300 Win Neck Tension Question

[Hot Karl]

So I anneal, Full length resize with Redding bushing dies, the works. My question is I have become very doubtful of the expander balls inside the die. So I have been wanting to use a 21st century mandrel to expand my necks right after chamfer and debuting. MY question is to achieve .002 neck tension, am should I be sizing the neck down with the bushing to .004 then bumping up by .002 with the mandrels? Reason I ask is I have been having some rather inconsistent neck tension in my brass. Some seat great, others not so much and can be moved by small pressure. No I am aware neck turning will play an important role in this, and the brass I currently am working with was just turned. I just am trying to get more consistent neck tension and am seeing if anyone else has some tips or if they use the mandrels and get very good results? Thanks

 

[straightshooter1]

I've experimented with my .308 cases in trying to get my case as uniform and true (true = neck runout less than .001). My experience with bushing dies is that the bushing induces additional runout on a case that's been fired. And and expander ball does the same. Those two thing together put way more runout on the neck than I wanted. Running a bushing die without the expander ball helps a lot, but then running an expander mandrel afterwards, doesn't help much to improve the runout after sizing with a bushing die. So, what I found that works really well for me is I use a Forster FL sizing die without the expander ball and run an expander mandrel afterwards, which give me very close to the same runout on the neck as it is right after firing (less the .001, typically ~ .0005).

I turn my necks also, but in comparing my turned necks to those that were not, where I've sized the cases as I like, I found doing so doesn't really make much difference in runout. The variances in neck thickness can give you a false runout measurement on the neck when the expander mandrel moves the variances in neck thickness to the outside where runout is measured.

When the necks are not turned, a bushing die will move the variances in neck thickness to the inside, which can result in runout on the bullet that's not acceptable. But if you turn thee necks, then there's no (or very little) variance to be moved anywhere. But the bushing in a die still tens to induce some runout.

I've heard people claim they get good results with a bushing die (or at least acceptable results), but that just wasn't my experience with them.

 

[spife7980]

MY question is to achieve .002 neck tension, am should I be sizing the neck down with the bushing to .004 then bumping up by .002 with the mandrels?

Yep, that’s the process. Generally the “turning arbor” is what you’re after as it is .002” below bullet diameter. The “expander mandrel” is .001 under bullet diameter.

 

[Sig Marine]

So I anneal, Full length resize with Redding bushing dies, the works. My question is I have become very doubtful of the expander balls inside the die. So I have been wanting to use a 21st century mandrel to expand my necks right after chamfer and debuting. MY question is to achieve .002 neck tension, am should I be sizing the neck down with the bushing to .004 then bumping up by .002 with the mandrels? Reason I ask is I have been having some rather inconsistent neck tension in my brass. Some seat great, others not so much and can be moved by small pressure. No I am aware neck turning will play an important role in this, and the brass I currently am working with was just turned. I just am trying to get more consistent neck tension and am seeing if anyone else has some tips or if they use the mandrels and get very good results? Thanks

Spife7980 gave you the answer to your specific question but from my experiences, I'll analyze the problem from a different perspective. First, a few questions:
What brass are you using?
How do you clean your brass?
Do you brush/clean the inside of your necks after annealing?
Do you lube inside the necks BEFORE dropping powder and seating bullets?

I have found the above important because the quality of brass you are using is going to have a bearing on the consistency of your neck wall thicknesses. I use Lapua brass so my testing, listed below, was done with brass known for having consistent walls. How you clean your brass also has a bearing on neck tension as methods using stainless pins or ultra-sonic cleaners will get the inside of the necks extremely clean. This brings up using a dry lube on the inside of the necks before dropping powder and seating bullets. Also, if you use a vibrator or wiping method of cleaning, then the carbon left in the necks gets torched in the annealing process and should be brushed before using lube.

