Problems with Sinclair Runout Gauge

[South Pender]

I've been testing my new Sinclair concentricity gauge and seem to have run into some problems with it. I have an older Bonanza concentricity gauge that I've been using to check it against. Pics below of both, with a dummy 6 PPC round on each:

The problem I'm having with the Sinclair model is in keeping the round properly positioned as I rotate the round on the tool. I've set the dial gauge pointer to have only light pressure on the bullet so as not to tip the round, but even with that and trying to hold the round down on the ball bearings--and back against the stop--I'm having trouble controlling the process.

With the Bonanza tool, the round is held fairly tightly fore and aft by the spring-loaded plunger stop on the head of the case. The V-holder for the bullet allows one to hold the round down the same amount each time when set up properly. It is much easier to use than the Sinclair.

I'm getting very different runout readings from the two tools. On the Bonanza, it is showing about .0015" runout, whereas on the Sinclair, I'm getting more like .006". However, this latter may be more due to my problems discussed above than any actual runout in the round. Just FWIW, the case is an unfired, neck-turned Norma case, with a Bart's 68-gr. 6mm. bullet.

Any thoughts on this?

 

[jerseyjoe]

The Sinclair tool employes the best possible method for measuring true runout of the bullet in a case, and for measuring case neck runout.

I personally use the 21st Century tool, but they use the same method.

It requires a little coordination to hold the round down on the bearings and pushing it against the stop as you spin it, while trying to overcome the spring tension from the indicator.

I would trust the reading from the Sinclair over the Bonanza.

 

[Richard Coody]

Well i have the 21st century and a forster case inspector.

They have much different readings

The sinclair and the 21st century index off of the case itself

The other style index off the bullet tip and the base of the case

They do give different readings. I have yet to have anyone explain which is correct.

 

[jerseyjoe]

This might be easier than me typing it

https://en.m.wikipedia.org/wiki/Run-out

Using the case body as your reference axis will tell you if your bullet is seated crooked
or if your case neck is not concentric with the case body, or both.

Sinclair and 21st Century do this.

 

[ireload2]

The Bonanza tool and all others that use the bullet tip for a dead center do not measure your loaded round as it locates in the chamber.
When you have a crooked bullet you can only see the run out of the neck shoulder or base of the bullet next to the case.
If you consider the case body the primary alignment datum for the round then the 4 ball/roller type gage is the proper design to check the run out of the ogive.

The standard definition of runout is given in the American national standard for Geometric Dimensioning and Tolerancing ASME Y14.5M 2009. It is based on the functional relationship between the feature in question and the functional locating feature (datum).
If you don't understand the how and the why of the standard you might need to take some time to study it. It is the standard that all machined parts are manufactured. Few people outside of inspectors, engineers, designers and machinists are familiar with it. Most take several years to learn it and most never master it.

http://www.gdandtbasics.com/runout/

 

[South Pender]

I guess my concern with the Sinclair tool is that any slight bulge or imperfection in the case behind the shoulder will lead to an indication of run-out. However, this would not index crookedness in the overall round, just an imperfection in the case. Perhaps I'm getting the indication of excessive run-out using the Sinclair gauge because the cases are new and unfired, and might have some imperfections that will disappear with firing, once the case is blown-out in a perfectly round (or nearly so) chamber.

 

[Tim Singleton]

I guess my concern with the Sinclair tool is that any slight bulge or imperfection in the case behind the shoulder will lead to an indication of run-out. However, this would not index crookedness in the overall round, just an imperfection in the case. Perhaps I'm getting the indication of excessive run-out using the Sinclair gauge because the cases are new and unfired, and might have some imperfections that will disappear with firing, once the case is blown-out in a perfectly round (or nearly so) chamber.

Now your on to it
You have to have cases fully formed 4-5 X fired.
Check unsized fired case necks hopefully chamber is good and this is close to zero. Then check sized cases to see what amount of runout the sizing die is introducing hopefully this is 3- 10,000 or less.
Then checked seated bullet to see how much more imperfection the seater is introducing

 

[ireload2]

Any bulge in the case behind the shoulder will affect the position of the case in the chamber. Any defects from "perfect form" affect the location of the case when chambered. That is the benefit of using functional gaging. It gives you the exact same reading as if you were measuring runout on chambered ammo.

