Adjusting neck tension

[marchboom]

I'm considering using pin gauges to adjust neck tension. Start with a Lee Collet Die or a FL die that gives about .002" (or more) neck tension. Then use pin gauges in a press mounted holder in .0005" steps to increase the inside diameter thereby decreasing the neck tension. Would probably stop at .001" neck tension. Hopefully this would reveal at least one group that would show an accuracy improvement. I'm shooting .223, 22-250 and 22-250 AI. Also a .308 with a tight chamber.

Has anyone used this method with any success or am I wasting my time?

Thanks

 

[jepp2]

Has anyone used this method with any success or am I wasting my time?

These are the things I do to adjust/control case neck tension:
- Hone the necks of my FL sizing dies
- Buy undersize mandrels from Lee for my LCD
- Use the 21'st Century expanders mostly to move the irregularities from the inside of the neck to the outside
- Use Whidden bushings in my Whidden and Redding bushing dies

Questions I have about your approach:
-If you are going to use pin gages, how do you plan to "bevel" the leading edge?
-Most FL sizing dies seriously undersize the case necks, just to make sure they can deal with everything. How much are yours undersizing that you need to expand? My experience says that if the sizing die expander (no matter how high you set it) has to increase the case neck more than about 0.0015", it will pull the neck off center - inducing runout. I don't have experience measuring runout with large expansions using other expanders.

I find more things that yield larger results than case neck tension. I normally goal for 0.002" neck tension, but might run less if I have enough bullet seating depth. I don't really favor using the bullet as an expander for greater neck tension. But that is just me.

 

[Lucky Shooter]

Just for grins----has anybody tried using pin gages for the collet die mandrel-----followed by gaging
the neck ID with other smaller pin gages-----and maybe eliminating the need to expand the necks ?

Class ZZ pin gages (.0002 tolerance, .0005 increment) aren't terribly expensive.

This is one of the things I'm chasing now but I haven't produced answers.

A. Weldy

 

[T-shooter]

For .308, I use a K&M expander which is polished to .3080". There is usually about .001" springback to I get a good fit. On some that the expander feels a little tighter in (my resizing die leaves the fit at about .002"), I run it in twice or leave it in the expander for a minute or two. If that doesn't do it, they get annealed. I also got a slightly larger mandrel & holder for my Lee Collet Die (I forget, maybe for a .303 or .762) and polished it down to the same dimension.

 

[AJC]

I would think that you would need to start from a dimension with a much larger difference like straight out of your sizing die I don't know if a change of .0005 would get you to the plastic point for actual sizing. Very curious myself what that minimal amount would be, knowing it would change with every lot based on brass formulas.

 

[Uncle Ed]

At the Whidden die website, they sell expander kits for standard full length dies. The five expanders are in .001 increments from bullet diameter to .004 under bullet diameter.

You could also order the expanders from who made your dies and polish them to your desired diameter.

 

[butchlambert]

I use carbide neck bushings with .0005" increments. I have 11 bushings in each caliber from 224,243,264, and 308. Yes, I also have Deltronic Pins, but I only use then in brass to check neck ID if I feel a need.

 

[dgeesaman]

Using the pins with .002” max neck tension, might not resize the necks at all. When sizing necks, some portion of the sizing stretches right back and the rest stays permanently.

How much of each depends on how hardened the brass is. Annealed changes shape the most.

Feel free to experiment. Sometimes the theory (change of neck tension) does not offer improvements but a benefit arrives for other reasons. Perhaps roundness.

At a minimum I’d start with .003 neck tension. Maybe using annealed brass with your existing die will get you there.

David

 

[David Christian]

I'm considering using pin gauges to adjust neck tension. Start with a Lee Collet Die or a FL die that gives about .002" (or more) neck tension. Then use pin gauges in a press mounted holder in .0005" steps to increase the inside diameter thereby decreasing the neck tension. Would probably stop at .001" neck tension. Hopefully this would reveal at least one group that would show an accuracy improvement. I'm shooting .223, 22-250 and 22-250 AI. Also a .308 with a tight chamber.

Has anyone used this method with any success or am I wasting my time?

Thanks

Hi @marchboom. I think you should definitely continue your exploration with the gage pins.

In my experience, combined with consistent annealing, gage pins provide a very consistent neck. I anneal with an amp after each firing and then use a .2840 pin (.284 caliber) before seating each bullet. I find my spring back to be only .0005, meaning my interference fit is a 1/2 thousand. Over the last two years of diligently taking notes, always using my chrono, and following this process, I have determined that the pins are a major contributor to shooting 20 shot strings and averaging a 15-20 ES.

Related to your process, I would think about sizing the brass as minimal as possible. I use bushing dies and will find the bushing that provides the least amount of sizing (1.5 thousands or less), then use the appropriate pin gage to slightly expand the neck back out.

report back what you find.

