Forster full length sizing die

[TommyD11730]

So, I aquired a full length size die (308 match) by Forster. First observation is its bumping back on avg 1.5 to 2 thousands. Neck tension measures 305 (vs the 308 my neck only die produces) and the runout looks good.

My only concern is how my rounds are going to shoot with the increased neck tension. Does anyone make mandrels I can swap in to adjust/tune the neck tension?

Thanks!

 

[AllenOne1]

You can send that die to Forster and have it honed out to a diameter of your choosing and then use a mandrel die to finish sizing. It does turn it into a two step process but works really well IMO.

 

[918v]

How are you measuring neck tension?

 

[TommyD11730]

How are you measuring neck tension?

MATCH GRADE - Case Mouth and Neck Tension Gage 224 / 308

Match Case mouth gauge or gage for determining neck tension of 223, 5.56, 308, 30/06, etc. Match grade.

ballistictools.com

 

[TommyD11730]

You can send that die to Forster and have it honed out to a diameter of your choosing and then use a mandrel die to finish sizing. It does turn it into a two step process but works really well IMO.

Do you have a favorite brand mandrel die I can research? I don't mind a 2 step process, I have a tendency to over complicate things.

 

[AllenOne1]

Do you have a favorite brand mandrel die I can research? I don't mind a 2 step process, I have a tendency to over complicate things.

I have the Sinclair one but there are couple of others as well. 21st Century, LE Wilson probably others. I think the Sinclair and 21st Century can use the same mandrels, but check it out before you jump on it.

 

[918v]

I like the Sinclair die as well. Apparently 21st Century makes expander mandrels in .0005” increments so that’s the best way to go.

 

[Cardboard Assassin]

I like the Sinclair die as well. Apparently 21st Century makes expander mandrels in .0005” increments so that’s the best way to go.

They only make them in plain old stainless though, no fancy black or titanium nitride.

 

[918v]

Not necessary if you use graphite to lube the necks prior to expanding.

 

[TommyD11730]

Can I ask how much spring back you guys are seeing?

 

[918v]

Depends on how soft the brass is

 

[CK1.0]

While there's no way I'd talk anyone down from using a dedicated FL die > dedicated Mandrel die...

Couple things: are you using the expander ball? And, do you anneal every firing?

The Forster FL dies probably have the least obnoxious expander ball design of almost anybody out there, pretty unobtrusive actually, doesn't try to rip the shoulder off on the way up like pretty much everyone else's. Their stock expander balls are supposed to be -.001 under bullet OD.
Unique to their design, supposedly they expand the neck while the case is still in the "bushing area" neck-zone. I've actually been meaning to check one out.

If you anneal every firing, that should give you a case mouth ID of .307. It's not the same as a true mandrel, but it's not bad for at least figuring out what's going on, and it's supposed to be .307" unless someone turned down or ordered a custom expander ball to drop in it before you took possession (Forester does custom expander balls too, or anyone can turn one down if they chuck one up in a drill and have a Scotch-brite pad kicking around). Theoretically, if one wanted ".002 neck tension" with zero guessing while working their brass the least, one could measure their brass neck thickness, order a custom honed die and an expander ball at -.002" under bullet OD and have their .002 neck tension setting.

I've found that on annealed brass, a cleverly designed "expander ball" actually works about as well as a dedicated mandrel die. I've been using a Mighty Armory lately, and while they call it a "mandrel" in their FL dies, it's really just a fancy expander too (just less of a ball).

The Mighty Armory's is a lot more rigid, so it probably deflects less and acts more like a mandrel than than the Forster, but the Forster does the same type of thing: expands without fucking the shoulder up. On malleable annealed brass, being less stiff may not be such a big deal anyways, some may actually prefer it (one man's deflection, is another man's "float" after all...). Also, since the Forster is supposedly doing the dirty while the neck is still in the upper die walls, it probably doesn't allow for the expander to pull the neck and shoulder as wonky.

Since you've got the Ballistic Tools gauges, I'm guessing you're annealing every time, and in that case, at least you've got something to try without ordering anything, just measure the expander ball OD, and if it's .307" like it's supposed to be and you are using the expander ball and getting a .305" neck ID, something else is up, thick brass maybe?..? Might need this: https://www.forsterproducts.com/product/oversize-e-z-out-die-expander-balls/

If you are not annealing every firing, then IMHO you are playing the "spring-back" guessing game. That's defiantly the hard way, trial and error that you'll have to repeat like Groundhog Day every time you get a new/different batch of brass going . I don't say that to be a dick, I just think discussing neck tension without mentioning annealing is dumb.

 

[marchboom]

While there's no way I'd talk anyone down from using a dedicated FL die > dedicated Mandrel die...

If you are not annealing every firing, then IMHO you are playing the "spring-back" guessing game. That's defiantly the hard way, trial and error that you'll have to repeat like Groundhog Day every time you get a new/different batch of brass going . I don't say that to be a dick, I just think discussing neck tension without mentioning annealing is dumb.

