Most reloaders have heard of the RCBS Lock-Out Die. This device will allow the reloading press to cycle normally when there is a proper powder charge, but will “lock up” the press if there is too much powder in the charge, or not enough powder in the charge (including no powder – a “squib load”). The die also allows the press to cycle normally when there is no case in the station where the lock-out die is installed. If you are like me, you may have wondered- OK, so how does this thing work? A fascinating device it is for sure!
In this series of articles, we’ll dig into the theory of operation, understand the parts that make up the assembly, learn how to use and adjust the die, and also do a tear down so that you can learn how to clean and adjust or fix the die.
So before we do any more talking, let’s take a quick look at a simplified diagram of the RCBS Lock-Out Die which we can use to understand how it works.
Let’s talk about the function of each of these parts:
Die Detection Rod
This is the component which moves upward and downward with the cartridge and contacts the top surface of the powder load via a nylon “foot” which is interchangeable based on the diameter of the case neck for the cartridge being loaded. In the actual assembly, there are 3 parts that make up this component – the upper rod, the lower rod, and the foot. The overall length of the rod is adjustable by means of threads where the upper and lower rods screw together. This adjustment is used to dial in the RCBS Lock-Out Die based on the powder level being checked.
The die body is similar to the die bodies on most conventional reloading dies. This body is knurled on the exterior, and features conventional 7/8″ x 14 TPI threads which allows this die to be used on most any conventional reloading press.
The ball bearings move inward towards the center of the die and outwards towards the outer surface of the reloading die as the die components move. It is the ball bearings (two of them total) which “lock up” the die if the powder level is not correct when a case is present.
Die Case Lock Sleeve
The die case lock sleeve is actuated (moved vertically) by the case mouth. This part also acts as a carrier for the ball bearings via holes drilled in the side.
Parts not covered in this diagram
In addition to the primary components represented in this diagram, the following are also a part of the RCBS Lock-Out Die assembly:
- Spring clip – secures the die detection rod in the die body
- Circlip – keeps the die case lock sleeve from falling out the bottom of the die body\
- Compression spring – keeps the die case lock sleeve under spring pressure (downward) to assist in reset
- Die lock ring with set screw – used to lock die into place and retain setting when removed/replaced in the press
So now that we’ve taken a look at the components that make up the die, we can now talk about how this mechanism works. The basic theory of operation can be summed up as this: When there’s a case present, an “alignment of the planets” is needed for the press to cycle and not be locked up. What are the so-called planets here? These components are the die detection rod, the die body, the ball bearings, and the die case lock sleeve. If these components align, the ball bearings can move inward into the cutaway on the die detection rod, and that allows the die case lock sleeve to move upward in the die body. That’s it- if the die case lock sleeve can move upward with a case present, the press will cycle. If the die detection rod is not in the proper vertical position when the powder level actuates the rod, the ball bearings cannot move inward, and this will prevent the die case lock sleeve from moving upward.
The following diagram illustrates proper and improper powder levels, and how that translates to component alignment:
Let’s take a quick look at these scenarios from left to right:
Correct Powder Level
At far left, we see the correct powder level detected, and the die case lock sleeve has moved upwards inside the die body. This is possible because the ball bearings are “retracted” into the recess on the die detection rod.
The middle diagram depicts what happens when an overcharge is detected. The die detection rod is “too high” and this misalignment causes the ball bearings to interfere with the die body meaning that the die case lock sleeve can not move upward, and the press therefore locks up (powder is compressed by the foot).
The right-most diagram depicts an undercharge (or squib load if no powder is present). Much like the overcharge, the die detection rod recess is not aligned with the holes in the die case lock sleeve, and this prevents the upward motion of the die case lock sleeve.
So you might be thinking- what about when no case is present? In that case the die detection rod moves up when it contacts the press, and since the die case lock sleeve is not actuated, the press can cycle (die detection rod just moves up, then down).
There you have it- mysteries of the RCBS Lock-Out Die revlealed!
Next in this series, I’ll cover setup, operation and disassembly for this die.