I've tested sizing using FL sizers with bushings (Redding Type "S") AND without bushings (Forster), with an expander ball, sizing and using a mandrel, sizing without an expander ball, using dry lube inside the necks, using wet lube in the necks, not using any lube and to be honest, the only method that made a noticeable difference was NOT USING LUBE. Rounds that had no lube inside the necks were inconsistent in their seating and could be felt through the press. My take away from the tests was that I achieved more consistent seating with lube in the necks regardless of the sizing method.

So, my conclusions based on my testing and how I reload showed that sizing methods using FL and bushing dies (each type with and without expander balls) had little affect with the results on the target or my numbers on the chronograph.

I typically wipe my brass down, anneal, brush the inside of the necks, FL size (some with an expander ball, some without), trim if necessary, prime, dip the necks in Redding dry lube (graphite), drop powder and seat bullets.

 

[Hot Karl]

Spife7980 gave you the answer to your specific question but from my experiences, I'll analyze the problem from a different perspective. First, a few questions:
What brass are you using?
How do you clean your brass?
Do you brush/clean the inside of your necks after annealing?
Do you lube inside the necks BEFORE dropping powder and seating bullets?

I have found the above important because the quality of brass you are using is going to have a bearing on the consistency of your neck wall thicknesses. I use Lapua brass so my testing, listed below, was done with brass known for having consistent walls. How you clean your brass also has a bearing on neck tension as methods using stainless pins or ultra-sonic cleaners will get the inside of the necks extremely clean. This brings up using a dry lube on the inside of the necks before dropping powder and seating bullets. Also, if you use a vibrator or wiping method of cleaning, then the carbon left in the necks gets torched in the annealing process and should be brushed before using lube.

I've tested sizing using FL sizers with bushings (Redding Type "S") AND without bushings (Forster), with an expander ball, sizing and using a mandrel, sizing without an expander ball, using dry lube inside the necks, using wet lube in the necks, not using any lube and to be honest, the only method that made a noticeable difference was NOT USING LUBE. Rounds that had no lube inside the necks were inconsistent in their seating and could be felt through the press. My take away from the tests was that I achieved more consistent seating with lube in the necks regardless of the sizing method.

So, my conclusions based on my testing and how I reload showed that sizing methods using FL and bushing dies (each type with and without expander balls) had little affect with the results on the target or my numbers on the chronograph.

I typically wipe my brass down, anneal, brush the inside of the necks, FL size (some with an expander ball, some without), trim if necessary, prime, dip the necks in Redding dry lube (graphite), drop powder and seat bullets.

So my here’s What I have.
Ruag Brass
Cleaning process
-Deprime
-Wash with fine steel (like ultra fine media) media 1/1.5 hours dish soap & lemi
-Anneal
-Lubricate -lanolin/iso
-Larry Willis belt size
-Redding FL Type S bushing die (no expander)
-Wash 3/4 hours (really get primer pockets)
-Imperial Dry neck lube
-mandrel (I massage the neck of the case back and forth)
-prime
-powder
-seat

I guess one of my main questions is how you determine the bushing size to mandrel. Because I want.002-.003 tension. Bullet being .308 I want inside diameter to be .305/.306 so would I size neck down to .304 or .305 then use the appropriate mandrel one size up? That makes sense to me? But To determine the bushing size of OD to mandrel which is ID I am Curious if it’ I’d just do The normal math subtract .002-.003 from neck thicknesses x2+.308 ?

 

[Hot Karl]

I've experimented with my .308 cases in trying to get my case as uniform and true (true = neck runout less than .001). My experience with bushing dies is that the bushing induces additional runout on a case that's been fired. And and expander ball does the same. Those two thing together put way more runout on the neck than I wanted. Running a bushing die without the expander ball helps a lot, but then running an expander mandrel afterwards, doesn't help much to improve the runout after sizing with a bushing die. So, what I found that works really well for me is I use a Forster FL sizing die without the expander ball and run an expander mandrel afterwards, which give me very close to the same runout on the neck as it is right after firing (less the .001, typically ~ .0005).

