Lyman Expander "M" die O-ring Mod

[BLUEDOT37]

I've added Lyman's expander "M" die to virtually all my pistol cartridge reloading sets. I like that their expander plugs are longer (expand deeper) & have the stepped diameter feature, which is particullarly good for loading cast bullets.

One thing that is a little annoying though is making depth adjustments on the fly. The locking nut usually ends up either too loose or too tight to smoothly tweek the final setting. During my last reloading session I got an idea & rummaged thru my parts bin & found an O-ring to try. I removed the expander stem & slipped the O-ring over the tip & slide it over the threads, butting it against the locking nut. Screw the stem back into the body & lightly snug the locking nut down, against the O-ring & die's body. Now, turning the stem's adjustment screw nets a smooth positive feel, either way you turn it. No need to mess with the locking nut again.

The O-ring I used measured: ID= 9/16", OD= 3/4", & thickness= .100". Went to Lowes & found a package of ten #11 O-rings ($2.49) that were a good match & installed them on my remaining dies. It even worked great on my .41 Mag RCBS expander die (new ones are have the "M" die feature too). I did notice, while going thru my die set boxes to see which ones needed the upgrade, that Hornady uses a similar feature, a flat rubber washer, on the adjusting stems of their seating dies, so maybe that was in the back of my mind when I did this?

I dislike the style lock rings (body) that Lyman uses (with the allen head setscrew) & have always changed them out with Lee's Finger Tighten Lock Rings (#90534) especially on dies that are frequently adjusted.

One last item, the Lyman expander tip screws into the stem. I've never been able to keep them tight. It always comes loose in the middle of a batch of brass & wildly flares the brass before I realize what happened. Now when I get a new one I degrease the tip's threads & but some threadlocker on it & haven't had that problem reoccur.

These few simple mods make a great die even better.

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Lyman Expander die mod

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[Rule3]

I love it when folks copy LEE designs

 

[fredj338]

I'm the opp, I swap the crappy lee ring for one I can lock. The idea of a lock ring is to set it & forget it. The o-ring allows movement, small, but still movement. I want the setting to stay, regardless of how many times I remove the die. Just food for thought. Funny how people can look at the same thing & see diff attributes. Not unlike politicians I guess.

 

[Rule3]

I'm the opp, I swap the crappy lee ring for one I can lock. The idea of a lock ring is to set it & forget it. The o-ring allows movement, small, but still movement. I want the setting to stay, regardless of how many times I remove the die. Just food for thought. Funny how people can look at the same thing & see diff attributes. Not I like politicians I guess.

People say that all the time and it flat out not correct. If you snug the LEE o rings down they WILL NOT move. I have enough of them on enough turrets to say the statement is FALSE.

I would much rather deal with them than the lame RCBS with brass heck lock screw that strip and their solution is to send you a bag of them and some lead shot to hole them tight.

 

[fredj338]

People say that all the time and it flat out not correct. If you snug the LEE o rings down they WILL NOT move. I have enough of them on enough turrets to say the statement is FALSE.

I would much rather deal with them than the lame RCBS with brass heck lock screw that strip and their solution is to send you a bag of them and some lead shot to hole them tight.

No they do not move on the press, but as you unscrew them from the press, there is movement. I have used enough Lee dies to know this & have replaced the o-ring with locking rings on critical dimensions like the when partial FL sizing or crimping.
The old RCBS lock rings are krap. The newer split type with screw are full proof as are the Hornady. If you never remove the dies then it really doesn't matter. The Dillon have no locking device. Where it's important is changing out dies often, like with a ss press, & want to maintain your settings.
BTW, Hornady uses an o-ring on their seating dies sim to what BD37 shows on the M die. I like it as it allows minute adjustments in seating depth & will still hold that.

 

[Rule3]

No they do not move on the press, but as you unscrew them from the press, there is movement. I have used enough Lee dies to know this & have replaced the o-ring with locking rings on critical dimensions like the when partial FL sizing or crimping.
The old RCBS lock rings are krap. The newer split type with screw are full proof as are the Hornady. If you never remove the dies then it really doesn't matter. The Dillon have no locking device. Where it's important is changing out dies often, like with a ss press, & want to maintain your settings.
BTW, Hornady uses an o-ring on their seating dies sim to what BD37 shows on the M die. I like it as it allows minute adjustments in seating depth & will still hold that.

OK, you are saying that you loose the setting if you unscrew them from the turret or the press?

Yes, then in that situation I agree then can move .

 

[fredj338]

OK, you are saying that you loose the setting if you unscrew them from the turret or the press?

Yes, then in that situation I agree then can move .

Correct. Moving dies in & out on a ss press demands repeatable settings to avoid spending a lot of time adjusting dies.

 

[BLUEDOT37]

The newer split type with screw are full proof as are the Hornady.

My favorite too, on dies I don't need to adjust the body routinely.
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BTW, Hornady uses an o-ring on their seating dies sim to what BD37 shows on the M die.

Yeah, that's what I mentioned in my original post.

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I agree, the Lee lock ring can change when you remove it. I try to grab the nut, not the body, to start loosening it. Since I use them mostly on expander dies & seating die, those need setting up/tweeking each time anyway so a little slip isn't a biggie to me.

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[k22fan]

The preferred lock ring varies with the situation.

Lee’s system will not work at all in a Bonanza Co-Ax press. Dies are not screwed into a Co-Ax. They slip into a slot. A spring loaded ball retains them loosely enough for the dies to align themselves with the case as the case rises into the die. A lock ring cinched to the die independent of contact with the press is necessary. I like my Co-Ax for rifles for which I have no need for large numbers of cartridges.

 

[TAROMAN]

This one needs double likes!
Great idea, works perfectly.

 

[Maximumbob54]

I use a split lock ring on all my adjustment nuts in Lyman and RCBS dies.

 

[BlueOvalBandit]

Make sure the expander plug inside is not working its way loose from the inside. I was chasing my tail with my M-die over expanding. I'd set it and then I'd have to readjust after a few thousand, thought it was the lock rings, then the plug finally fell out.