"positive return mechanism"?? Seen on dillon and Lee but not hornady?


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wacki
May 30, 2010, 01:44 AM
Can someone explain what a "positive return mechanism" is? I understand how the Dillon powder check buzzer works but this is apparently something different.

Ultimatereloader.com talks about it and it's 'double safety' here:

http://ultimatereloader.com/?p=635

and there is this post (http://thefiringline.com/forums/showthread.php?t=284802):

The critical weakness that poses the real danger is that there is no positive return mechanism on the powder measure. Dillon has a return bar, Lee even has a return chain. Hornady has nothing! Hornady knows about the problem with the pistol metering insert and told me to just sand it down when I originally had the problem. I thought it was reliable, but then it bit me. A return mechanism would solve the problem.

I assume the Lee Pro has it right?

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dmazur
May 30, 2010, 02:39 AM
I have a Dillon 550B. Dillon refers to this as the "failsafe rod", or "failsafe assembly" in the manual.

My understanding is that the case-actuated mechanism doesn't lack for power as the bar is extended to drop the charge. The user is providing it as he lifts the case into the powder die.

The problem is on the return. As the case drops clear of the die, something has to return the bar to the original "at rest" position. Dillon used to use a spring assembly, then changed the design to the more positive bellcrank and failsafe rod.

This is basically a bellcrank mechanism that guarantees the powder bar returns to zero, making the next powder charge correct (rather than light).

The rod connects to the top of the ram at the "return bracket", and the primer seating motion is used to pull this rod down and operate the bellcrank.

Sorry, but I have no experience with Lee loaders. If there is something that guarantees their powder measure "returns to zero", they are trying to do the same thing as Dillon's failsafe rod. IMO, there has to be something more than a spring or it isn't "positive".

Gryffydd
May 30, 2010, 03:26 AM
I do this crazy thing while I load on my Hornady LnL. I watch the powder measure on each stroke and I look in the case each and every time I place a bullet. Sounds crazy, I know... But then I also don't use a powder cop or lockout die as I'd just as soon pay attention to what I'm doing as pile on mechanical safeties so I can watch the ballgame while I load.

I also have yet to have my powder measure fail in ANY way.

jfh
May 30, 2010, 05:42 AM
The latest version of the Lee Pro 1000 has provisions for attaching its powder charge actuating lever 'drawback;' earlier ones do not have a carrier assembly that will work easily.

The Lee Load-Master uses the same rod-actuated drawback on the powder measure that the Pro1000 version does--IOW, it's a feature of the measure. If you have a Load-Master and using a (Lee) Autodisk measure that is spring actuated, the parts can be ordered and fit to the Load-Master of any age.

The same measure can be set up as the spring-return version. That version is necessary, needless to say, when using the measure on a (Lee) Turret press.

Jim H.

wacki
May 30, 2010, 10:48 AM
The latest version of the Lee Pro 1000 has provisions for attaching its powder charge bar 'drawback;' earlier ones do not have a carrier assembly that will work easily.

Is this what you are talking about?

http://www.midwayusa.com/viewproduct/?productnumber=150005

That doesn't look right but I can't find anything else on midway.

sharptailhunter
May 30, 2010, 11:08 AM
I do this crazy thing while I load on my Hornady LnL. I watch the powder measure on each stroke and I look in the case each and every time I place a bullet. Sounds crazy, I know... But then I also don't use a powder cop or lockout die as I'd just as soon pay attention to what I'm doing as pile on mechanical safeties so I can watch the ballgame while I load.

I also have yet to have my powder measure fail in ANY way.

I must be crazy too cuz I do the same thing. I actually installed a Dillon Powder check on my LNL AP just for extra safety. Still doesn't replace actually verifying by eye. As for the positive return thing, yeah sounds cool. Sounds like a great idea, actually. That being said, I haven't had a single problem with the powder dropper on my LNL. Before the first use, I cleaned it with Hornady One Shot gun cleaner and dry lube to remove the packing oil. I'll tell ya that the return spring is sort of an overkill kill, the whole assembly operates so smoothly that it returns to zero by gravity alone. I've now done close to 3,000 rounds with my LNL AP and it has worked beautifully, I love it!

D Rudd
May 30, 2010, 11:52 AM
This is the Lee mechanism.
http://www.midwayusa.com/viewProduct/?productNumber=129819

Dana

rfwobbly
May 30, 2010, 12:25 PM
dmazur told you right.

I believe there are also additional safety features. Should you go through a half stroke, unlike other brands with direct mechanical operators, the Dillon dispenser will not drop a second powder load into your case. So say near the top of the stroke, if you decide to seat the bullet or crimp a second time, the Dillon powder dispenser will not drop a second shot of powder into your case because the operating lever has not passed through a full stroke.

This helps reduce "double loads". And I don't think anyone else offers anything like this.

You get what you pay for.

loadedround
May 30, 2010, 12:28 PM
I run two Dillon 550's and both have the Positive Return Mechanism(PRM) and the PRM has saved me from the possibility of squibb loads several times when the measure gets dirty and doesn't want to return smoothly.

jfh
May 30, 2010, 12:36 PM
wacki: D_Rudd / Dana called out the correct part description; meanwhile, I have edited my post to change the terminology slightly.

