Using an O-ring on the resizing die – what is your experience?

[jlow]

This is an off shoot of a discussion in another thread on the COAX. I’ve been interested in this for a while but am a bit puzzled by the idea.

In general, I buy into the idea that putting the O-ring between the die locking ring and press allows the die to self-align since it has a bit of free float. The question I have is when you put the O-ring there, how hard do you torque down on the locking ring? I would think you do not torque down a lot since that would basically swish the O-ring? The problem then is if you do not torque down then the lock ring is not really locking is there a chance that it can move and unscrew. The other problem is with the squishy O-ring there when you do a FL resize and bump the shoulders back, does this affect the consistency of the bump?

 

[amlevin]

When you use the o-ring, there is no movement upward when sizing, only a slight amount of lateral "sway" which is allowed by the thread clearance. If you put a witness mark on die, lock ring, and press, there will be no variation from your setting as long as the marks remain lined up.

You can also put a Lee Lock ring under the regular lock ring and accomplish the same thing. The benefit of using the Lee lock ring is that the grove will keep the o-ring a little more under control.

 

[jlow]

Hi Amlevin,

The way I visualize it is when you FL resize are you not putting a lot of upward pressure on the die? But now with the O-ring there, there is a compressible material there and not hard metal, so depending on the amount of force needed i.e. how hard the case is to resize, would the upward force not be potentially different and so possibly the degree of bump? No firsthand experience but just thinking through the logistics.

I always use the witness mark idea but as a Type A, that still bothers me but the idea of putting the Lee locking ring under the regular lock ring is a great idea.

 

[mr45man]

I use a few Lee dies for handgun case prep.
Never liked the O ring thing and replaced them.

After all the "O" ring brought down the space shuttle
John H.

 

[BoydAllen]

Given the cost of the O ring, why not just give one a try? I think that you may not understand that just because lock rings can be tightened solidly against the press, that that may not be necessary or even desirable. After all, it is the threads that take the load of sizing, and the adjustment of the die within them that sets the shoulder bump. As long as the die does not rotate, the setting will remain constant. The O ring provides enough friction between the bottom of the lock ring, and the top of the press to keep the die from rotating even when the lock ring is only tightened enough to slightly compress the O ring. Tests have demonstrated that this sort of "float" can improve the straightness of sized cases, although there are larger issues that need to be addressed if this aspect of reloading is to be optimized. I have switched the lock ring that came with the FL die that I use for my 6PPC for one of the Lee units that has a built in O ring, and have seen a slight improvement in the concentricity of my sized cases, although they were pretty good to start with.

 

[jlow]

BoydAllen – yes, I am actually thinking of giving it a try, just trying to get those potential logistic issues wrapped around my head a little and thought that you guys can give some perspectives to help.

I actually have a few of those Lee lock rings with the O-rings round since I use some of their dies for pistol reloading but switched them out for Hornady lock rings which I like a bit more but that is pistol and I don’t really have any issues there. I think with amlevin’s idea of the double lock, I am pretty comfortable with the no movement idea now. Thanks for guys for you inputs –very useful as usual.

 

[savageshooter86]

Anyone tried the other suggested trick in the other article on concentricity about replacing shell holder reataining pin with a o ring too? Said it may help the shell holder "float" and help concentricity too.


Like I mentioned in other thread that lead up to this thread..... does this only apply to FL dies or would any benefit be seen using it on a seating die and a body die also?

 

[BoydAllen]

Evidently I skimmed over his mention of using two lock rings. I should read more carefully. As it happens, I use that setup on my range press and 6PPC FL die because I use a small set of brass over and over, and have to adjust the die to maintain the same amount of shoulder bump as the brass progressively becomes more work hardened. By setting up the die and lock rings so that the total range of die settings that I might want to use fall within the range of just enough O ring compression, to some point before the Lee ring goes metal to metal on the press, I am able to get to an initial position that is fairly close to my final adjustment more quickly. I thread the die into the press to the point where the O ring is only slightly compressed, and start sizing, checking bump, and adjusting from there. Because the setting for brass that has been fired and sized a lot (note precision term) is different from what is needed for newly fire formed brass, I take the die out of the press at the end of every range session, and reset it for whatever batch of brass that I happen to be working with, the next time that I am reloading (almost always at the range). After I have the Lee ring where I want it, I hold it and the die with one hand, and screw a Hornady lock ring (that I put on the die before the Lee) down into contact with the top of the Lee ring. At that point, tightening the Hornady ring spreads it slightly (due to the V threads) jamming the two rings securely together, while at the same time securing them both to the die.

