MANDREL DECISIONS

[ARlife4me]

i've never been this anal about reloading, but (or should i state butt ) on choosing a or multiple sizes? so, neck tension is more about id than od which 1 can't be w/o the other. all i've done is full size using a button in 1 process and has worked for the last 42 years for me. so you don't control tension with od numbers alone? looking for something new to try against what i've done for comparisons that could make an improvement in my decades of reloading is all. i'm sure i'll get the "don't change what's not broken" answers or similar, but looking to try/learn something different? plus similar threads are many rears old and always get remarks about "well this thread (as in posting on a 3-5 yo thread) is old". from what i've read on forums you take the fired brass and shrink it by .002-.003" of od neck numbers?

 

[MagnumManiac]

There are very good reasons to either use a mandrel or not.
If you find that your rifles do very well with the method you currently use, then a mandrel may not change anything.
If you have a real precision oriented method for sizing, you can finish size your necks to precise numbers in .0005" increments until you find the sweet spot. Hard to do with a sizing die.
Mandrel use will not take a 1MoA rifle and make into a .2MoA rifle.
If you think it's warranted, then it will not hurt anything.
I use them on my rifles that shoot .5MoA or less, but, I also turn necks on these and size differently, and seat differently.

Cheers.

 

[Tiny Tim]

I switched over to mandrels a few years ago. I find it gives me more control over my process. I will say that I believe the last step in sizing should always be an expansion move, whether by button or mandrel. I'm unsure if I can shoot better with this process, but I feel much better about it!

All that said, I'm seriously considering a Forster die for higher volume shooting. Those can be custom honed to minimize brass work hardening and the button is mounted high on the depriming stem to help with consistent alignment.

 

[Turpentine21]

How are you today! We're hot as blazes here. I have recently started with mandrels and bushings in 6.5-06 and 6mm Creedmore. The 6.5-06 with the bolt gun was easy. Lapua brass made it easier although I annealed and downsized from 30-06. Loaded, formed, and annealed again.
6mm Creed has been for a different cause. I needed more neck tension for the AR. I picked bushing size at .003 under but it was a bit tight and accuracy went south. I didn't want to buy a bushing as I prefer to expand a case slightly on the last step. That's in the hopes that imperfections move to the outside of the case wall. I found happiness at .0025 neck tension. Accurate consistent loads have been the results.
Observations. Neck wall thickness in your cases need to most definitely be uniform. Or turned to be uniform. Otherwise, your neck tension will be all over the place. Same with the Lee Collet die. I know that sounds like Captain Obvious.
Annealing seems to help and make the work much smoother.
Now what I don't know for sure is if running the mandrel thru to expand helps reduce imperfections or doughnuts inside the case mouth or not. It's possible and logical. But I'm wrong a lot according to a few. What I have gotten in both cases is very accurate and consistent ammo with low ES and SD. I like the finishing touch with the mandrel. There are those here that do know for sure though. Hopefully they will chime in.
All that said, if you are getting your goal for acceptable accuracy and consistency from one simple full length pass. I'd stick with what I've been doing. I like the way you're thinking though. There's always that nagging feeling that if you don't try it you may be missing something big. Sometimes that nagging feeling will just send us down another rabbit hole. I'm thinking about doing what Bugs Bunny did. Just staying in the rabbit hole and hanging my shingle topside!

 

[ARlife4me]

