Question on giraud tri-way trimmer concentricity

[Len5E1]

Hello Everyone,

Received my new tri-way trimmers today for 223 and 300blk and the build quality is amazing! I gave them both a whirl and noticed that both of calibers inside chamfer seem to be fairly uneven. To the point where one side has max chamfer that the tool leaves and the other side none at all. I tried a dozen cases and all results are very similar to each other. I don’t have a concentricity tool yet to test my brass but they look very even and i can’t detect anything with a caliper. Even the sample brass included with the 223 trimmer has an uneven chamfer but the 300 sample brass looked ok.

I’m just not sure what to expect but I do plan to buy a concentricity tool since it’s on my list. I just find it hard to believe that all my brass is that out of round unless both my quality resizing dies are doing a bad job with the necks. I don’t want to bother giraud with any questions until I rule things out on my end but was curious what people had to say while I wait on a concentricity tool.

EDIT: If anyone knows of a good quality concentricity tool to recommend please do!

 

[straightshooter1]

Hello Everyone,

Received my new tri-way trimmers today for 223 and 300blk and the build quality is amazing! I gave them both a whirl and noticed that both of calibers inside chamfer seem to be fairly uneven. To the point where one side has max chamfer that the tool leaves and the other side none at all. I tried a dozen cases and all results are very similar to each other. I don’t have a concentricity tool yet to test my brass but they look very even and i can’t detect anything with a caliper. Even the sample brass included with the 223 trimmer has an uneven chamfer but the 300 sample brass looked ok.

I’m just not sure what to expect but I do plan to buy a concentricity tool since it’s on my list. I just find it hard to believe that all my brass is that out of round unless both my quality resizing dies are doing a bad job with the necks. I don’t want to bother giraud with any questions until I rule things out on my end but was curious what people had to say while I wait on a concentricity tool.

To get an even chamfer, you need to give the case about a 180° turn as you trim it.

There other issue that'll show up with an uneven chamfer is due to uneven neck wall thicknesses. It'll especially show up if one is using a bushing for the neck tension where this unevenness of the neck wall thickness is moved to the inside.

 

[Len5E1]

So I tried several where I would spin the case all the way around at every degree I could and it didn't really affect anything. There does seem to be a small amount of play either in the bearing or enough space around the case where I can wiggle it just a little so holding it at hard angles made a small difference but inconsistent. I guess it's going to be very hard to determine if the tool is off without getting the proper tools to test my brass but the tool does seem like it could be a little off.

 

[straightshooter1]

So I tried several where I would spin the case all the way around at every degree I could and it didn't really affect anything. There does seem to be a small amount of play either in the bearing or enough space around the case where I can wiggle it just a little so holding it at hard angles made a small difference but inconsistent. I guess it's going to be very hard to determine if the tool is off without getting the proper tools to test my brass but the tool does seem like it could be a little off.

Yeah, it's certainly possible that the trimmer might be off a little somewhere.

Note too, that since the trimming indexes off the case's shoulder, if that shoulder axis isn't square to the case's axis, then that too can effect how even the chamfer might be. For example, if a case has a large variance in case wall thickness, the shoulder may not respond the same around the circumference of the neck, especially if annealing isn't being done.

 

[Len5E1]

Yeah, it's certainly possible that the trimmer might be off a little somewhere.

Note too, that since the trimming indexes off the case's shoulder, if that shoulder axis isn't square to the case's axis, then that too can effect how even the chamfer might be. For example, if a case has a large variance in case wall thickness, the shoulder may not respond the same around the circumference of the neck, especially if annealing isn't being done.

I was thinking something along those lines as well. It's going to take a while to get all this down but I guess that's part of the fun (also known as frustration.) I guess it's entirely possible my die is doing any number of things that will make the case be a couple degrees runout. I appreciate your input, I am in the hunt for a good quality concentricity / multi tool that will help me OCD on some of the more precision rounds. I will probably start a new thread but if you happen to have any input I was curious about the concentricity tools I've seen so far like the sinclair one. It looks like the case sits on some bearings and you spin the case while the guage does it's thing. Since you spin the case and that's what sits on the bearings, wouldn't that mean that the tool isn't just telling you the necks concentricity but will tell you if ANYTHING is out of round? I feel like any imperfection in the case walls would translate to the tool reading the neck out of round even if it's perfect? This seems strange unless I'm thinking of it wrong.

 

[straightshooter1]

I was thinking something along those lines as well. It's going to take a while to get all this down but I guess that's part of the fun (also known as frustration.) I guess it's entirely possible my die is doing any number of things that will make the case be a couple degrees runout. I appreciate your input, I am in the hunt for a good quality concentricity / multi tool that will help me OCD on some of the more precision rounds. I will probably start a new thread but if you happen to have any input I was curious about the concentricity tools I've seen so far like the sinclair one.

I went with the Sinclair one and have been quite happy with it. Though I did make a small modification to reduce the play in the arm that attached to the post. The arm had a little movement as there was some play between the arm and the post that tightening the screw wouldn't alleviate. So I shimmed the inside so that the fit around the post was much tighter and it's been good ever since.

It looks like the case sits on some bearings and you spin the case while the guage does it's thing. Since you spin the case and that's what sits on the bearings, wouldn't that mean that the tool isn't just telling you the necks concentricity but will tell you if ANYTHING is out of round?

Well, I'd say one needs to think in terms of axes. When a case is sitting on on the rear bearings at the base of the case and on the front bearings at just below the shoulder's case, those two points creates an axis that that case rotates around. The case could be the shape of a banana, yet it'll rotate around the axis the two contact points create much like the inside a chamber surface will. And yes, it will tell you things like how "out of round" it is in relation to the axis.

I prefer this method of measuring concentricity to that where the concentricity is indexed off the case base, like Hornady's Lock-N-Load Concentricity Gauge. I've found that the base of a case is often not square to the axis of the case.

I feel like any imperfection in the case walls would translate to the tool reading the neck out of round even if it's perfect? This seems strange unless I'm thinking of it wrong.

Because the pressure from firing is equal everywhere on the inside surfaces of the case where the case is pressed against the uniform chamber wall, case imperfections are actually moved towards the inside (unless you have something that can't be compressed, like too much lube (a liquid) on the outside surface). So, you're not likely to find much of any "imperfections" other than a case might tend to be the shape of a banana, even after sizing, if there's a lot of variance in the wall's thickness. Or, on ejection, the case can be dented, but sizing should take care of that.

Anyway, that's some of my thinking of the subject.

 

[MLS2GO]

This seemed like a good place to piece this info. I ordered the Giraud Power Trimmer today and asked why no Tri-Way in 6.5 Creedmoor. They replied they didn't think they could get the accuracy out of it that true match rifle shooters expected.