Naturally never fired cases will give you a different reading when they have minute defects that are blown out by fire forming. But that is why you fire form. You improve the fit of the brass in your chamber.

I guess my concern with the Sinclair tool is that any slight bulge or imperfection in the case behind the shoulder will lead to an indication of run-out. However, this would not index crookedness in the overall round, just an imperfection in the case. Perhaps I'm getting the indication of excessive run-out using the Sinclair gauge because the cases are new and unfired, and might have some imperfections that will disappear with firing, once the case is blown-out in a perfectly round (or nearly so) chamber.

 

[South Pender]

Now your on to it
You have to have cases fully formed 4-5 X fired.
Check unsized fired case necks hopefully chamber is good and this is close to zero. Then check sized cases to see what amount of runout the sizing die is introducing hopefully this is 3- 10,000 or less.
Then checked seated bullet to see how much more imperfection the seater is introducing

I'll be neck-sizing only with the Wilson chamber-type die and bushing. So there will be no pulling the necks off-center with a press-mounted sizer that has an expander ball. I'll try this again once I've fired the cases. And perhaps some practice with the Sinclair tool in holding the cases down and back against the stop will help.

 

[ireload2]

One thing you can do with the new brass. Sort the loaded rounds into a little to no runout pile and into a excessive runout pile. Shoot groups with each and see if you can tell any difference.

 

[Tim Singleton]

I'll be neck-sizing only with the Wilson chamber-type die and bushing. So there will be no pulling the necks off-center with a press-mounted sizer that has an expander ball. I'll try this again once I've fired the cases. And perhaps some practice with the Sinclair tool in holding the cases down and back against the stop will help.

Let us know how they look. My neck bushing die introduce about 6/7-10,000
I'm thinking about investing in custom full length non bushing die in hopes of eliminating some of the runout from the bushing

 

[South Pender]

Let us know how they look. My neck bushing die introduce about 6/7-10,000
I'm thinking about investing in custom full length non bushing die in hopes of eliminating some of the runout from the bushing

That's interesting, Tim. I had thought that the Wilson bushing die (with no expander) would have introduced next-to-no runout in the case.

 

[Tim Singleton]

That's interesting, Tim. I had thought that the Wilson bushing die (with no expander) would have introduced next-to-no runout in the case.

I think, in my case anyway it's the bushings themselves. I've checked them with the bushing out. Went thru several bushings

 

[nmkid]

I took a 3/4" piece of wood about 6" long and ran it several times through a small planer to try and get it squared up as much as feasibly possible. Then I took a piece of bike inner tube, cut it to size and glued it to the stick. Now I just drag it across the case with pretty even pressure. Works good for me.

 

[SheepDog]

The measurement of runout with the Sinclair tool should always be greater than a tool that measures the runout between the base and the bullet tip. One supports the case (Sinclair) and the other floats the case in relation to a centerline from the tip to the base. Think of a stick with a bend in it. If you spin it supported by the ends you get 1/2 the bend =/- as it rotates. if you support that same stick by one end so that the other end makes the full arc then you measure the whole bend =/- which means if the stick has a bend that is six inches off center between the ends you will measure 3" up and three inches down for a total of 6". Now if you support the stick at one end (square to that end) the other end of the stick will wobble 6" up and 6" down for a total of 12" of measured runout. The Sinclair tool assumes the case has no runout. it also effectively doubles the measured movement.
For an accurate measurement of runout you have to start with case runout between the neck and the base and then compare that to the position and amount of runout at the bullet. I know that my case is supported at the base and at the neck in my chamber within about .001" clearance so the only runout I am concerned with is the bullet alignment to that axis. If I had a case that flopped around in the chamber there would be no reference unless the bullet was jammed into the rifling and the bolt face was jammed into the base of the cartridge. It is likely that such an alignment would provide better alignment but in at least one of my guns I would need to run the longest bullet possible to hit the rifling. It just isn't worth that cost to me.