How are you today! We're hot as blazes here. I have recently started with mandrels and bushings in 6.5-06 and 6mm Creedmore. The 6.5-06 with the bolt gun was easy. Lapua brass made it easier although I annealed and downsized from 30-06. Loaded, formed, and annealed again.
6mm Creed has been for a different cause. I needed more neck tension for the AR. I picked bushing size at .003 under but it was a bit tight and accuracy went south. I didn't want to buy a bushing as I prefer to expand a case slightly. That's in the hopes that imperfections move to the outside of the case wall. I found happiness at .0025 under for my mandrel. Accurate consistent loads have been the results.
Observations. Neck wall thickness in your cases need to most definitely be uniform. Or turned to be uniform. Otherwise, your neck tension will be all over the place. Same with the Lee Collet die. I know that sounds like Captain Obvious.
Annealing seems to help and make the work much smoother.
Now what I don't know for sure is if running the mandrel thru to expand helps reduce imperfections or doughnuts inside the case mouth or not. It's possible and logical. But I'm wrong a lot according to a few. What I have gotten in both cases is very accurate and consistent ammo with low ES and SD. I like the finishing touch with the mandrel. There are those here that do know for sure though. Hopefully they will chime in.
All that said, if you are getting your goal for acceptable accuracy and consistency from one simple full length pass. I'd stick with what I've been doing. I like the way you're thinking though. There's always that nagging feeling that if you don't try it you may be missing something big. Sometimes that nagging feeling will just send us down another rabbit hole. I'm thinking about doing what Bugs Bunny did. Just staying in the rabbit hole and hanging my shingle topside!

I'm doubting so-so but hopefully by Tuesday I'll be in better shape after having a neck procedure on c3 thru c6 to take care of the 25 years of chronic pain. Temp wise it's been blazing pf mostly 100°+. I forgot about bushings and not using mandrels as that might be a better way to go?

 

[Turpentine21]

I'm doubting so-so but hopefully by Tuesday I'll be in better shape after having a neck procedure on c3 thru c6 to take care of the 25 years of chronic pain. Temp wise it's been blazing pf mostly 100°+. I forgot about bushings and not using mandrels as that might be a better way to go?

I had C6-7 done in 2002. That was from an old football injury. I have to be more careful with it as it's way past its expiration date. I've had lots of fusing done on the lower end. S2-T10 for burst fractures and compression fractures. The lower end seemed to hurt more and heal slower. But there was a lot of trauma and damage from my injury and from having to have all the hardware removed and replaced because screws had snapped. Then a re break and straighten where the bones had fused crooked. That took six operations to get straight over 3.5 years. My neck surgery wasn't bad. It took 6-8 months to get feeling back in my hand and fingers. The neck pain was gone when I woke up. But I didn't have 3 levels done like you have. Take it slow, you waited a long time to do it so let it heal!

I like the bushing system ok. My 6mm creed die is an LE Wilson FL bushing with no expander ball in the system by design. I do prefer to expand slightly on last step so I use the mandrel last. Especially with the AR and some of the neck damage that can occur.
With my 6.5-06 I have gotten away from a regular full length die and expander ball except for necking down new brass. I use a Forster bushing bump 25-06 die after that and will get around four firings before needing to resize the cases. Just because I like to stay close to fireformed size, I'll size the body with my Redding body die. Then like always it gets the bushing bump die for neck and final headspace, then the mandrel because I like to expand the neck slightly. It's a bit of an around the elbow system but remember the body die is only used every fourth firing. If I shot it a lot more I would revise the system possibly but it sure shoots well right now I hate to change it. I'd like to go up a bushing and skip the mandrel. There's just something about that step that gives me confidence.

 

[ARlife4me]

I had C6-7 done in 2002. That was from an old football injury. I have to be more careful with it as it's way past its expiration date. I've had lots of fusing done on the lower end. S2-T10 for burst fractures and compression fractures. The lower end seemed to hurt more and heal slower. But there was a lot of trauma and damage from my injury and from having to have all the hardware removed and replaced because screws had snapped. Then a re break and straighten where the bones had fused crooked. That took six operations to get straight over 3.5 years. My neck surgery wasn't bad. It took 6-8 months to get feeling back in my hand and fingers. The neck pain was gone when I woke up. But I didn't have 3 levels done like you have. Take it slow, you waited a long time to do it so let it heal!

