Pros and Cons of expander balls

[Maggot]

Hi Maggot Its a difficult one; bushes will give an exact profile to the outside of the case, while a mandrel/ball will give a more exact profile to the inside of the case - the latter probably being the most important. You are right that bushes give a lot more options in sizing the neck, but only take account of differences in neck thickness, where the mandrel is directly related to the bullet dimension i.e. 0.001" or 0.002" smaller and I can see it provides more of a constant in neck tension than using different bushings to accommodate different dimensions of brass at the neck - particularly with different makes of brass. A mandrel will ensure the same neck tension whatever the make of brass or thickness at the neck.

Its always made more sense to me to size the inside of the case neck rather than the outside, although I have mostly used the bushing method. I now intend changing to inside sizing with mandrels and give it a go. I have to say I am convinced, but time will tell. I neck size the full length so using a mandrel will not change this. It'll be interesting to see what effects it has on the life of the brass. Presumably if you only resize the neck with a bushing to 80% the mandrel will only open up that much, because the un-sized portion will be bigger than the mandrel.

Hmmm....I was thinking about this at work, it does make sense.

I guess it makes more sense if you than neck turn to get the necks 100% uniform, but how long does the effect of neck turning last before flow thickens it up?

Very interesting and logical if you think about it.

Even if you don't do the full length it should not matter as you will only open that narrower part up again.

Although it all depends on the quality and uniformity of the neck in question....

I would not actually mind extra processes if they have a point, I guess if you got your neck bush and mandrel well matched it could be a recipe for good consistent neck tension.

Then of course you have to worry about annealing.....oh mother!!

Ovenpaa....you may get a phone call.....

[ColinR]

Whoever said reloading would be easy, but that's what makes it fun and swirls the grey matter around..........!!!

[Matt]

Call me old mr thicky....

I have seen folk using mandrels, but have tended to just use a bush without an expander ball.

Why have different sized bushes if you then shove a standard single sized mandrel down the inside of the case?

Moreover, how do you then partially re-size the necks? I only do 75-80% of the neck length.

Oh ok then.... Old mr thicky tongueout

[Maggot]

Call me old mr thicky....

I have seen folk using mandrels, but have tended to just use a bush without an expander ball.

Why have different sized bushes if you then shove a standard single sized mandrel down the inside of the case?

Moreover, how do you then partially re-size the necks? I only do 75-80% of the neck length.

Oh ok then.... Old mr thicky tongueout

Run Forest..... zzzzom

[Matt]

[Maggot]

Thanks rox that's good enough reason to go with the carbide mandrel. I'll order direct from Sinclair and have it shipped to my niece in US for onward despatch. I'll probably order both mandrels so I have the choice.

Hmmm

Interesting. The mandrel method does make sense, a well known F/TR shot I know does this, now I know why.

I ordered the sinclair unit and it arrived next day with the carbide (neck turning mandrel) rather than the expanding one.

This slid nicely into a prepped case, so I guess if I was to use it I would need to neck the brass down a tad more. Ovenpaa has very kindly loaned me the larger .307 item to try out.

I know that my tensions are less than factory, but not withstanding annealing etc, as long as the tension is a uniform as it can be, does it matter if I tighten it up a bit?

I guess peak pressures will go up a bit.

I only use Lapua Palma, so have not neck turned anything, but I cannot help wondering if it may help in a limited way.

That said, the whole lot has to be the same accross batches or you end up using different bushes for different batches, and I only load in 50 round batches.

I feel a bit of testing coming on...again!!!!

[ColinR]

Hi Maggot seems like me you have invested and become a believer too. I bought the die and both mandrels from Sinclair in US via my niece who lives there and they are winging their way here right now. The lot cost the equivalent of £55.00 including carriage in US. May I ask where you bought from, presumably in UK, and how much you paid? I tried to find someone in UK with stock but didn't have much luck.