 

[amlevin]

jlow-

Picture the die in the press. When raising the case into the F/L sizing die, yes there is a lot of pressure. It is up against the threads on the press and away from the o-ring. The only time there is any pressure applied to the o-ring is when withdrawing the case from the die.


Boyd-

This is where witness marks and the double lock ring work. The benefit of an o-ring in the Lee lock nut, locked in it's relationship with the die, and the witness marks that show that you have returned the die to exactly the same position, thus the same shoulder bump, etc. If one is real clever they can add more witness marks on the press to show specific changes in settings. More or less setback in thousandth's, just like a Micrometer dial.

The top of my RCBS press used to look like a clock dial until I put the Hornady LnL conversion in. The adapters have an o-ring designed to lock them in place but they seem to work much like the o-ring when used under regular die lock nuts. Also makes for some quick die changes 8)

 

[BoydAllen]

I have made the same change to my Rockchucker, and I like it very much.

 

[jlow]

Thanks a lot for the great suggestions guys! GREAT STUFF as usual!

BoydAllen – I like your trick with using the Lee O-ring lock ring to allow quick adjustment to headspace! Will have to use that trick.

Amlevin – I am thinking through this a bit so bear with me. So I am going to go through both situations with and without the O-ring.

Without the O-ring and with just a lock ring, my guess is when you tighten the screw on the lock ring as BoydAllen said, it will give a slight bit of compression due to the V threads on the lock ring and in essence there is almost no wiggle room in there for the die against the press say compared to just screwing the die into the press where you can get some wiggle due to some play in the V thread, these will now be gone.

OK, now if you have the die in the same press, the Lee O-ring lock rings in but not too tight, and a real lock ring on top when you tighten the screw on the lock ring, it does take some play out but only from the Lee O-ring lock ring and the O-ring allows the wiggle room between the die and the press to remain, is that it?

Was putting a Midway order in and order a couple of Lee Breech Lock Quick Change Bushing without the die locking rings, that should allow me to try this trick with my Lee Breech Lock press.

 

[BoydAllen]

I think that you've got it. The only problem with the Lee rings is that there is nothing to lock them to the die, which makes it easy to loose a die's setting as you remove it from the press. By adding a conventional split lock ring above the Lee, you lock both to the die, and retain all of the advantages of the Lee. If you are in a situation where you are loading a large number of cases, and your die setting is stable, because you aren't shooting and sizing each case as many times, as is common in short range benchrest, then using some kind of index marking system gets you back to where you were quickly.

 

[jlow]

You are right about the Lee ring which is why I always replace them with the Hornady. More recently having gone to a Lee Classic Cast Breech lock Single stage Press, I’ve been using their Quick Change Bushing with the Die Lock Rings but for this application, I am going to use the Lee Breech Lock Quick Change Bushing which does not have the die lock rings – should be interesting and I am looking forward to trying it – thanks again guys! You don’t disappoint!

 

[offgrid]

Been using the the O-ring method for the last two years under a FL sizer and body die, sized 7000+rds. Putting a reasonable amount of torque on it. Easy to precisely control the amount of bump, very consistent bump. Use a comparator stand/dial indicator and a modified Sinclair comparator body to measure bump.

 

[jlow]

Thanks! Always good to hear of success with the method.

 

[FroggyOne2]

This winter I am going to start using my Dillon 550 for prepping and loading brass.. the "O" ring method is the way that I am going to do it.

 

[Zia Hunter]

I use O rings on my FL dies that use an expander plug. I place the O ring between the die body and lock ring on the decapping rod. This allows the expander to float as it is being drawn though the neck. This has reduced runout.

 

[amlevin]

This winter I am going to start using my Dillon 550 for prepping and loading brass.. the "O" ring method is the way that I am going to do it.

There's also the Whidden floating die tool heads for this press. Allows for alignment of the Sizing die AND the seater die.

http://www.whiddengunworks.net/floatingdiebuynow.html

 

[jlow]

How effective have you guys found this method for seating? Just wondering since that seems to usually require not a lot of force and so whether there is any real "float"?

 

[FroggyOne2]

This winter I am going to start using my Dillon 550 for prepping and loading brass.. the "O" ring method is the way that I am going to do it.

There's also the Whidden floating die tool heads for this press. Allows for alignment of the Sizing die AND the seater die.

http://www.whiddengunworks.net/floatingdiebuynow.html

I am aware of them.