When to use an expander mandrel; is it even necessary?

[TheGerman]

What is the purpose of an expander die/expanding mandrel like Sinclair sells?

For everything I load I full length size and I am under the impression the FL die is the expander by default so I am confused as to what these dies/mandrels are for unless you are just going about this in a different way/method.

Right now I use Redding 'S' dies with the appropriate bushing in them. Is there any purpose in using this as prep or beforehand or is it just an extra step some people do, or do it only once for virgin brass?

 

[Tristian19]

I use Sinclair's Expander Mandrel prior to turning necks. Otherwise, I am not aware of any other uses/functions one would play.

At second thought, IF one is using a comp type die which does not have an expander ball and accidently dents a neck I can see using an expander to round neck, followed by resizing.

Otherwise, no other uses come to mind.

sent via Tapatalk

 

[scotharr]

I use a turning mandrel in place of the expander button on your decapping pin with the idea that it produces less runout than the expander button. In short, I have a Dillon 550 and the first station is a F/L sizing die with no decapping pin or expander button. The second station is a carbide turning mandrel. This mandrel is intended to create more even neck tension by expanding all the necks to precisely (as possible) the same size. Remember the bullet seats against the inside of the neck, so uniforming the inside of the neck produces most consistent neck tension and consistent neck tension is really important to accuracy. Many people have come to the conclusion that turning mandrels produce better brass runout than expander buttons, so that is the main reason you hear of them being used during normal reloading

 

[gstaylorg]

I use the Sinclair Gen II die and [oversized] expander mandrel for opening up the necks on virgin brass to give better neck tension consistency the first firing. I have no issues doing load development in prepped virgin brass as long as the necks are consistent. The other place I use the expander mandrel is on brass from some of my bolt guns with strong ejector springs. If you're not very careful and slow opening the bolt, there is a strong tendency to put a big flat spot on the case neck. A FL sizing die bushing will not completely remove the flat spot by itself. However, the expander mandrel will get rid of most of it; then the bushing can take care of the rest. For the price, I think the Gen II die and expander mandrels have been an extremely good purchase.

 

[dauntedfuture]

As already stated you can use the mandrel prior to neck turning. You can also use it to iron out necks on new brass. Alternatively, you can use the mandrel to uniformly expand and uniform the necks after you use a bushing die with the expander ball removed. The effect is that you are pushing the mandrel into the neck to expand it rather then pulling the ball up through a case. This also reduces the "sticking" when raising the press handle. Either way, you need an expander ball or mandrel or Lyman M-die if you are not neck turning your cases to maintain uniform neck tension. If you have good brass, you can sometimes get away without using the expander ball in non-neck turned cases.

 

[Milo 2.5]

I use Sinclair's Expander Mandrel prior to turning necks. Otherwise, I am not aware of any other uses/functions one would play.

At second thought, IF one is using a comp type die which does not have an expander ball and accidently dents a neck I can see using an expander to round neck, followed by resizing.

Otherwise, no other uses come to mind.

sent via Tapatalk

Some interesting thoughts given, but this guy summed it up for your application. If your bushing size is correct, running an expander mandrel or turning arbor into your case, it's the equivalent of pulling a bullet, you need to put the neck tension back on the case.

 

[rjacobs]

I run the setup from 21st Century Shooting on my prep heads on my Dillon 1050. The Dillon trim dies have a tight neck because they are cut with the same reamer as a FL size die, but obviously dont have an expander ball to pull back through the neck post sizing to set neck tension. So you have to do something to open the neck back up to set neck tension The mandrel dies do just this and the 21st Century mandrels are sized to set .002 neck tension.

In the case of using a full length die that has an expander ball, a mandrel die would be a waste of time and money IMO.

 

[Milo 2.5]

and the 21st Century mandrels are sized to set .002 neck tension.

Where did you get this little tidbit of information?

 

[rjacobs]

Where did you get this little tidbit of information?

I want to say it's on their website. .224 mandrel is sized .222.

If it wasn't there it may have been here somewhere or maybe Brian Enos.

 

[Milo 2.5]

I want to say it's on their website. .224 mandrel is sized .222.

If it wasn't there it may have been here somewhere or maybe Brian Enos.

