Pin gauge fitment in case neck

[savageshooter86]

So when using pin to determine ID for setting up neck tension using a dedicated expander die that uses pin gauges for this step, how do you know which pin is the correct ID size? For instance 3045 slides all the way in case freely. 305 goes into the neck and stops just shy of the neck/shoulder under case but can tell next size probably won’t fit. 3055 just barely will start the taper at the mouth. So that’s too large of a pin. So which pin would you say is proper and write down as ID?

Thanks

 

[Dos XX]

Is the .305 hitting a donut, or is it being stopped by a cushion of air? If it is a cushion of air, it will feel springy when you push and pull on it like the down movement is being cushioned and the up movement is drawing a vacuum. That's the one I use.

 

[TaperPin]

In general, if your bullet goes all the way in, your pin should as well.

 

[savageshooter86]

Is the .305 hitting a donut, or is it being stopped by a cushion of air? If it is a cushion of air, it will feel springy when you push and pull on it like the down movement is being cushioned and the up movement is drawing a vacuum. That's the one I use.

Edited: so with primer in or covering primer pocket it does have cushion of air. And 305 goes in can feel it touching the neck barely. It goes all the way in but does have a cushion feel we are talking about.

 

[Dos XX]

In general, if your bullet goes all the way in, your pin should as well.

If his bullet went all the way in, he wouldn't have any neck tension, would he? Or, am I misunderstanding? Not uncommon for me.

 

[Dos XX]

No cushion of air.

.30455? Kidding.

So, the .3045 would fall in all the way to bottom of the case? It seems odd to me that the .305 goes all the way to the neck shoulder junction, like your neck is tapered? I don't know. I haven't run into that before. If you are using a bushing die, the part of the neck down there doesn't get sized, does it?

 

[RegionRat]

So when using pin to determine ID for setting up neck tension using a dedicated expander die that uses pin gauges for this step, how do you know which pin is the correct ID size? For instance 3045 slides all the way in case freely. 305 goes into the neck and stops just shy of the neck/shoulder under case but can tell next size probably won’t fit. 3055 just barely will start the taper at the mouth. So that’s too large of a pin. So which pin would you say is proper and write down as ID?

Thanks

What you are describing is some taper and elasticity, and those are just the facts of life when we work in a lab and try to measure things like case necks.

Even when in a laboratory where we can map the ID and OD to the fifth and sixth decimal point using methods like CMM or FormScans, the gage force can affect the answer. When we use non-contact optical methods, that gage force issue is gone.

Just keep checking and don't fixate on the idea that you get a single exact answer.
When there is thickness, or hardness gradient in the necks, you will usually detect some taper and out of round. Just be honest with yourself about the amount of force or drag you are using when the pins get tight.
Pick the one you want to call the size, but in your notes it is fair to talk about the drag on the pin.

Your work with pins in 0.0005" steps is good enough to get control of your prep process.

 

[savageshooter86]

.30455? Kidding.

So, the .3045 would fall in all the way to bottom of the case? It seems odd to me that the .305 goes all the way to the neck shoulder junction, like your neck is tapered? I don't know. I haven't run into that before. If you are using a bushing die, the part of the neck down there doesn't get sized, does it?

I edified. I just checked again and covered the primer pocket with finger. 3045 has that springy cushion feel. 305 goes in all the way but can barely feel it touching the necks going in all the way.

 

[Dos XX]

I edified. I just checked again and covered the primer pocket with finger. 3045 has that springy cushion feel. 305 goes in all the way but can barely feel it touching the necks going in all the way.

That makes sense. I use my mandrel for final neck size after I prime the brass. It is the last thing before adding powder and seating a bullet.

 

[Firearmsunlimited]

It sounds like a complicated way to establish neck tension. Mic the neck wall, multiply it by 2, add the bullet diameter to get "0" neck tension. For a .002 tension subtract .002 from your "0" measurement.

 

[savageshooter86]

That makes sense. I use my mandrel for final neck size after I prime the brass. It is the last thing before adding powder and seating a bullet.

Mine too. Just switched to Porters Die set up and pins vs standard resizing mandrel process I’ve been using. Just wanting to try something new. But prior I never even measured. Just used the expander mandrel I thought and never checked or tested any other size. So now it’s want to experiment with different tensions and see if it helps

 

[memilanuk]

It sounds like a complicated way to establish neck tension. Mic the neck wall, multiply it by 2, add the bullet diameter to get "0" neck tension. For a .002 tension subtract .002 from your "0" measurement.

That way involves a certain amount of guess-work regarding the spring back of the case neck after sizing and/or expanding.

Once you check it with some pin gages, you begin to realize that you literally *were* guessing before.

 

[RegionRat]

It sounds like a complicated way to establish neck tension. Mic the neck wall, multiply it by 2, add the bullet diameter to get "0" neck tension. For a .002 tension subtract .002 from your "0" measurement.

He was past that point and is trying to measure the result of such a process using his other pins.

In labs we use Deltronic pins to inspect, and on the factory floors we issued go and no-go pins for the same purpose. We had even more sophisticated methods, but the pins were more convenient and easier to manage.

 

[David Christian]

So when using pin to determine ID for setting up neck tension using a dedicated expander die that uses pin gauges for this step, how do you know which pin is the correct ID size? For instance 3045 slides all the way in case freely. 305 goes into the neck and stops just shy of the neck/shoulder under case but can tell next size probably won’t fit. 3055 just barely will start the taper at the mouth. So that’s too large of a pin. So which pin would you say is proper and write down as ID?