 

[Ralph Littlefield]

I'm considering using pin gauges to adjust neck tension. Start with a Lee Collet Die or a FL die that gives about .002" (or more) neck tension. Then use pin gauges in a press mounted holder in .0005" steps to increase the inside diameter thereby decreasing the neck tension. Would probably stop at .001" neck tension. Hopefully this would reveal at least one group that would show an accuracy improvement. I'm shooting .223, 22-250 and 22-250 AI. Also a .308 with a tight chamber.

Has anyone used this method with any success or am I wasting my time?

Thanks

Can you elaborate on the "press mounted holder"? Will a collet type bullet puller be adequate for that?

 

[dmoran]

Can you elaborate on the "press mounted holder"? Will a collet type bullet puller be adequate for that?

Yes, the collet bullet pullers work well with pin gages for expanding (as do custom made collet expanders).
Floating the puller or die aides in alignment and concentric's.
Some grind a chamfer on the leading edge of the pins, some don't.

 

[DHuffman]

Yes, the collet bullet pullers work well with pin gauges for expanding (as do custom made collet dies).
Floating the puller or die aides in alignment and concentric's.
Some grind a chamfer on the leading edge of the pins, some don't.

When you say floating the puller do you mean leaving it loose? How loose?

How about a Lee die nut with the rubber O ring ran in to lightly touch to take the wobble out but still allow it to align to the neck?

 

[dmoran]

How about a Lee die nut with the rubber O ring ran in to lightly touch to take the wobble out

Perfect ...... O-rings is my way as well, and for everything !.!.!

 

[dmoran]

Myself use a Forester Bullet Puller with Vermont or Shars Pin Gages




For a custom made collet expanding die, http://portersprecisionproducts.com is one of the places that make/sell them.
(Atten: @Joe R - could you put up a picture(s) showing your custom expander setup).

 

[dgeesaman]

Myself use a Forester Bullet Puller with Vermont or Shars Pin Gages

View attachment 1153357

For a custom made collet expanding die, http://portersprecisionproducts.com is one of the places that make/sell them.
(Atten: @Joe R - could you put up a picture(s) showing your custom expander setup).

How do you expand with those gage pins if they don’t have a chamfer on one end?

(I used gage pins that I chamfered myself but changed over to 21st century/Sinclair style because they don’t hang up at all.)

David

 

[Jdne5b]

I use one from Steve Jennings and the 21st century. They both work as intended

https://sjr-enterprises.com/

 

[mike a]

I use carbide neck bushings with .0005" increments. I have 11 bushings in each caliber from 224,243,264, and 308. Yes, I also have Deltronic Pins, but I only use then in brass to check neck ID if I feel a need.

Hi Butch, carbide neck bushings in .0005 from where? Will they fit my Redding bushing dies? I would like to get away from expanders. Mike

 

[marchboom]

I plan to put a gradual, polished taper on the pins so it goes into the case easy. I have a Forster bullet puller that will be the mandrel holder. I installed a pin in this holder and it locks down on it with authority. Wasn't sure if the puller would have enough bearing surface area but it did. It was rock solid. Now I will have to see if it likes to be locked down solid to the press or be allowed to float.

With the RCBS FL sizer die and the Lee Collet die the inside of the next comes out to .223". But I would like to try different amounts of tension to see what various bullet/powder combinations like.

I really appreciate everyone's input to my thread. Several gave me additional things to think about.

 

[dgeesaman]

Not being chamfered, has never been an issue for me (cases are chamfered). I also have/use K&M expander mandrels for neck-turning, but use Pin gages for setting neck tension desires (custom sizes and cheaper then mandrels). Note: I do not use lube, but "brush polish" the necks first.

Interesting.

I have brushed my necks and without sizing wax or dry neck lube, the pins grab the brass hard. I also need to be very careful to ensure the brass mouth is perfectly centered on the pin. The amount of movement in the die and case holder are much greater than the size of a case mouth chamfer.

Of course this is the Internet but it would be enlightening to compare my gage pin expander setup to yours, maybe I'm missing something. In any case I’m sticking with my 21st Century / Sinclair setup for expanding and using my gage pins for gaging.

David

 

[Webster]

I'm considering using pin gauges to adjust neck tension. Start with a Lee Collet Die or a FL die that gives about .002" (or more) neck tension. Then use pin gauges in a press mounted holder in .0005" steps to increase the inside diameter thereby decreasing the neck tension. Would probably stop at .001" neck tension. Hopefully this would reveal at least one group that would show an accuracy improvement. I'm shooting .223, 22-250 and 22-250 AI. Also a .308 with a tight chamber.

Has anyone used this method with any success or am I wasting my time?

Thanks

You need to have very good shooting skills and a rifle that can consistently shoot 1/4" groups. If a shot is 0.040" out of the group how could you determine what caused it?