Mandrels

[maltbuck]

I am about to go down the route of removing my expanders from my sizing dies, and simply use a mandrel to size the internal neck diameter. Could someone please clarify the difference/when to use an expanding mandrel vs a turning mandrel, as I am not sure which to get. Or is as simple as the clue is in the name, I.e. I should get the expander mandrel, because I am not intending to neck turn for the moment.

 

Also in the process of brass prep, should I use my expanding mandrel before or after using my FL redding bushing die.

 

Thank you in advance,

MB.

[garyw]

MB- the expander mandrels i use -k+m -are larger then the neck turner mandrel only by a few thou.i do use a expander mandrel for my.284 as i dont have a bushing die for that calibre.

[The Gun Pimp]

Usually, you will find that a mandrel of calibre size will work - i.e 0.308 diameter if loading 308. There is always a bit of spring-back in the brass which gives you enough neck tension - but it will be less than a die will normally give you.

 

Normally you would full-length size with the expander ball removed then run 'em through the mandrel. Don't forget a very light lube in the neck.

[Toby]

So what you are saying is that this is another option.

Shoulder bump 1-2 thou in FL die with expander removed and then use mandrel to set neck tension?

[gunner]

Why would you remove the expander ? Thats the whole point of a FL sizing die isn't it ? If your wanting to use your FL die JUST for shoulder bump then you will probably be better off with a type S bushing die that does the neck only , then you can set tention to disired bushing size ! If you use an expander , you mite be sizing the necks out of tru if there just sat in the shell holder . Then that would cause bullet run out. That sound right ? Cheers

[gbal]

MB,if you have not looked at Accurate Shooter "Expander mandrels and neck tension"(google it),it's short but quite informative,and reinforces Gunner's(and Vince's) point that the expander ball works brass more- squeezes neck on down,ball expands neck on up-often leads to more bullet run out (concentricity lower).

There are other technical articles too in the AS site-well worth a browse,if in pursuit of achievable improvements-though don't expect miracles-even basic dies etc get quite close.Brass should last a bit longer,if worked less.

gbal

[The Gun Pimp]

The 'mandrel' system is used by a lot of shooters who are concerned with getting the most from their handloads. Factory dies are not all the same - some give better results than others.

 

If I was attempting to load say a very accurate 308 round, my first step would be to full-length size using a Forster die with the expander-ball removed, then up-size the necks with a mandrel and finally, seat the bullet with a Wilson seater die. As an alternative to the Wilson hand-die, the Forster benchrest seater die gives excellent results.

[Redshift]

Another alternative is to buy a fl die from forster and get them to hone the neck to your desired size before sending it to you, that way you are not over working the brass by reducing it too much before expanding it, they will hone it to a 1/2 thou so you should be able to get the exact size you require.

Last time I had it done it cost me the princely sum of £40.00 + p&p ( which was very low)

If you get 3 done at the same time all with 1/2 thou different necks you should have all bases covered regarding bullet/ neck tension, as a plus point forster are very nice people to deal with.

 

Redshift

[maltbuck]

Many thanks for all the replies, things are now clearer and confirms the way I intend to go - at least for the time being. Until of course I hit another flier problem with the fickle art of reloading!

Interesting to see people promoting Forster dies in particular.

 

A Happy New Year to all!

 

The one good thing about working NYE, is that you get to watch the suffering the next morning, - wife plus guests in our household!!

[DaveT]

Gents

 

Following through this thread confirms my long-held understanding that an expander mandrel should leave enough neck tension to retain a bullet satisfactorily....but...

 

I have used the K & M mandrels in 260 Rem (6.5mm) and 6mm with good results but when using a new 308 mandrel the other day to ease excessive neck tension on virgin Lapua brass the result was that the bullet slid right through the case with very little hand pressure !

 

Suitably bewildered I went on to use a neck sizing bushing die to correct matters.

 

I measured the mandrel and it shows .308 to .3085 depending on my level of dexterity with the calipers.

 

I would have expected enough spring-back after expansion to give me .001" or more of NT but clearly didn't get that result in this case.

 

I am thinking that either the brass is not exhibiting the expected spring-back (batch problem?) or the mandrel actually IS that little bit over-sized OR I simply have misunderstood their usage all these years!

 

Any thoughts or experiences very much appreciated.

[The Gun Pimp]

It might be an up-size mandrel - so that the brass will go on a neck-turner mandrel.

 

You could try running it down in an electric drill using emery paper (assuming you don't have a lathe). It will take forever to take a thou. or two off but you will!

[DaveT]

Vince

 

It may have been falsely packaged but is supposed to be an expander and not a neck-turning mandrel.

 

I wonder if anyone can confirm what their own 308 expander mandrel actually measures as I now distrust my own to do the job reliably?

