RCBS FL neck ID size question 308

[callen3615]

Hi, I noticed today that my neck tension varies wildly from the cases I have just neck sized to the cases I FL resized.

My neck sizing die is a lee, my FL sizer is a rcbs.

I took to measuring, after FL sizing with the rcbs the inner diameter of the neck is .304 (308win). I tried backing the die out abit, no change.

My neck sizer leaves them around.307.

Whats the deal guys?

 

[Fuzzball]

Re: RCBS FL neck ID size question 308

"Whats the deal guys?"

Well, you've learned that you can't change the diameter of a sized case neck by how far you push it into the FL die - or a common neck die for that matter. Next, you've learned that different die types produce different neck diameters. Sounds like you're measuring your FL sized necks without use of an expander. If so, put it back in and do your test again.

There's a significant difference between neck "tension" and bullet grip. Your Lee Neck sizer is giving you all the real grip any sizer can give you, anything smaller just makes seating harder and increases bullet runout without any real difference in bullet grip. Bullet runout is NOT helpful to accuracy.

 

[FLIGHT762]

Re: RCBS FL neck ID size question 308

The lee collet neck sizer uses collet to squeeze the case neck around a mandrel. Depending on what your brass neck thickness is, this will determine how tight your neck tension will be. You can do a couple of things. You can polish the lee mandrel down .001" to get tighter neck tension or call Lee and order a smaller .30 cal mandrel that they offer. It's only about $6.00. To get tighter neck tension on Federal cases, I polished my Lee mandrel down .001" to get tighter neck tension on a variety of brass.

Federal 308 brass has thick necks, Winchester 308 brass has thinner necks.
The F/L die sizes the neck of the brass down smaller to minimum dimensions (your .304" size), then on the up stroke of the press, the expander ball is run through the neck to open the neck up to .306" or so. This is why you will feel tighter neck tension when using the F/L die with the expander ball.

What brass are you using?

 

[callen3615]

Re: RCBS FL neck ID size question 308

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">The lee collet neck sizer uses collet to squeeze the case neck around a mandrel. Depending on what your brass neck thickness is, this will determine how tight your neck tension will be. </div></div>

This I understand

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">
Federal 308 brass has thick necks, Winchester 308 brass has thinner necks.
</div></div>

This I also understand. I dont have much federal, and what I do have a download 2 tenths of a grain and dont expect much from them accuracy wise.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">
The F/L die sizes the neck of the brass down smaller to minimum dimensions (your .304" size), then on the up stroke of the press, the expander ball is run through the neck to open the neck up to .306" or so. This is why you will get more uniform neck tension when using the F/L die with the expander ball.
</div></div>

So why are my cases ID 2 thousandths smaller than that? Could my expander ball be out of spec? I dont anneal BTW, my brass doesnt have more than 2 FL sizings. I need to get better about record keeping, but I dont think I have more than 4 firings on any of my brass.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">
What brass are you using?
</div></div>

Remington, winchester, some older PMC that I have saved. Maybe 20 federal cases.

I dont mix head stamp. I will load up 20 or so of the same brands and try not to cross contaminate when I shoot.

The remington and federal cases seem to be thicker in general than the pmc and winchester.

The RCBS die seems to leave everything around .304-.305. I dont want to move it much more than 1-1.5 thou. At .304 bullet seating seems too hard, too much tension.


BTW thanks for the help.

 

[callen3615]

Re: RCBS FL neck ID size question 308

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body"> Bullet runout is NOT helpful to accuracy. </div></div>

Im not a GD&T wizard but runout is likened to concentricity correct?

 

[callen3615]

Re: RCBS FL neck ID size question 308

Just measured my expander ball diameter. .3055.

I also sized 3 different brands of brass in the RCBS. Then measured the ID of the neck.

Fed----.304-.3045
PMC----.3045-.305
Win----.305-.3055

 

[FLIGHT762]

Re: RCBS FL neck ID size question 308

You can measure your expander button and see if it's a bit too small. Also, the brass will spring back differently depending how muck work hardening has occurred. That is why some shooters anneal.

If you are getting too muck neck tension in the F/l die you can try to get a little bigger expander ball or spend $35.00 and get a Redding F/L body only die. Some reloaders find that dragging the expander ball through the neck can cause excessive run out. Some can do it without too much run out.

I use a Redding body die with the Lee N/O collet die. It makes very accurate ammo. Use the body die when you need to F/L size & bump the case shoulders back after 3-4 neck only firings. I would do this since it cost effective. The other way to control neck tension is to go to a bushing die set up. which can get expensive @ 23.00 per bushing.

I have a full array of Redding S bushings with their dies and can control neck tension, but I make just as accurate ammo with the Lee N/O collet die and the Redding F/L body only die.

Are you getting poor accuracy when using the F/L die? Do you get better accuracy after firing the F/L cases and then load using the Lee N/O collet die?

**EDIT** I see you measured the expander ball, I'n not near my reloading room to measure some of my .30 cal expander balls. It takes me a while to type.

 

[callen3615]

Re: RCBS FL neck ID size question 308

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">
I use a Redding body die with the Lee N/O collet die. It makes very accurate ammo. Use the body die when you need to F/L size & bump the case shoulders back after 3-4 neck only firings. .

</div></div>

I really like the idea of this. I already have a lee collet neck sizer. So with this I can just bump the shoulder back every 3/4 firings and leave all the other case dimensions alone? Do you need to lube cases with that die? So in theory I can resize just the neck with the lee collet die and have the same ID every time?

I might just do that.

 

[FLIGHT762]

Re: RCBS FL neck ID size question 308

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cpt. obvious</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">
I use a Redding body die with the Lee N/O collet die. It makes very accurate ammo. Use the body die when you need to F/L size & bump the case shoulders back after 3-4 neck only firings. .

</div></div>

I really like the idea of this. I already have a lee collet neck sizer. So with this I can just bump the shoulder back every 3/4 firings and leave all the other case dimensions alone? Do you need to lube cases with that die? So in theory I can resize just the neck with the lee collet die and have the same ID every time?

I might just do that. </div></div>

Yes, that's the die. You can even get a small base one if you want to:

http://www.midwayusa.com/product/378388/redding-small-base-body-die-308-winchester

 

[callen3615]

Re: RCBS FL neck ID size question 308

Those are for firearms with tight chambers correct? I dont think my 700 qualifies. lol