I turn my necks also, but in comparing my turned necks to those that were not, where I've sized the cases as I like, I found doing so doesn't really make much difference in runout. The variances in neck thickness can give you a false runout measurement on the neck when the expander mandrel moves the variances in neck thickness to the outside where runout is measured.

When the necks are not turned, a bushing die will move the variances in neck thickness to the inside, which can result in runout on the bullet that's not acceptable. But if you turn thee necks, then there's no (or very little) variance to be moved anywhere. But the bushing in a die still tens to induce some runout.

I've heard people claim they get good results with a bushing die (or at least acceptable results), but that just wasn't my experience with them.

So I am trying to get .002-.003 tension, simply because I want to be able to hunt with b the rounds I use (Berger 230g OTM). So to avoid risking a round from getting stuck, or moving on me, I want to be able to experiment with neck tension. I am not overly concerned with a stuck Bullets because I am loading between .040-.085 off the lands (experimenting against the typical .010 etc). From what I’ve gathered .002-.003 is Max and effective for these purposes. .001 has been rather inconsistent for me. I run Redding Type S bushing dies, and my prep work is pretty solid I’ve been told, listed in here. Now I did realize one mistake I was making was using the expander mandrel instead of the arbor. But even then some cases would seat really well, others would have almost none. So that leads me to believe that there’s inconsistencies in my necks. Last neck turner I used was a Hornady, and that very well could have been the issue, but my xxi century comes in later next week, so that problem is solved, it is was the problem. Neck tension has just been the skill I have not been able to master yet and is the largest culprit I believe in my process that’s having impact on accuracy. I also just purchased a set of their .0005 mandrels.

 

[straightshooter1]

I guess one of my main questions is how you determine the bushing size to mandrel. Because I want.002-.003 tension. Bullet being .308 I want inside diameter to be .305/.306 so would I size neck down to .304 or .305 then use the appropriate mandrel one size up? That makes sense to me? But To determine the bushing size of OD to mandrel which is ID I am Curious if it’ I’d just do The normal math subtract .002-.003 from neck thicknesses x2+.308 ?

Always have to allow for some spring back. So, you'll want to bring the neck down to a size that the mandrel can do some work to bring it to the proper dimension to give you your neck tension. For figuring out the proper sized bushing, you'll first need to know the thickness of the neck wall.

Example:
Neck wall is .014 multiply that by 2= .028 Bullet diameter is .308 (in my case) So, .308 + .028 = .336 for the outside diameter with -0- neck tension. I want .002 neck tension, I subtract .002 from .336 = .334. I'll want an expander mandrel that give me this .334 (accounting for a little spring back - like .0005). Expander mandrel then has to be .334 -.028 - .0005 = .3055. As for a bushing size before using an expander mandrel, I'll want to have the neck drawn down to ~ .002 below what I want to neck tension to be. Therefore, the .334 is where I'll get my .002 neck tension, so I'll want a .3315 busing which will make the inside diameter of the neck .304 (that's assuming ~.0005 spring back with an inside diameter below that of the expander mandrel).

 

[Hot Karl]

Always have to allow for some spring back. So, you'll want to bring the neck down to a size that the mandrel can do some work to bring it to the proper dimension to give you your neck tension. For figuring out the proper sized bushing, you'll first need to know the thickness of the neck wall.

Example:
Neck wall is .014 multiply that by 2= .028 Bullet diameter is .308 (in my case) So, .308 + .028 = .336 for the outside diameter with -0- neck tension. I want .002 neck tension, I subtract .002 from .336 = .334. I'll want an expander mandrel that give me this .334 (accounting for a little spring back - like .0005). Expander mandrel then has to be .334 -.028 - .0005 = .3055. As for a bushing size before using an expander mandrel, I'll want to have the neck drawn down to ~ .002 below what I want to neck tension to be. Therefore, the .334 is where I'll get my .002 neck tension, so I'll want a .3315 busing which will make the inside diameter of the neck .304 (that's assuming ~.0005 spring back with an inside diameter below that of the expander mandrel).

Fuckin MINT! Thanks man. Really appreciate it.