Sinclair Concentricity Gauge

[TRexF16]

Where can one find the trutool? Or I do you just get an aluminum half inch thick angle drill holes to fit the various case necks!

I bought mine from the company (web link shown stamped on the tool in the pics I posted) but can't find it online now, so I have no idea where they went.
If you make your own, don't use 1/2" angle, use 3/8 instead, which is what the TruTool uses. 5/16 might work too. If the plate is too thick, it might impinge on the bullet itself and the idea is just to fix the neck to case body misalignment, not to try to tilt the bullet in the neck.
Should be easy to make if you have the needed drill bits and/or reamers to get the holes just a couple thou over the OD of the loaded case necks.

Cheers,
Rex

 

[SeboCreek]

Can the member that did the case holder, etc on 3 D printer make these out of sturdy enough plastic? I looked to and they are no longer in business.

 

[asd9055]

a drill gauge might work

 

[Alibiiv]

Well, yes, because most of the time it's the case neck to case body relationship that's the culprit. Often it's not the bullet so much that has the runout as the case. I find that if a case is straight, and I have my dies adjusted well with a seating stem that matches the profile of my bullet (which you can custom make for yourself with some epoxy), then the bullet will be straight too, and vice versa. IF the cases are very straight but the loaded round has bullet runout, I would be exploring fixes to the seating process. So, back to your question:

If you look at how a concentricity gauge works when you're measuring case neck runout (no bullet loaded yet), it is basically measuring the misalignment of the case neck to the case body. Let's say that's .003 "TIR." You seat your bullet, use the gauge to check the runout now and it's .004, which isn't too bad since you only induced a thou in seating the bullet, and that might just be because you're moving the measurement point further from the case. As you roll the cartridge around in the gauge, note the point where the needle on your dial indicator (or the digits for yuppie digital guys - LOL) is at its lowest value. Slide the cartridge into the appropriate hole with the same side "up" that was "up" when your TIR readout was at its least. With the heel of your hand braced against the benchtop, use your fingers to put a slight upward pressure on the case body. Then put it back on the gauge and check the new runout. It's subtle, but you will very quickly get the feel for it. it is pretty easy to get a cartridge that has some runout, no matter how much, down to the .001 range. I could swear I have seen a video of this being done but a search is not succeeding now. There are a couple threads on the 24 hour campfire about it, and the tool is also sometimes called Tru angle.

Hope this helps,
Rex

Okay thanks, I get it. Essentially one has to develop a "feel" for the correction. And your moving the neck of the brass to make the correction.

 

[Mikecr]

TRexF16, I'm suggesting that straightening bullet pointing with a any tool, or hole in a wall, is not going to address the case length behind it that is still not straight. That runout still shows on a v-block, and the only way to straighten that banana is to fire it in your best die (your chamber).

Understand that the runout matter is only to relieve detriment from excess in the entire case length. This, to prevent chambered tension.
It is NOT about concentric bullet pointing. You'll gain nothing there, as ammo rests loose in it's chamber, pointing wherever.
The best we can do is make straight ammo, which is then concentric as well(not that it matters).

 

[TRexF16]

TRexF16, I'm suggesting that straightening bullet pointing with a any tool, or hole in a wall, is not going to address the case length behind it that is still not straight. That runout still shows on a v-block, and the only way to straighten that banana is to fire it in your best die (your chamber).

Understand that the runout matter is only to relieve detriment from excess in the entire case length. This, to prevent chambered tension.
It is NOT about concentric bullet pointing. You'll gain nothing there, as ammo rests loose in it's chamber, pointing wherever.
The best we can do is make straight ammo, which is then concentric as well(not that it matters).

Thanks Mikecr, I think I see what it is you are concerned with. Do I understand you right that you believe bullet runout is caused by the entire case having a gentle curve to it - the "banana" you referenced? If that were the case (no pun intended) I could understand your argument versus the way I am describing fixing runout in loaded rounds. But I have never encountered that opinion regarding the source of case runout. My experience and everything I have gathered from others over the decades is that cases with runout get that way during the sizing process, and the culprit is the sizing of the neck, usually the expansion step after the neck has been sized down already. In normal full length dies this happens when the case is entirely unsupported as it is pulled over the expanded ball on the way out of the die. This is easy to test by checking straightness after a trip through the sizing die with the expander ball removed and compare it to a "normally" FL sized case. The former is almost always straighter. It's also the reason traditional neck sizing dies sometimes produce more runout than FL dies - the case body is unsupported both when sized down and expanded back up. Collet dies and bushing dies avoid these risks by the nature of how they work, and tend to produce straighter cases. Many of us FL size with no expander, then run the case necks over an expanded mandrel so they get expanded on the upstroke, and avoid much runout that way.

I'll reiterate I am not discussing straightening a bullet. The bullet never touches the tool and the bullet's position in the case neck is unaltered. You simply secure the neck in the precision hole, and nudge the case body in the right direction to eliminate the misalignment of the case body to the case neck. Then you roll it in the v-block (concentricity gauge, in this case) to confirm the correction, and repeat until it meets your needs. (I always got for .001 or better since it's easy to do so). There is no way to tell, using the concentricity gauge, the difference between a case that came out of the sizing process straight and a case that was a little off but got straightened the way I am describing. I have not encountered cases with the body having a curve to it but I have not spent a lot of time looking for it either.