 

[T-shooter]

I've been testing my new Sinclair concentricity gauge and seem to have run into some problems with it. I have an older Bonanza concentricity gauge that I've been using to check it against. Pics below of both, with a dummy 6 PPC round on each:

The problem I'm having with the Sinclair model is in keeping the round properly positioned as I rotate the round on the tool. I've set the dial gauge pointer to have only light pressure on the bullet so as not to tip the round, but even with that and trying to hold the round down on the ball bearings--and back against the stop--I'm having trouble controlling the process.

With the Bonanza tool, the round is held fairly tightly fore and aft by the spring-loaded plunger stop on the head of the case. The V-holder for the bullet allows one to hold the round down the same amount each time when set up properly. It is much easier to use than the Sinclair.

I'm getting very different runout readings from the two tools. On the Bonanza, it is showing about .0015" runout, whereas on the Sinclair, I'm getting more like .006". However, this latter may be more due to my problems discussed above than any actual runout in the round. Just FWIW, the case is an unfired, neck-turned Norma case, with a Bart's 68-gr. 6mm. bullet.

Any thoughts on this?

The reason you are getting different reading is the way each tool is set up. The round is supported from different points. With the Sinclair, put a little case lube on the ball bearings and be sure to keep a fair amount of pressure on the case. It your cases have any dents near the shoulder, you cannot use it in this way.

 

[BoydAllen]

On the Sinclair, to my eye it is not set up correctly. The front support should be closer to the shoulder. If you want a better reading use the edge of a long hard eraser to turn the case on the tool, and angle it slightly so that the case is pushed slightly to the rear against the stop. This gets away from the disturbance of the first joint of your index finger passing over the case body as you rotate it. The other way to get around the problem is to use two hands to turn the case. It takes a little practice, but it will result in a smoother turning. I have both types of gauges, a H&H that supports off of the bullet tip, and is designed to straighten, and an older Sinclair that supports cases like the newest model, on bearing balls that contact the case body. Their readings vary because they support differently, but no matter which one you use, straight measures straight, and crooked measures crooked.

 

[South Pender]

Thanks a lot, guys, for your patience and helpful advice. I decided to do another test with the Sinclair tool and measured runout with the gauge tip at two positions: (a) midway in the case neck and (b) out on the ogive of the bullet. The amount of runout was much less when measured on the case neck than when measured on the bullet. Boyd, I tried using both hands as you suggested, and that seemed to make the process easier.

 

[T-shooter]

Thanks a lot, guys, for your patience and helpful advice. I decided to do another test with the Sinclair tool and measured runout with the gauge tip at two positions: (a) midway in the case neck and (b) out on the ogive of the bullet. The amount of runout was much less when measured on the case neck than when measured on the bullet. Boyd, I tried using both hands as you suggested, and I that seemed to make the process easier.

The way I measure is about half way from the end of the bearing surface to the tip. This will show any alignment issues with the bullet vs the case. It will show a higher reading than measuring in other places but that doesn't matter. I feel good with .001" or less here, .002" not bad, .003" is about my upper limit for accuracy ammo. This would be with cases previously fired through my rifle and resized.

 

[BoydAllen]

Thanks a lot, guys, for your patience and helpful advice. I decided to do another test with the Sinclair tool and measured runout with the gauge tip at two positions: (a) midway in the case neck and (b) out on the ogive of the bullet. The amount of runout was much less when measured on the case neck than when measured on the bullet. Boyd, I tried using both hands as you suggested, and that seemed to make the process easier.

Glad to be of help. Generally the runout that you see is the neck being cocked in relation to the case body. When the bullet is seated it follows the neck along the same angle. For this reason, the farther out from the neck shoulder junction that you take your measurement, the greater it will be. Out near the bullet's tip will be the largest amount of runout. In order to make comparisons it is a good idea to standardize where you take your measurements. For short bullets in .22 and 6mm I usually take mine about .150 - .175 from the end of the case.