I agree 100%. Loading a round that has been fired once or twice will have a different neck tension than a case that has just been annealed. IMO neck tension is critical to obtaining consistent ES/SD readings and good groups. Since I have such a hard time keeping track of which groups of brass have been annealed, I just anneal every time I load. Just easier that way and I know that the brass will be the same each time.

 

[CK1.0]

I agree 100%. Loading a round that has been fired once or twice will have a different neck tension than a case that has just been annealed. IMO neck tension is critical to obtaining consistent ES/SD readings and good groups. Since I have such a hard time keeping track of which groups of brass have been annealed, I just anneal every time I load. Just easier that way and I know that the brass will be the same each time.

Yeah, I probably could've said it in fewer words, but I guess what I was trying to say is: repeatable neck tension is actually pretty easy to figure out if you anneal every firing... if you don't: not so much.

On non-annealed brass, IMHO following the FL die with a dedicated mandrel is pretty much mandatory, on annealed brass it seems like a cleverly designed expander is all that's needed to do the trick.

Either/both will help push imperfections to the outside of the necks so bullets have a happier place to be seated, which IMO is really a huge part of the benefit one gets from using a mandrel/expander (maybe more so than what it does for helping one set neck tension).

Found this:

https://www.forsterproducts.com/pdf/Custom_neck-honing_full-die_form.pdf

Has a chart that says the OP's die neck ID should be 0.327" in the neck/bushing area. So knowing that, plus knowing the expander ball's OD should be .0.307", the OP should be able to measure his brass thickness and then be able to make a call on how to move as far as adjusting his neck tension. Should also give an idea for a coming up with a good guess about the amount of spring-back, but again, there's really no reason to guess when one can just anneal every firing and not have to.

 

[TommyD11730]

While there's no way I'd talk anyone down from using a dedicated FL die > dedicated Mandrel die...

Couple things: are you using the expander ball? And, do you anneal every firing?

The Forster FL dies probably have the least obnoxious expander ball design of almost anybody out there, pretty unobtrusive actually, doesn't try to rip the shoulder off on the way up like pretty much everyone else's. Their stock expander balls are supposed to be -.001 under bullet OD.
Unique to their design, supposedly they expand the neck while the case is still in the "bushing area" neck-zone. I've actually been meaning to check one out.

If you anneal every firing, that should give you a case mouth ID of .307. It's not the same as a true mandrel, but it's not bad for at least figuring out what's going on, and it's supposed to be .307" unless someone turned down or ordered a custom expander ball to drop in it before you took possession (Forester does custom expander balls too, or anyone can turn one down if they chuck one up in a drill and have a Scotch-brite pad kicking around). Theoretically, if one wanted ".002 neck tension" with zero guessing while working their brass the least, one could measure their brass neck thickness, order a custom honed die and an expander ball at -.002" under bullet OD and have their .002 neck tension setting.

I've found that on annealed brass, a cleverly designed "expander ball" actually works about as well as a dedicated mandrel die. I've been using a Mighty Armory lately, and while they call it a "mandrel" in their FL dies, it's really just a fancy expander too (just less of a ball).

The Mighty Armory's is a lot more rigid, so it probably deflects less and acts more like a mandrel than than the Forster, but the Forster does the same type of thing: expands without fucking the shoulder up. On malleable annealed brass, being less stiff may not be such a big deal anyways, some may actually prefer it (one man's deflection, is another man's "float" after all...). Also, since the Forster is supposedly doing the dirty while the neck is still in the upper die walls, it probably doesn't allow for the expander to pull the neck and shoulder as wonky.

Since you've got the Ballistic Tools gauges, I'm guessing you're annealing every time, and in that case, at least you've got something to try without ordering anything, just measure the expander ball OD, and if it's .307" like it's supposed to be and you are using the expander ball and getting a .305" neck ID, something else is up, thick brass maybe?..? Might need this: https://www.forsterproducts.com/product/oversize-e-z-out-die-expander-balls/

If you are not annealing every firing, then IMHO you are playing the "spring-back" guessing game. That's defiantly the hard way, trial and error that you'll have to repeat like Groundhog Day every time you get a new/different batch of brass going . I don't say that to be a dick, I just think discussing neck tension without mentioning annealing is dumb.

I like the way you write. Reading comprehension was never my strong suit (my loss). However your post was very easy to read.
Ok.. yes, I anneal after every fireing. Also I anneal before I resize (as in the order of operation, deprime, clean, resize, clean, load).

Yes I used the stock (307 as measured) expander ball in the Forester die. I run the brass though the die 2x. Rotating 180 Degrees. Something I got in the habit of doing useing the Lee neck size collet die. Maybe it's not necessary on the Forester die and in fact doing me a diservice.
Thanks for the tips, so darn hot in this house now it's hard to think.