I've never seen it in print, I have two 6.5 mandrels, 1-ss.1-tin, both measure .264, same as a bullet, I have 22, 6mm, 7mm, I can measure them also, the turning arbors are less in diameter, so the expander is allowing for some springback? I just think you're off base by saying you can set neck tension with a ex mandrel, there would have to be more factors involved.

 

[Milo 2.5]

Sorry rj, if the German set his neck tension with a bushing, then expands it, he's negated what he set out to do?

 

[rjacobs]

I've never seen it in print, I have two 6.5 mandrels, 1-ss.1-tin, both measure .264, same as a bullet, I have 22, 6mm, 7mm, I can measure them also, the turning arbors are less in diameter, so the expander is allowing for some springback? I just think you're off base by saying you can set neck tension with a ex mandrel, there would have to be more factors involved.

Like i said i can't remember where i read it. My brass starts out with very tight necks due to how i process it, so it works well for my setup.

Sorry rj, if the German set his neck tension with a bushing, then expands it, he's negated what he set out to do?

I agree. A bushing should be setup to set neck tension(and obviously shoulder bump) and not need any expanding, if it does, imo, the bushing isn't right. If he needs something to straighten necks due to dents from say a shell deflector, i would probably run the neck expander first to do that process.

 

[Milo 2.5]

I do agree, the ex mandrel is way better to straighten out dings, I've ruined a number of brass using the expander ball on them. Sorry if I came across as a Dick.

 

[rjacobs]

I do agree, the ex mandrel is way better to straighten out dings, I've ruined a number of brass using the expander ball on them. Sorry if I came across as a Dick.

Not at all. I think several people, including myself, started talking about using them differently than German asked about in the op. Different tools for different processes. They work well for my process since my sizing doesn't have an expander ball.

 

[Milo 2.5]

Not at all. I think several people, including myself, started talking about using them differently than German asked about in the op. Different tools for different processes. They work well for my process since my sizing doesn't have an expander ball.

Right on, agree diff purposes for tools. General consensus on SH is not to neck size, I have a neck sizing bushing die for every cartridge I load for, if nothing else just to facilitate neck dings, along with expander dies, and to put neck tension back after pulling bullets. And I'll neck size until I need to fl size, if a person isn't smart enough to test enough brass to figure if it's feasible, well?

Oh, I load on concrete, never saw a piece of brass hit the floor that wont land on the case mouth!

 

[SWRichmond]

I use a bushing die and have different bushings for different brass brands. In spite of this, and routinely annealing case necks, I still experience differences in force required to seat bullets. I have begun neck turning, and even in neck turned cases I feel a difference. Thus, I use an expander die on all cases (necks dry lubed) as part of case prep. All cases, every time.

 

[Sevo2300]

I run the setup from 21st Century Shooting on my prep heads on my Dillon 1050. The Dillon trim dies have a tight neck because they are cut with the same reamer as a FL size die, but obviously dont have an expander ball to pull back through the neck post sizing to set neck tension. So you have to do something to open the neck back up to set neck tension The mandrel dies do just this and the 21st Century mandrels are sized to set .002 neck tension.

In the case of using a full length die that has an expander ball, a mandrel die would be a waste of time and money IMO.

I use mine for the same purpose on the "prep" head of my 1050. For 308, the expander mandrel measures .3065 and the turning mandrel measures .3055. Another option would be the Lee collet neck die which has a mandrel diameter of around .305. I think that for neck turned brass, a properly sized bushing would be fine though.

 

[pmclaine]

I process on a S1050 with an Rapid Trim 1200. Ive been toying with the idea to get a mandrel in hopes I can avoid having to Chamfer/Debur after the RT1200 creates the squared sharp brass mouth.

As others have stated the size/trim die is tight. I don't mind the tension, it hasn't effected brass life but I really do hate the tedious job of debur and chamfer. Ive been told the mandrel dies "swage" back the trim so that bullets enter the case mouth without shaving jacket.

 

[rjacobs]

I process on a S1050 with an Rapid Trim 1200. Ive been toying with the idea to get a mandrel in hopes I can avoid having to Chamfer/Debur after the RT1200 creates the squared sharp brass mouth.

As others have stated the size/trim die is tight. I don't mind the tension, it hasn't effected brass life but I really do hate the tedious job of debur and chamfer. Ive been told the mandrel dies "swage" back the trim so that bullets enter the case mouth without shaving jacket.