I like the bushing system ok. My 6mm creed die is an LE Wilson FL bushing with no expander ball in the system by design. I do prefer to expand slightly on last step so I use the mandrel last. Especially with the AR and some of the neck damage that can occur.
With my 6.5-06 I have gotten away from a regular full length die and expander ball except for necking down new brass. I use a Forster bushing bump 25-06 die after that and will get around four firings before needing to resize the cases. Just because I like to stay close to fireformed size, I'll size the body with my Redding body die. Then like always it gets the bushing bump die for neck and final headspace, then the mandrel because I like to expand the neck slightly. It's a bit of an around the elbow system but remember the body die is only used every fourth firing. If I shot it a lot more I would revise the system possibly but it sure shoots well right now I hate to change it. I'd like to go up a bushing and skip the mandrel. There's just something about that step that gives me confidence.

MAN, THAT WAS LOTS OF WORK ON YOUR END FOR REPAIRS! 11 years ago i has 4 fusions done in the front of my neck where my throat was pulled out of the way for it. dr said me voice box was really big. what'll be done mon and tue is a rfa (radio frequency ablation) where they burn/singe the nerves to keep the pain signals from reaching the brain. supposedly it can repair itself in 6 months to 6 years? a person on another forum had this done in the "L" section but only lasted 3.5 months on part of it and 5 months for the longest. so much for 6months to 6 years. if it works at all and gives me a month i'll be appreciative, but hope it last longer and not have to repeat it in a short time. my injuries was from 2 car accidents where i almost went thru the windshield on 1 and went upside down (didn't roll) in a convertible (soft top was on) w/o a seatbelt. not wearing the seatbelt saved my live as the driver's side was layed flat/flattened.


would a bushing be better than the mandrel?

 

[Mikecr]

so you don't control tension with od numbers alone?

What you're referring to is an implied interference fit, which goes to zero, when you up-size with bullet seating.
That's not what tension is.
Tension is a force, and forces are not displacements.

Consider a neck with a bullet seated in it. What grips (tries to squeeze) the bullet?
You might have noticed at some point that pulling a seated bullet leaves the neck sprung back to ~1/2thou under cal, and not whatever your sized interference was. So the force that gripped that bullet existed in only that ~1/2thou of springback.
That springback force (hoop force in this case) was applied to an area of bullet bearing, to provide some amount of total grip.

We know springback force is tied to brass hardness, and thickness at a given hardness.
Aside from that, what is squeezing your seated bullet?
Answer: the AREA that springback force is applied.

So if you can set your neck brass hardness, and thickness, to consistency (at any tested best values), how can you adjust neck grip/tension?
Answer: AREA applied
Tension is easiest adjusted (IMO) through neck sizing LENGTH.
10 PSI springback against .25" bullet bearing length = 2.5 lbf tension
Against .125 bearing = 1.25 lbf tension

Then what about interference?
Your brass springback represents it's elasticity. Anything beyond the ~1/2thou springback in this case is yielding(sizing). And with that, the brass can't fully recover, but accepts your sizing. During yielding, tension increases from far less -all the way to loss. So there is that, but there is bad, and nothing 'good' with all that change to brass.
In contrast, you could size necks to accept bullets with 1/2thou interference.
Then, there is no upsizing on seating. Just desired tension provided by full springback for a chosen bearing length, with way less working of brass.

If you want to tweak neck tension, maybe just to see what effect it provides, you might try adjusting neck sizing length.
Next time you load develop, you might begin with lower interference, and half a sized neck.
Assume that excess brass sizing is not the best approach, and see how that works.

 

[Nomosendero]

I bought mandrels for several calibers, but I have not seen any available for .375 cal.
Does anyone know if one is available?

 

[gunaddict]

bought mandrels for several calibers, but I have not seen any available for .375 cal.
Does anyone know if one is available?

21st Century Innovation has .375 caliber mandrels. I recently asked them.

 

[ntsqd]

The Porter Precision mandrel system should have no trouble with a ~.375 mandrel as it uses gauge pins for the mandrels and machine tool collets to hold them.

