Whidden FLS Bushing Die used with expanding mandrel?

[260AckImp]

Hello everyone

Just after some information regarding the use of a Expanding Mandrel after a FLS Bushing die. I currently have a custom die being made at Whidden gun works and Im trying to understand the concept of the use of Expanding Mandrels after using a FLS Bushing die to help concentricity.

I dont need to turn necks as I have a no turn chamber so really my question is am I best off running all my brass through a expander mandrel before seating bullets? I will be using bushings in the FLS die that will give me 2 thou neck tension and with the expander ball removed.

Apologies in advance if its a dumb question as Im still green about all this stuff.
Thanks for any information

 

[Dusty Stevens]

You dont need the expander set. They always try to push it and it will come with one- just remove that and keep it incase you need to straighten some off-round case necks. Just use the knurled decapping pin keeper. If you need to fine tune your expansion, do it in another step with a dedicated expander mandrel die. I suggest the porter precision mandrel die. As always you should turn your necks to about 95%+ to clean them up for best results. Doesnt matter that you have a bigger neck size

 

[MikeMcCasland]

I don't think expander mandrels are required for what you're doing, however they're very nice to have, and I still use them.

I doubt they'll help you much on concentricity, but if you're not turning your brass, in theory running it through the mandrel prior to seating will push any high-spots/inconsistencies to the outside of the neck, and make your interference fit more consistent.

It's been my experience that after several firings on brass, and even annealing every time, you'll get inconsistent neck tension if you keep using the same size bushing (i.e. inconsistent springback). When I've run into this, I've always dropped a bushing in size, and relied on the mandrel to open them back up; bullet seating has felt much more consistent doing this.

Lastly, I'll occasionally dent a case mouth on ejection, or by dropping the brass. Sometimes this can be fixed by just running it up into a sizing die, but every once in a while it won't fully iron it back out; mandrels are nice for this.

I don't think you need the whole set in .0005 increments though. I'd just grab one that's caliber minus .001, maybe +/- .0005 in either direction of that number (so for example on a .30 cal a .3075, .307. .3065.

Whatever mandrel you get, make sure you measure it to make sure it's actually the size it's marked.

Pin gauges are another alternative to mandrels that might be worth researching; they basically do the same thing.

My 2c.

 

[Uncle Ed]

The Redding bushing FAQ tells you if your neck thickness varies .002 or more to reduce the deck diameter an additional .002 for a total of .004 reduction and use the dies expander. Meaning use the expander to push the neck thickness variations to the outside of the case neck.

Also Whidden sells expander kits with five expanders from bullet diameter to .004 under bullet diameter.

Bottom line, using a expander of any type is not the end of the world as many people claim. And if you do not turn your necks you still need the expander to push the neck irregularities to the outside of the neck. And if you do not use a expander then you are using your bullet to do the same thing and this can induce neck runout.

Watch the video below, a standard non-bushing Forster full length has less runout than a Redding bushing die. They recommend to have the neck honed .004 smaller than a loaded round. And the same .004 recommendation for neck diameter reduction that Redding makes with their bushing dies when the necks are not turned.

 

[Arky]

+ 1 to what Dusty said, I have found that is the easyest way to get perfect neck tension.

 

[260AckImp]

Thanks everyone for the information, I have been finding that when im seating 142 Sierra Matchkings with a K&M arbor press and Wilson Inline Micrometer seater that I get CBTO variations up to 0.002"
Could that be caused by neck thickness variations or more likely to be the amount of variation of the ogive in a box of Sierra 142's?

 

[MikeMcCasland]

More likely the Sierra's.

 

[260AckImp]

No worries

Something like having a seating depth variation of 0.002" cause much difference? Im not sure if I should be adjusting seating die every bullet or not

 

[MikeMcCasland]

No worries

Something like having a seating depth variation of 0.002" cause much difference? Im not sure if I should be adjusting seating die every bullet or not

With a 142 SMK? I doubt you'll see any difference; those bullets are very forgiving on seating depth.

 

[260AckImp]

With a 142 SMK? I doubt you'll see any difference; those bullets are very forgiving on seating depth.

Thanks for the heads up!

 

[D-4297]

Hey Fullbore . I went through the process of "Turning" necks , and all I got was a 8-10 point drop in my Midrange scores with a "No-Turn" chambered rifle . Neck turning is not the be-all , end-all as some claim for all rifles . Guess it required if your a BR syncophant . But now ; I've got about $100.00 bucks worth of nice K&M stuff in my cabinet . I use a Whidden F/L Bushing die and also do the expander mandrel Die afterwards . I anneal after every firing , too . What worked best for me was to pay attention to the I.D. of the case . Find a bushing that will take your I.D. down .003 below your bullet diameter , and a expander that will open the case back up to .001 - .0015 below your bullet diameter . That isn't over-stressing your brass if you are annealing , and you should see a improvement in accuracy . And the variance in seating depth is not any issue . A good base-line for any reloader should be +/- .001 from your desired seating depth .

 

[mikecr]

There is a reason pretty much all sizing dies come with expansion.
You should look at it as 'pre-seating expansion'. It's doing what you don't need bullets doing.
And it happens that mandrels do it very well.

Also, brass relaxes over time opposite of last energy added. If your last action with necks was down sizing, then outward spring back continues, reducing tension over time. If your last action was expansion, then spring back would continue inward(where allowed). While unable to relax inward (due to seated bullets), tension is at least maintained.
If you understand this much then you should recognize it as one of the reasons FL sizing of necks is a bad action. There are other reasons too.

Nothing wrong with Sinclair gen II expander body, and Sinclair or PMA or 21st Century mandrels.
It would be ideal to find & use a carbide mandrel at cal (or least under cal available).