Mosin 91/30 Neck Expander Die

[JeffG]

Evening folks. I slugged the Mosin 91/30 tonight and it looks like I need about a .314 bullet. So far so good. What I'm having a little trouble finding is a neck expander die to get the bullet started without shaving. Anybody out there tried or using the Lee Universal Neck Expanding Die for this purpose?

[13Echo]

If you are going to seat a cast bullet that diameter I'd substitute an expander button for a .303 for the original button and use the Lee die to bell the case mouth enough to start the bullet or invest in a Lyman M die. Your die set is likely meant for jacketed bullets and the neck is expanded with them in mind. Seating a cast lead bullet will result in resizing the bullet as it is seated in the narrow neck hence the reason for the larger diameter expander button or using the Lyman M die which will properly expand the neck and also open the first part of the neck a bit larger to help get the bullet started.

Jerry Liles

[JeffG]

Thanks Jerry. That's the problem, Lyman isn't listing an M die, but that doesn't mean they may not have something special. I need to call them and check. The inside of the necks are .310 after sizing at present. I may get the universal expander (just found a picture of the parts makeup), seat a round then pull and mic it. I do prefer the M die as that is what I use on all my others. Take care

[462]

Contact member Buckshot. A fair price for a custom M-die expander plug of superb craftsmanship.

[Larry Gibson]

Lyman isn't offering their .31 cal M-die?

Larry Gibson

[Tackleberry41]

That $20 Lee expander die, but they should call it a flaring tool, is worth the investment. It doesnt expand like a conventional die, just puts a flare on the end like a pistol die will. I bought a .311 expander for my lee 7.62x54 die, havent really messed with it yet. But the lee 'expander' does work great on my 30-30. Just a hint of flare so it wont shave a cast bullet.

[gpidaho]

JeffG: If you are using the Lee die set be aware you might have to open up the center of the seating die to accommodate a .314 lead boolit. My Lee seating die would only take .311+ so I had to rework it a little to keep it from sticking a boolit or sizing it down. Newer dies may be different than mine. Just a heads up. GP

[462]

Lyman isn't offering their .31 cal M-die?

Larry Gibson

My 31 plug's first step measures .3100" and the second step .3142". For Jeff's .314" boolit, the 31 is too small.

I would want a custom plug made with the first step .312" and the second .315".

[Larry Gibson]

Uh, aren't we talking a MN here? It's not like any milsurp MN, not even the SAKO M39s or the Russian 91/28 snipers, are going to tell the difference in neck tension. I have already played that game as I have a Redding bushing die for the 7.62X54R and can get any amount of neck tension desired. I have tested neck tension using necks sized (inside diameter) from .310 to .3135 using .314 sized .311466s, 314299s, GB 314291s, GB 314041s and sized down 323470s. I could discern no accuracy difference with necks sized .310 - .313. I've use the .31 M-die since with complete satisfaction in any cartridge (54R, .303 Brit, 7.65 Argen, and 7.7 jap) taking a .311 - .314 sized cast bullet.

However, that being said I do like to not work the necks too much to increase case life so I usually use a bushing die for all those cartridges and size the necks to give .002 - .003 neck tension which is generally sufficient for feeding from the magazines in those rifles. With those the Lee case mouth expander die works quite well.

Larry Gibson

[tomme boy]

The main problem with Lee sizing dies is they are set up for 0.308" bullets. So they overwork the brass like crazy. So you have to order the 303 Brit expander mandrel to at least size for 0.310" If you complain enough they will send you one for free. You just have to keep pointing out that they are designed for 0.310" bullets not 0.308" bullets. I use RCBS for the Mosin. A FL and a neck die. They both come with 0.308" and 0.310" expanders. I also use a RCBS neck expander die with changeable expanders.

[Uncle Grinch]

I use my Lee expanding die on all my cast boolits. By just flaring the mouth you are typically guaranteeing a nice and tight neck tension, which help ignition, in my opinion.

