Lyman sizing die issue in RCBS Lube-A-Matic

[Matt_G]

Got in 4 brand new Lyman H&I sizing dies last week.
The one I wanted to use today is .410 diameter.
Put it in the RCBS Lube-A-Matic and the nut that holds in the die refused to seat all the way.
There was about a .050 gap between the nut and casting.
Since the die was sitting too high, this caused the bullet to go too far into the die, even with the Lube-A-Matic adjusted for minimum depth.
As such, I was getting lube in the crimp groove of my H&G 258 copy bullets.

Took me a while to figure out what was going on.
I kept looking for foreign matter or something binding and was coming up empty.
I finally realized the issue was the die itself.

If you look at a sizing die, you'll see that the bottom of the sizing die bodies are chamfered.
On these 4 new dies, the bodies are not chamfered nearly enough.
That was what was causing the die to not seat in the casting all the way, which produced excess height and lube in the crimp groove.

Why someone at Lyman would change the CNC programming to make a smaller/shallower chamfer cut is beyond me.
I can't help but wonder if it works with a Lyman 4500 and this change was deliberate.
Now I have to modify all four of these die bodies.


Frustrating.
And no, I will NOT start powder coating.

 

[Winelover]

I don't powder coat, either. I have several Lyman dies that work in my RCBS LAM sizer..................purchased because RCBS's was out of stock As far as I know, they were always interchangeable. Nowadays, who knows where they are being made!

 

[Dusty Bannister]

This first came up several years ago. Not a great move, but you might ask the vendor.

 

[Matt_G]

This first came up several years ago. Not a great move, but you might ask the vendor.

Several years? Interesting.
I had not heard of this issue before.
Oh well, 5 minutes or so with the bench grinder and a pan of water to keep the die cool, and they will work just fine.

 

[Dusty Bannister]

I tried looking for a thread on one of the forums, but did not find it. I think you need to consider the taper on the bottom of the die, not the OAL.

 

[Dusty Bannister]

Major problem w/ RCBS Lub/sizer

I asked in another post if Lyman H&I dies & top punch's would work in a RCBS L/S.. I rechecked today and found that my Lyman sizeing die sticks out above the RCBS body by apx .175 " and there is no allen set screw in the ram body to hold the top punch in place ,like my Lyman . Any thoughts ?

castboolits.gunloads.com

The answer is in the thread.

 

[Matt_G]

Yeah, I just put a better chamfer on the bottom of the die body and they work fine.
No need to shorten the die.

 

[beagle]

When we started messing with adapters for nose first sizers, we encountered the problem. Some dies would’t enter the adapter. Small raised ring on the dies. We ground it off. Not sure about the 4500 theory. Possible.
All my dies are made by a local machinist. Not hardened. RCBS dies are surface hardened but a file will cut through./beagle

 

[castmiester]

I buy used dies off a guy who's pretty knowledgeable. The only new one so far is a S&S oversized .432 but fits fine in my Lyman 450.

Measure the length of one that fits and go from there. Maybe find a machinist. .050 seems alot to do yourself. But as Dusty said the thread has the answer. Different taper angle on the on the Lyman verses the RCBS.

Funny thing with the taper.... I would think that taper really isn't needed ? Or Lyman and RCBS would use some type of seal at the base of the die instead of a taper. Kind of like the pressure screw base isn't sealed. I had to use a pieces of bicycle tire inner tube when bolting down the press to my bench. I don't think the die posses a problem as much as the pressure screw.