I'm not trying to argue, but rather to understand your point since it doesn't match my experience or knowledge.
- If the reason a case (and the subsequent loaded cartridge that was made from it) has runout is that the case neck got misaligned with the case body during sizing, and I eliminate that misalignment, why isn't that a legitimate fix?
- Is it your belief that it's not case neck misalignment that is the primary cause of measured case neck runout, but rather a gentle banana curve that runs the entire length of the case?

Looking forward to better understanding your point.

Cheers,
Rex

 

[asd9055]

@TRexF16 in my case I have RCBS dies and I am not in a position to buy others. Would you remove the decapping/expander, use a universal decapper and then use the RCBS NECK EXPANDER PLUG after FL size?

 

[TRexF16]

@TRexF16 in my case I have RCBS dies and I am not in a position to buy others. Would you remove the decapping/expander, use a universal decapper and then use the RCBS NECK EXPANDER PLUG after FL size?

You don't want the RCBS NECK EXPANDER plug for bottleneck rifle cartridges - it's for straight-walled pistol cases.

RCBS dies, by their design, actually give you some good options that you would not have with, for instance, Redding (and I really like Redding so that's not a slam on them).

I like using a Lee universal decapper, so if you have one (or can spring for the $16.50 best price on Amazon) use it first, before FL resizing/shoulder bumping with the RCBS decapping rod removed. If you have another set of RCBS dies for a smaller caliber, you can just put that decapping rod in your FL die and go ahead and size/bump and deprime all in one step, but leave the necks unexpanded.
From here reinstall the original, correct for caliber, expander ball. Use its adjusting screw to retract it almost all the way up into the case (since you don't need it to deprime). That, BTW, is the thing Redding die design doesn't allow - they won't retract the expander ball as far up into the die body. The idea is that you will now run your FL sized (but not yet neck-expanded) case back up into the die and expand the neck on the up-stroke. The right height for the expander ball is such that you can push the neck completely over the expander ball without the case mouth entering the portion of the die that sizes it down. Only run the case as far into the die as required to run it over the expander ball, then bring it back out. Your cases may turn out straighter if you leave the decapping rod lock nut loose so the expander ball "floats", and centers itself in the case neck (this, BTW, often helps get straighter cases even if you're just doing the traditional FL sizing and depriming in one pass). By setting the expander ball as far up in the neck as I described, you can pick up more support for the case walls, reducing runout. But mostly it helps because you are fully supporting the case head against the shell holder and expanding on the up stroke, not just pulling the necked-down case over the ball, as normal FL sizing does.
Another technique that may or may not make even straighter cases, is to deprime first with the Lee die, then install the RCBS die set to FL size/bump, but with the expander ball drawn up even further into the die. You set it so there is just enough clearance for the case mouth to pass over the expander ball and enter the neck of the die. Let the decapping pin "float" for this. Then, as you withdraw the case from the die, the neck gets expanded on the pull stroke (which I know I said was "bad" just above) BUT, while both the case walls as well as the case neck are still supported.
To know if the steps above are doing you any good or not, you need to have a way of testing how straight your cases are when the process is complete - like a concentricity gauge. But those in a nutshell are two ways to get straighter cases with an RCBS FL sizing die.
Perhaps others have some additional tricks with RCBS dies they can share but those are the only ones I know that only require the small investment in a decapping die.

Hope that wasn't too hard to follow, and it helps.
Rex

 

[asd9055]

You don't want the RCBS NECK EXPANDER plug for bottleneck rifle cartridges - it's for straight-walled pistol cases.

RCBS dies, by their design, actually give you some good options that you would not have with, for instance, Redding (and I really like Redding so that's not a slam on them).

I like using a Lee universal decapper, so if you have one (or can spring for the $16.50 best price on Amazon) use it first, before FL resizing/shoulder bumping with the RCBS decapping rod removed. If you have another set of RCBS dies for a smaller caliber, you can just put that decapping rod in your FL die and go ahead and size/bump and deprime all in one step, but leave the necks unexpanded.
From here reinstall the original, correct for caliber, expander ball. Use its adjusting screw to retract it almost all the way up into the case (since you don't need it to deprime). That, BTW, is the thing Redding die design doesn't allow - they won't retract the expander ball as far up into the die body. The idea is that you will now run your FL sized (but not yet neck-expanded) case back up into the die and expand the neck on the up-stroke. The right height for the expander ball is such that you can push the neck completely over the expander ball without the case mouth entering the portion of the die that sizes it down. Only run the case as far into the die as required to run it over the expander ball, then bring it back out. Your cases may turn out straighter if you leave the decapping rod lock nut loose so the expander ball "floats", and centers itself in the case neck (this, BTW, often helps get straighter cases even if you're just doing the traditional FL sizing and depriming in one pass). By setting the expander ball as far up in the neck as I described, you can pick up more support for the case walls, reducing runout. But mostly it helps because you are fully supporting the case head against the shell holder and expanding on the up stroke, not just pulling the necked-down case over the ball, as normal FL sizing does.
Another technique that may or may not make even straighter cases, is to deprime first with the Lee die, then install the RCBS die set to FL size/bump, but with the expander ball drawn up even further into the die. You set it so there is just enough clearance for the case mouth to pass over the expander ball and enter the neck of the die. Let the decapping pin "float" for this. Then, as you withdraw the case from the die, the neck gets expanded on the pull stroke (which I know I said was "bad" just above) BUT, while both the case walls as well as the case neck are still supported.
To know if the steps above are doing you any good or not, you need to have a way of testing how straight your cases are when the process is complete - like a concentricity gauge. But those in a nutshell are two ways to get straighter cases with an RCBS FL sizing die.
Perhaps others have some additional tricks with RCBS dies they can share but those are the only ones I know that only require the small investment in a decapping die.