Brass work hardens as it is formed or re-formed. If the final .0005" of bullet to case mouth interference fit is all that matters then expanding to .003" under vs. expanding to .0025" under shouldn't matter. Except that I've seen it posted that it has mattered, so I think that there's something going on there that I don't fully understand. I suspect that the amount of work hardening in the neck is important to how much of a grip the neck has on the bullet. Maybe not the actual grip that each case has, but in how consistent that grip is from one case to the next. Moving the brass just 'that' far improves the case to case consistency. The problem that I see with this line of thought is that there should be some lower threshold that you need to cross, but no upper limit as far as case to case consistency is concerned - you're just working the brass more than is needed. From observation there does seem to be an upper limit, and that's the part that I'm failing to understand. That the metal's hardness with regard to cold-work is a non-linear relationship is what I'd expect. What I don't know is the shape of that curve.

 

[the bullet man]

go to the short action customs site and use the calculator. it will tell you what bushing and mandrel to use based on the info you provide. https://shortactioncustoms.com/product/300-winchester-magnum-neck-shoulder-bushings/

 

[Turpentine21]

What you're referring to is an implied interference fit, which goes to zero, when you up-size with bullet seating.
That's not what tension is.
Tension is a force, and forces are not displacements.

Consider a neck with a bullet seated in it. What grips (tries to squeeze) the bullet?
You might have noticed at some point that pulling a seated bullet leaves the neck sprung back to ~1/2thou under cal, and not whatever your sized interference was. So the force that gripped that bullet existed in only that ~1/2thou of springback.
That springback force (hoop force in this case) was applied to an area of bullet bearing, to provide some amount of total grip.

We know springback force is tied to brass hardness, and thickness at a given hardness.
Aside from that, what is squeezing your seated bullet?
Answer: the AREA that springback force is applied.

So if you can set your neck brass hardness, and thickness, to consistency (at any tested best values), how can you adjust neck grip/tension?
Answer: AREA applied
Tension is easiest adjusted (IMO) through neck sizing LENGTH.
10 PSI springback against .25" bullet bearing length = 2.5 lbf tension
Against .125 bearing = 1.25 lbf tension

Then what about interference?
Your brass springback represents it's elasticity. Anything beyond the ~1/2thou springback in this case is yielding(sizing). And with that, the brass can't fully recover, but accepts your sizing. During yielding, tension increases from far less -all the way to loss. So there is that, but there is bad, and nothing 'good' with all that change to brass.
In contrast, you could size necks to accept bullets with 1/2thou interference.
Then, there is no upsizing on seating. Just desired tension provided by full springback for a chosen bearing length, with way less working of brass.

If you want to tweak neck tension, maybe just to see what effect it provides, you might try adjusting neck sizing length.
Next time you load develop, you might begin with lower interference, and half a sized neck.
Assume that excess brass sizing is not the best approach, and see how that works.

Informative! Thank you, Sir!

 

[Turpentine21]

The Porter Precision mandrel system should have no trouble with a ~.375 mandrel as it uses gauge pins for the mandrels and machine tool collets to hold them.

Brass work hardens as it is formed or re-formed. If the final .0005" of bullet to case mouth interference fit is all that matters then expanding to .003" under vs. expanding to .0025" under shouldn't matter. Except that I've seen it posted that it has mattered, so I think that there's something going on there that I don't fully understand. I suspect that the amount of work hardening in the neck is important to how much of a grip the neck has on the bullet. Maybe not the actual grip that each case has, but in how consistent that grip is from one case to the next. Moving the brass just 'that' far improves the case to case consistency. The problem that I see with this line of thought is that there should be some lower threshold that you need to cross, but no upper limit as far as case to case consistency is concerned - you're just working the brass more than is needed. From observation there does seem to be an upper limit, and that's the part that I'm failing to understand. That the metal's hardness with regard to cold-work is a non-linear relationship is what I'd expect. What I don't know is the shape of that curve.

Again very informative, Thank you, Sir