also contribute to variance in case OAL. In other words, the Giraud can chamfer the inside/outside of the case neck without actually touching the region in-between, which is where case OAL is measured. Finally, is the inside/outside chamfer (bevel) uniform, both in terms of height, and uniformity all the way around the case mouth, as far as you can visibly detect on the cases that end up at different lengths? If the bevel isn't uniform, that might also give you some clue as to what is going on.

 

[MikeMcCasland]

Greg,

Thanks for the reply. You've described everything I'm doing to a T; literally everything the exact same (chamber, dies, bushing, brass etc.) .

I've also measured OAL, as well as base to shoulder before and after trimming, and I still see variance in trim length.

I rotated the triangular cutter to use a new blade, and I've got it centered up correctly (I love this trimmer, but man I hate trying to center a new blade on it. ).

Having slept and had some time to reflect, you're correct. If I'm not seeing any variance in case head to datum measurement, then my variation *should* be from datum to case mouth. That said, I would have thought running this brass into a traditional FL die would have fixed it (i.e. fully resized the neck/shoulder junction). Hell, I even expanded one up to 6.5mm, and then FL sized it back down, and re-opened it with a .222 mandrel.

My only other thought is that these brass have quite a few firings on them (relatively speaking, for a varget/90gr setup). Some of the case heads are slightly expanded a bit (sticky in RCBS shell holders, but fine in Reddings) and I've pulled multiple pieces out due to signs of incipient case head separation etc..

I'm wondering if there's some section of the body that's a little 'proud' for the giraud case holder. That or I've got some variation ahead of the datum that I don't have a good way of measuring.

It's driving me absolutely crazy though. I've never seen an inconsistent trim length problem on a giraud that wasn't directly related to shoulder bump.

 

[JFrank]

Unfortunately not. Always just used the comparator.

Unless you count my cutting case gauge, the giraud.

From the teachings of Mr.Guffey
A Comparator has eased edging, perhaps not as accurate as you believe.
Wilson case gage is a datum based tool that is highly recommendable and very revealing.
Brunos sells a standard gage for around $25
I have attached the overview and instructions for user below.
J

 

[243winxb]

Still the trim problem. http://forum.accurateshooter.com/threads/giraud-help-likely-a-shoulder-bump-issue.3955713/

Time to chuck that trimmer.

 

[MikeMcCasland]

Still the trim problem. http://forum.accurateshooter.com/threads/giraud-help-likely-a-shoulder-bump-issue.3955713/

Time to chuck that trimmer.

I've grown my knowledge/capability significantly since that post. It's not the same problem.

 

[243winxb]

Could the bushing sized neck cause the problem? Edit. Oops seen u used a std fl die.

The instructions say

The inner sleeve
of the case holder is contoured
with a chambering reamer of the
appropriate caliber to hold the
case.

Have Giraud replace the inner sleeve? Defective?