Thanks

I am going to answer this in a slightly different manner. I read the OP as asking what size pin gage to use to set neck tension. If that is the correct question, here is how I do it (using OP’s dimensions).

Post sizing you are getting an ID measurement of .305. Therefore I would use a .307 sized pin, as I want the brass to move .002 in the expansion process. If the brass does not move beyond its yield point, I see great variation in the final ID. I anneal after each firing so after using the gage pin my new ID should be .3065 to .3070 depending on spring back. This would leave me .001 to .0015 neck tension.

If I wanted more neck tension I would use a smaller bushing, and then a .306 pin to produce .002 to .0025 final tension, or an even smaller bushing and a .305 pin for even more final neck tension. Whatever bushing size I use, I pair it with a pin .002 larger than the ID neck size.

 

[rwj]

A warning when using pins to measure… they can only detect the smallest internal diameter. Wall thickness variation and lack of roundness will cause other areas to be larger. The amount of interference fit will determine how much bullet contact there will be in these larger areas. When the fit is small (~0.0005”) there could be none!

 

[COLT45SA]

Is the .305 hitting a donut, or is it being stopped by a cushion of air? If it is a cushion of air, it will feel springy when you push and pull on it like the down movement is being cushioned and the up movement is drawing a vacuum. That's the one I use.

What cushion of air~?? If I haven't yet re-primed the case I suspect that the open flash hole will prevent any air from being trapped and there won't be any cushion~!!

 

[savageshooter86]

I am going to answer this in a slightly different manner. I read the OP as asking what size pin gage to use to set neck tension. If that is the correct question, here is how I do it (using OP’s dimensions).

Post sizing you are getting an ID measurement of .305. Therefore I would use a .307 sized pin, as I want the brass to move .002 in the expansion process. If the brass does not move beyond its yield point, I see great variation in the final ID. I anneal after each firing so after using the gage pin my new ID should be .3065 to .3070 depending on spring back. This would leave me .001 to .0015 neck tension.

If I wanted more neck tension I would use a smaller bushing, and then a .306 pin to produce .002 to .0025 final tension, or an even smaller bushing and a .305 pin for even more final neck tension. Whatever bushing size I use, I pair it with a pin .002 larger than the ID neck size.

David thanks for the reply. This is what I am doing except I have a FL die. So can’t adjust bushing to get close before expanding. I was also asking how you tell using the pin to determine ID? Should the pin just barely touch the neck going in? Should it have more than just barely touching? I assume now it should have some contact with inside neck for determining proper ID to set all this up. Looking for how the pin should fit in the neck to determine it’s the proper size vs the next size down.

 

[RegionRat]

Should the pin just barely touch the neck going in? Should it have more than just barely touching? I assume now it should have some contact with inside neck for determining proper ID to set all this up. Looking for how the pin should fit in the neck to determine it’s the proper size vs the next size down.

The step size of your pin set will limit your ability to get too fancy with this.

When your pins step in 0.0005" increments, your feel will be based on the quality of the brass and the defects in your necks.

When a pin slides straight in and doesn't feel tight, step up to the next one.
Never use a dry pin.
Be sure to leave the pin slightly lubricated with sizing lube to avoid sticking.

When the next pin up seems like it takes torque and force to push in and out, you have to use some judgement to establish your own standard for calling the size either the last pin you could push in without grunting, or the one before. It is arbitrary so just be consistent.

In industrial work, we have pin sets that step in 0.0001" increments. We also train the techs based on handing them blind tests of samples we have measured with much more sophisticated methods to give them a feel for the pins.

It is easy when the brass is virgin with good finish and geometry, but more difficult when it is rough and out of shape. The elasticity of the case neck is magic compared to many other challenges, but it takes some practice to get a technician "calibrated" with gage pins in different types of context and metals.

Don't let this scare you, just get rolling and be consistent, taking good notes. Don't call one while slipping the pin in and out loose like a trombone one day, and use lots of force the next. There would only be roughly 0.0005" difference between a loose pin and a pin that takes effort to slide in and out. With some practice, you will get the hang of this fast.

The challenge is to learn to detect chamfer, contamination, burrs, etc., and tell the difference between those and the actual ID. You are reloading used brass versus setting up a virgin production line, so you will detect powder residue and your chamfer workmanship and soon you will be able to tell the difference.

Practice on some virgin brass to get a better feel, then also try to gage some fired-unsized brass if you have the pin range.

Happy New Year!

 

[David Christian]

David thanks for the reply. This is what I am doing except I have a FL die. So can’t adjust bushing to get close before expanding. I was also asking how you tell using the pin to determine ID? Should the pin just barely touch the neck going in? Should it have more than just barely touching? I assume now it should have some contact with inside neck for determining proper ID to set all this up. Looking for how the pin should fit in the neck to determine it’s the proper size vs the next size down.

For the work we do, you might be over thinking the “exact”pin size dimension. As @RegionRat stated above, test what pin fit feels right, then use a pin .002 larger to set final neck tension. I know bushing dies are sometime shunned on this forum, I find the ability to gradually step down the sizing with various bushing sizes relevant to using different pin gages and ultimately testing different final neck tensions.

 

[savageshooter86]

Appreciate the replies. I got the answers I needed. Thanks for the input and tips