I havent noticed that in mine. I still prefer to chamfer the case mouth with my hand tool, but my stainless tumbler takes care of all the deburring.

 

[pmclaine]

I havent noticed that in mine. I still prefer to chamfer the case mouth with my hand tool, but my stainless tumbler takes care of all the deburring.

Before I throw the brass into the vib to clean off lube I run it through the three stations of a Hornady 3 in 1. Inside chamfer, Outside debur and primer pocket cleaning. The inside chamfer is the only process Im really concerned about but as I have the brass in hand, and the other two tools are right there spinning away, I give the brass a three thousand count at each station.

 

[bbowles]

I have followed this thread closely cause I have a 6.5 CM std reamer being custom built and have been ordering reloading equipment for it. Have always used std FL dies but now I want to learn the finer points in LR shooting and reloading for concentricity. I have a Redding S Type FL die and competition seating die set. I planned on using this die without expander ball. After reading this thread and several others I am wondering if I should be using an expander mandrel, Lee Collet die, etc.?

My goal is to make sure functions in rifle (hence the FL sizing) everytime, runout is .001 or less on neck and bullet, and to have as few of steps as possible. I enjoy reloading but you can spend a TON of time if did everything there is to do. Due to time, I have decided I don't want to anneal or turn necks ( I would rather just throw away worn out cases and get more). UNLESS, that is required to get this type of runout.

My typical process is:
tumble hour or so, inspect cases
brush necks to clean
Sinclair Concentricity gage
FL size/decap on Redding Big Boss 2
tumble corn cob 1 hr
debur flash holes (only once on new cases)
uniform primer pockets
trim cases (just ordered Giraud, was using Sinclair Ultimate)
chamfer/debur/ brush case necks
sort cases by weight (new batch once only)
Sinclair Case Neck Sorter to check neck thickness variation (new batch once only)
Concentricity gage again to see how runout is after sizing
primer seating (RCBS handheld)
Powder charging (RCBS Chargemaster, love it!)
Sort bullets by ogive length
seat bullets (about .002 tension)
concentricity gage for bullet runout

I am not afraid of doing the work (fun for me to a point). I have not wanted to add steps like annealing or turning necks but don't know what steps should be done and what should be ignored as waste of time. My real question is best way to do sizing and setting neck tension which provides the least runout. I know there are a million ways to do all of this but am sure there is a better way than I have been doing. My runout using method above for my .223 has been about .002 avg using std FL dies. After reading many threads I have ran across many that think bushing dies are a waste and/or should be using Lee collet dies or using expander mandrel, etc. Very confusing. Thanks for the help and sorry for the length!

 

[mveto]

I use the expander mandrel only on new brass, I just used it on 400 pieces of new Lapua 308 brass. The new brass had a id of around .302-.304. I wanted to get a more uniform neck tension as well as work out some of the neck dings from the factory. When I reload I use a Lee collett die and only FL size when I need which is about every 3 firings.

 

[haroldwilson]

I use mine for the same purpose on the "prep" head of my 1050. For 308, the expander mandrel measures .3065 and the turning mandrel measures .3055. Another option would be the Lee collet neck die which has a mandrel diameter of around .305. I think that for neck turned brass, a properly sized bushing would be fine though.

Isn't the turning mandrel larger than the expander mandrel?

 

[BC 6.8]

Isn't the turning mandrel larger than the expander mandrel?

Harold - The expander mandrel is larger than the turning mandrel. The reason for this is after using the expander mandrel, the brass will spring back a little. The turning mandrel is about 1/1000" smaller in diameter to allow the brass to spring back and not be too tight when turning necks. If you get it too tight the brass will gall on the turning mandrel.

 

[haroldwilson]

Harold - The expander mandrel is larger than the turning mandrel. The reason for this is after using the expander mandrel, the brass will spring back a little. The turning mandrel is about 1/1000" smaller in diameter to allow the brass to spring back and not be too tight when turning necks. If you get it too tight the brass will gall on the turning mandrel.

Thanks. Makes perfect sense.

 

[SWRichmond]

It's not just about runout, it's also about neck tension. Afaik neck tension inconsistency is prevented by a) regular annealing and b) neck turning, in addition to neck brushing and, for me, use of an expander die. At 1000 yards it matters.