Hope that wasn't too hard to follow, and it helps.
Rex

Thanks Rex! After I wrote that I kept researching, and thought maybe sinclair expander mandrel. I was laready thinking about Lee universal decapper. I would only get for the critical for me claibers, 7mm, 30 and 338. But I will try what you said first. I'll check before and after on the sincliar gauge.
Again thanks

 

[TRexF16]

Thanks Rex! After I wrote that I kept researching, and thought maybe sinclair expander mandrel. I was laready thinking about Lee universal decapper. I would only get for the critical for me claibers, 7mm, 30 and 338. But I will try what you said first. I'll check before and after on the sincliar gauge.
Again thanks

The Sinclair mandrel is a good deal (it's what I use) since once you buy the holder die the mandrels are pretty cheap for each caliber. For best neck tension most folks use the "expander" mandrel versus the "turning" mandrel, though both fit the die. The "expander" mandrel gives just a little less neck tension - probably closer to optimum than the "turning" mandrel. Also, no need for carbide mandrels for just neck expanding - the steel ones are fine. I use graphite powder lube for that step but used to use sizing die wax. Either works.

 

[Hugnot]

Let's not complete the sizing process by chambering a loaded round.

 

[Mikecr]

- If the reason a case (and the subsequent loaded cartridge that was made from it) has runout is that the case neck got misaligned with the case body during sizing, and I eliminate that misalignment, why isn't that a legitimate fix?
- Is it your belief that it's not case neck misalignment that is the primary cause of measured case neck runout, but rather a gentle banana curve that runs the entire length of the case?

If the runout is due to necks bent out of case axis, then bending them back would resolve that.
If runout is purely due to bullets seated askew, then nudging their pointing would resolve that.
If runout is due to curving cases, then the only fix is to go back to the root cause of case runout.

The root cause of case runout is sizing of thickness variance. The more of either means higher runout, often growing with each reload cycle.
Cases vary in thickness from webs to mouths. . They also vary in thickness radially. What thickness variance you see at necks runs all the way down to webs. Heavy body sizing and spring back from it adds energy to thickness variance, bringing it into play, causing cases to curve. Same with heavy neck sizing unless the necks are turned to remove thickness variance there.
When you place a case on a v-block and indicate off exposed bullet bearing, all the curves and misalignments register.
You can simply roll cases on a mirror and see it, if you don't have a v-block.

There are a lot of gadgets out there that nudge bullets by pressing against necks while holding bullet tips on a center.
They set indication on the bullet.
The cases behind this are out of measure. Folks using this are not seeing full runout of the loaded cartridge, and they're not actually improving anything as they might think.

What good is it to merely nudge bullets on a long 30-06 banana?
If they're FL sizing, and with a 30-06 they will have to, and if they're sizing thickness variance in their cases, then case runout is growing with each sizing cycle. Eventually that runout may grow to the point of causing chambered tension points. THAT'S when shots throw..
So whether they know why or not, people come to believe they need more chamber clearances. However, it is high chambers clearances that leads to more sizing of thickness variance (feeding the root cause of runout). If they try to resolve high runout with gadgets, while failing to understand what I'm saying here, it's just tail chasing.

The most effective way to reduce runout is:
#1 Cull out new cases with thickness variance, as read with a ball mic at necks.
#2 Plan your chamber/dies/reloading to reduce case sizing.
#3 Reduce chamber clearances to reasonably minimum.
#4 Use a mandrel for pre-seating neck expansion.
#5 Barely seat a bullet, turn the case, barely seat further, turn the case, full seat the bullet.

You may not have control over all this, but you can consider these contributors.
And of coarse there can be problems in your equipment to work out.

 

[Hugnot]

Coarse applications are most likely to fail.

I anneal brass periodically, turn/measure necks, & do not use an expander. Most every time, ammo rolls real good on common axis.

 

[misterc01]

Never heard of Hornady neck bender and have found no such thing in their catalog. As far as nudging the bullet in the Hornady concentricty tool - measurements after show if ti straightend or not.