From the Lee help files--"If you received your measure as part of a progressive loading kit, you would have received a bead chain that fastens between the lever on the measure and a hole on the carrier. The chain system is preferred when loading progressively as the chance of a double charge is nearly eliminated. As the case actuates the measure to drop the powder charge, it is not reset until the carrier returns to the bottom of the press. As this is done, the case has already moved to the next station."


As found in the 'Lee Precision Tech Assistant,' under "Auto Disk Return Systems."

Jim H.

Walkalong
May 30, 2010, 12:59 PM
With a sturdy return spring and a clean powder measure, I have never had that trouble with the Redding measures I used on the Projector and now the LNL. Early on I had modified a Hornady pistol powder measure to work automatically on my projector, and I had to keep an eye on it, as it would hag with some powders occasionally. I retired it after I modded things to run my Redding 10X on the Projector, and later the LNL (http://www.thehighroad.org/showthread.php?t=439181). It never sticks.

Roccobro
May 30, 2010, 08:25 PM
Is this another case of reloader inattention = Factory press needs upgrade?

I guess Hornady needs some more of them kinda users to justify an "overkill kill" powder measure update. lol

Justin

evan price
May 30, 2010, 09:58 PM
I load with the old-style Lee auto-disc measures with the spring return. I suppose I might get a double charge if I weren't looking in the case before I seat a bullet.
May be I'm too technologically inferior to be allowed to reload. Maybe I don't want to crank out 500 rounds an hour as fast as I can pull the handle. Dunno.

Walkalong
May 30, 2010, 10:18 PM
Guilty here too evan. Slow and steady, see each charge.

Blind Bat
May 31, 2010, 01:58 PM
I might be wrong on this one because I'm currently about 100miles from my LNL but I believe you could accomplish almost the same thing by putting a spring on the case activated thingy. That said, I don't use a spring. Just gravity. The achilles heal in the LNL isn't the powder measure, it's one of the best rotary measures on the market. The problem it has is the LNL die for the measure loosieing up. I use a wrench to make sure it's tight before I start loading and I haven't had a problem since my first couple of loading sessions. I usually load 300-1000 rounds per session.

Gryffydd
May 31, 2010, 11:13 PM
I'm currently about 100miles from my LNL but I believe you could accomplish almost the same thing by putting a spring on the case activated thingy.
It comes with a spring, but by definition, a spring is not a "positive return" mechanism.

Idano
May 31, 2010, 11:33 PM
IMO this is a solution looking for a problem. I have been using the RCBS case activated linkage, it is the same design as the one that came with my Hornady L-n-L, for over 12 years without a single instance of it not returning once it drops its charge. I bought it to replace the hokey Lee powder measure that came on my LoadMaster and have since moved it to my Hornady. The Hornady and the RCBS linkage both use a return spring to reset the rotor. I don't know about everyone else but I always encounter the resistance from the powder measure long before the seating of the bullet; if it ever did hang up you would feel the difference in the stroke a red flag for any progressive loader worth their salt but that is just my opinion.

jmorris
May 31, 2010, 11:37 PM
All of my Dillons now have them. Some of the older ones didn't because they predated them but were free once they thought of them. My LNL that I owned didn't but it was only a problem with some old "long cut" 3031.

Hey_Allen
June 1, 2010, 08:33 PM
I thought the weight of my LnL powder dispenser alone made it a fairly sure "positive return" since gravity is a nice constant force pulling the whole mess back down.

I've never had a problem with the dispenser staying up, for whatever that's worth.

BigJakeJ1s
June 1, 2010, 11:52 PM
The Dillon fail-safe mechanism, when properly adjusted, does not ensure a full cycle, but only prevents another charge if the press is not fully cycled (the shell plate fully lowered between strokes). The Dillon PM still relies on gravity and spring force to re-cycle the PM once the shell plate is fully lowered, releasing the failsafe mechanism. It is designed to prevent the type of accidents that rfwobbly mentioned.

Andy

dmazur
June 2, 2010, 01:23 AM
The Dillon fail-safe mechanism, when properly adjusted, does not ensure a full cycle, but only prevents another charge if the press is not fully cycled (the shell plate fully lowered between strokes). The Dillon PM still relies on gravity and spring force to re-cycle the PM once the shell plate is fully lowered, releasing the failsafe mechanism. It is designed to prevent the type of accidents that rfwobbly mentioned.


Actually, because the Dillon PM moves sideways, gravity doesn't help cycle it, and the spring is only involved in the mechanism rfwobbly described. From the Dillon manual -

Move the operating handle to the priming
position, press the operating handle firmly forward.
Tighten the blue wingnut (#13799) until the top of the
spring (#14033) just touches the underside of the
return bracket (#13885). We’ll come back to filling the
measure with powder and adjusting the bar. The
purpose of the powder measure failsafe rod (#97000) is
to return the powder bar to its closed position.

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