[Swarovski1]

Sorry chaps but this sounds alot of faffing around for nothing.is this really necessary, convince me or show me proof please

[The Gun Pimp]

Swarovski - It's the way a lot of us reload. You don't have to do it but it makes sense.

[onehole]

Only use a mandrel the once,,,to pre-prep the "new brass necks" for neck bushing down sufficient to hold the bullet........Neck turning mandrel has to be first time more accurate to better fit the turner mandrel.......We are talking about new brass here guys or am I missing something.....O

[Brillo]

MB,if you have not looked at Accurate Shooter "Expander mandrels and neck tension"(google it),it's short but quite informative,and reinforces Gunner's(and Vince's) point that the expander ball works brass more- squeezes neck on down,ball expands neck on up-often leads to more bullet run out (concentricity lower).

There are other technical articles too in the AS site-well worth a browse,if in pursuit of achievable improvements-though don't expect miracles-even basic dies etc get quite close.Brass should last a bit longer,if worked less.

gbal

 

I've just read the article mentioned. Where can I get that mandrel and mandrel body?

[Swarovski1]

Swarovski - It's the way a lot of us reload. You don't have to do it but it makes sense.

hi GP.you must of seen some of my recent photos of grouping.i mite be wrong but I can't see I need to do this procedure.my 308 shoots equally aswell.maybe your way you find the magic load with less development and very consistant.you have been top man in GB so you must be doing everything right.ive certainly learnt alot off ukv since joining.there does seem an awful lot of members that don't participate with their thoughts and opinions.

[gbal]

Brillo....the Accurate Shooter article has a highlighted link....

 

"The expander mandrels from SINCLAIR INTERNATIONAL and K&M....."

 

I don't know all the UK distributors for Sinclair catalog stuff,bt Spud or Reloading Solutions are likely suppliers....K&M might be best contacted directly...they do upmarket reloading gear...

no doubt other forum followers will know likely sources too....

Sinclair International catalog online too....but be carefull,temptation abounds therein.....

 

g

[Brillo]

Thanks gbal. I'll browse at my peril

[The Gun Pimp]

hi GP.you must of seen some of my recent photos of grouping.i mite be wrong but I can't see I need to do this procedure.my 308 shoots equally aswell.maybe your way you find the magic load with less development and very consistant.you have been top man in GB so you must be doing everything right.ive certainly learnt alot off ukv since joining.there does seem an awful lot of members that don't participate with their thoughts and opinions.

Swarovski - your short and long-range groups are impressive.

 

I remember - 20 odd years ago being pretty pleased with my groups with my 308 Steyr SSG - so much so that I took a trip to a UKBRA comp at Minsterley on weekend - and finished next to last!

 

I learned a thing or two - competitive shooting is different than plinking - be it F Class or benchrest - you have to get down and do it - there and then. Your group may not be tiny, your score may not be large - it's just got to be better than everybody else's on that particular day.

 

Swarovski - if I had a rifle that shot like yours, I'd be doing what I did 20 years ago and testing myself in competition. That's where it counts - not on the forums.

 

The 1000 yard season starts in April - you'll be very welcome to come and shoot with us at Diggle.

[palo]

Vince

 

It may have been falsely packaged but is supposed to be an expander and not a neck-turning mandrel.

 

I wonder if anyone can confirm what their own 308 expander mandrel actually measures as I now distrust my own to do the job reliably?

Dave

My sinclair 308 expander mandrel measures .307 inches.

[Swarovski1]

I agree GP 100 percent. I do need to compete.i am very competitive.my aim is always for the podium in our interclub comps.i like the banter too.everywhere seems so far away from where I live.bisley is a 100 miles each way.thats probaly the closest place.my 6.5 06 barrel must be nearing the best end of its life.a new barrel a nee start.thanks for your nice comments GP on my targets I posted.i am shooting this Sunday at 1000yds.looking forward to it.

[DaveT]

Dave

My sinclair 308 expander mandrel measures .307 inches.

That tends to infer that mine is over zed. ...thanks for info.

[DaveT]

Dave

My sinclair 308 expander mandrel measures .307 inches.

That tends to infer that mine is oversized. ...thanks for info.

[The Gun Pimp]

I agree GP 100 percent. I do need to compete.i am very competitive.my aim is always for the rostrum in our interclub comps.i like the banter too.everywhere seems so far away from where I live.bisley is a 100 miles each way.thats probaly the closest place.my 6.5 06 barrel must be nearing the best end of its life.a new barrel a nee start.thanks for your nice comments GP on my targets I posted.i am shooting this Sunday at 1000yds.looking forward to it.

Try one weekend with us a Diggle this summer. Travel up on the Saturday - have a meal meal and a beer with us and shoot 1000yd benchrest on Sunday. Tisme has done it a few times.