Neck tension

[Tim L]

I've just started loading my 6.5x284 using a bushing die and I found inserting the projectile to be hard. Like too hard.

Previously I've been FL sizing every firing and running an expander mandrel down the neck. This was producing consistent results, great concentricity and I am wondering why I got the bush?
I measured everything and it all falls in line but I'm having to force the projectile into the neck with way too much force. This being the case I ran a mandrel down the neck of a few and I'm back to a nice comfortable seating pressure but with no measurable difference in the unseated neck diameter. I'm about to retire the barrel so I'm really just posing this for interests sake, and maybe pick up some advice to take into the future.


Fired neck 0.296
Bushing die 0.292
Sized neck 0.291
Seated neck 0.293

Brass is unturned Lapua, fire formed, cleaned and prepped (deburred inside and out).

[RDavies]

Just checking if you are not cleaning the inside of your necks and your FLS die doesn't have the expander in it does it?
If not the die expander wont be scraping the carbon/powder fouling off the inside of the neck.
Since having the powder fouling in the neck appears to increase friction, I use a bushing .001" bigger on cases which have been fired, which keeps the neck tension the same.

[AlanF]

I've just started loading my 6.5x284 using a bushing die and I found inserting the projectile to be hard. Like too hard.

Previously I've been FL sizing every firing and running an expander mandrel down the neck. This was producing consistent results, great concentricity and I am wondering why I got the bush?
I measured everything and it all falls in line but I'm having to force the projectile into the neck with way too much force. This being the case I ran a mandrel down the neck of a few and I'm back to a nice comfortable seating pressure but with no measurable difference in the unseated neck diameter. I'm about to retire the barrel so I'm really just posing this for interests sake, and maybe pick up some advice to take into the future.


Fired neck 0.296
Bushing die 0.292
Sized neck 0.291
Seated neck 0.293

Brass is unturned Lapua, fire formed, cleaned and prepped (deburred inside and out).

All the measurements look reasonable. Exactly how did you clean the inside of the necks? If it was ultrasonically then people have reported problems with too much friction when seating.

[Tim L]

Yep OK, it could well be residual carbon in the neck. I dry tumble, they look clean, but the inside isn't anywhere near as shinny as the outside
I used the mandrel dry, so no contaminants offering lubrication, but it could be offering a bit of a cleanup on the inside. I'll take a closer look this arvo.

[RDavies]

How about just sizing some with a .001" bigger bushing? See if neck tension feels right. I like leaving inside the necks dirty, less chance of bullets sticking in the case necks if you leave them loaded for extended periods.

[williada]

How about just sizing some with a .001" bigger button? See if neck tension feels right. I like leaking inside the necks dirty, less chance of bullets sticking in the case necks if you leave them loaded for extended periods.

Rod that is a great typo. I pissed myself laughing.

Tim, there is the possibility that the bushing does not measure what is says, if this is the first time you have used it. The only way to check is with a pin gauge. Sometimes once fired cases really shrink and its a composition hardness issue with the brass and a hot load. If the latter is the case they need torching.

[aaronraad]

I assume the projectiles are all from the same batch. Worth running the mic over the shank to make sure max OD of the shank hasn't changed significantly from the previous batch.

[Brad Y]

Agree with the comment regarding the bushing size. I actually use a wilson 310 in my 7mm and with un turned brass This should give 3 thou tension, but a 311 I could move the projectile by hand. Using a wilson seater that has plenty of feel, I dont believe I have 3 thou tension either. But instead of worrying about numbers and buying expensive micrometers to justify everything correctly, I found it was just easier to get another bushing that worked.

[Tim L]

Buttons?

Are we talking expander ball here? I took that off. I didn't see the point of spending $50 on a precision bush that sizes the outside of the neck then pulling a bit of stuff back through the neck expanding it again.

I used my mandrel when FL sizing because I needed a solution to having necks that were way too small from the FL die. The expander mandrel felt right over the turning mandrel.
I'll clean a few necks with a brush and see if that has an effect on seating.

Projectiles are from the same box

[BATattack]

Measure the inside diameter of the bushing with a ball end micrometer. It's probably smaller than its supposed to be if you have to use significant force to seat.

[RDavies]

I assume the projectiles are all from the same batch. Worth running the mic over the shank to make sure max OD of the shank hasn't changed significantly from the previous batch.

You certainly have that one right Aaron, some of the popular bullets out there have been all over the place with diameters lately between each lot.

[RDavies]

How about just sizing some with a .001" bigger bushing? See if neck tension feels right. I like leaving inside the necks dirty, less chance of bullets sticking in the case necks if you leave them loaded for extended periods.

Rod that is a great typo. I pissed myself laughing.

Tim, there is the possibility that the button does not measure what is says, if this is the first time you have used it. The only way to check is with a pin gauge. Sometimes once fired cases really shrink and its a composition hardness issue with the brass and a hot load. If the latter is the case they need torching.

Oops, edited it now.

You are right about bushings not measuring up. With my short mag, I have bushings which are supposedly .001" apart, but are in fact .0025" apart. To get the correct neck tension in this particular case I have to run a brush once inside each case neck.
Everything else I leave inside the necks alone.

[williada]

Tim, I meant to say bushing. The “springback” base line of the brass is different with your two setups because you used the mandrel again and felt no difference from original setting. Then it is most likely the die bushing is probably undersized. Measurement will only tell. Brad's suggestion of trying different bushings is sensible if you do not have measuring equipment. Maybe someone can lend you some to try. Or maybe you could try a Lee collet die. Anyway, if the original setup works, stick with it.

In my case, I do not use a mandrel all the time, only when I am conditioning the cases after annealing. I used to use a collet die, but now I am using thinner walled necks on a different chamber and I go with just the bushing and have no run out problems. But beware the mandrel without plenty of lube can harden those necks and vary the case “springback” memory if overused. Its all fun Tim. David.

I'm still laughing Rod.

[Tim L]

Thanks all,

I don't have a mic, but I know a man who does so I'll check it.

[Roy cobb]

Iam only new to reloading so how much neck tension do you need what is too much or not enough and how do you tell, looking for you help ( Hi there R Davies )