[texassako]

The M die you want is listed for .303 Brit and 7.65 Arg by Lyman, or just get the 31R expander if you already have an M die body. You will still be working the brass a lot since the Lee FL die is going to size down the neck so far from where you want it no matter what expander is in it. I would use Larry's suggestion of Redding bushing die and Lee universal expander die.

[tomme boy]

The problem with using the Lee flair tool is the bullet is not going to seat straight. Seat some half way into the neck and tell me what you see. You are going to see a few of the rounds that look like it is bulged on one size. Used to see this all the time when I used to run jacketed and did not figure out that the Lee die had a 0.308" expander in it.

[JeffG]

They may be calling it something else or I'm too dumb to know it something else may be the same. For example I'm not positive what the dimensions on an M die for a .303 British are so I may just be fumbling around here like the lost human being I am.

Lyman isn't offering their .31 cal M-die?

Larry Gibson

[JeffG]

Very good to know and that is exactly what I have. I should have gotten the RCBS set instead of the Lee like my instinct told me. Oh well, they'll get used one way or another.

JeffG: If you are using the Lee die set be aware you might have to open up the center of the seating die to accommodate a .314 lead boolit. My Lee seating die would only take .311+ so I had to rework it a little to keep it from sticking a boolit or sizing it down. Newer dies may be different than mine. Just a heads up. GP

[JeffG]

Thanks Larry. So, if I understand this, the bushing die tool essentially neck sizes only, similar to a collet die but with more size control depending on the bushing you use? I looked at the Redding site and note for 7.62X39 they mention bushing sizes .328 to .336, which I assume is the outside measurement of the neck. So, if that is true should I be able to measure the inside and outside diameter of the sized case neck and figure out what size bushing I need to get to size it back down to where I want? Is there a discernible amount of spring back after sizing I would need to take into consideration?

Thanks for your patience.

Uh, aren't we talking a MN here? It's not like any milsurp MN, not even the SAKO M39s or the Russian 91/28 snipers, are going to tell the difference in neck tension. I have already played that game as I have a Redding bushing die for the 7.62X54R and can get any amount of neck tension desired. I have tested neck tension using necks sized (inside diameter) from .310 to .3135 using .314 sized .311466s, 314299s, GB 314291s, GB 314041s and sized down 323470s. I could discern no accuracy difference with necks sized .310 - .313. I've use the .31 M-die since with complete satisfaction in any cartridge (54R, .303 Brit, 7.65 Argen, and 7.7 jap) taking a .311 - .314 sized cast bullet.

However, that being said I do like to not work the necks too much to increase case life so I usually use a bushing die for all those cartridges and size the necks to give .002 - .003 neck tension which is generally sufficient for feeding from the magazines in those rifles. With those the Lee case mouth expander die works quite well.

Larry Gibson

[JeffG]

Good idea. I did size FL a case with the Lee FL die while working on the slugging and you aren't kidding, it worked the **** out of the brass.

The M die you want is listed for .303 Brit and 7.65 Arg by Lyman, or just get the 31R expander if you already have an M die body. You will still be working the brass a lot since the Lee FL die is going to size down the neck so far from where you want it no matter what expander is in it. I would use Larry's suggestion of Redding bushing die and Lee universal expander die.

[JeffG]

I'm going to check mine a little closer. Interestingly, I sized a new WW brass with the Lee FL die and the inside neck was .310.

The problem with using the Lee flair tool is the bullet is not going to seat straight. Seat some half way into the neck and tell me what you see. You are going to see a few of the rounds that look like it is bulged on one size. Used to see this all the time when I used to run jacketed and did not figure out that the Lee die had a 0.308" expander in it.

[tomme boy]

Maybe they finally listened to everyone that the 54R uses 0.310" bullets.

[tomme boy]

Pull the expander rod out of the die and measure it would you please? It would be nice to know if they have figured this out.