AutoPrime II

[Fyodor]

Hi folks,

I finally got a nearly-mint AutoPrime II.

While fiddling around and examining the machanics and philosophy behind its use, I found out why they discontinued it.

It comes with two seating stems, large and small. Because it uses standard shellholders and the feed trough of the pro1000 feeding system, there is on systematic problem on it while seating small primers.

The hole in all shell holders is large enough for large primers and a bit more. On the RamPrime the seating stems have a spring loaded ring around the primer that holds it in place and moves back when the primer is actually seated into the case. Because the seating stem of the AutoPrime II has to fit through the chute of the pro1000 feeding system, this feature isn't there on the AutoPrime II.

So the primer is liftet for about half an inch, sitting on a polished surface that's barely larger than the primer itself, and travels through a canal that is nearly three times the diameter of a small primer.

If the AutoPrime is rocked during this process, the bench felxes, or the press isn't mounted square, the primer can and will slide of the seating stem, falling into the canal. Nothing happens up to now, you just didn't seat a primer. But when you now lift another primer, the previous one will push it of the seating stem to the other side of the canal. Again, you didn't seat a primer. If you try a third time, the canal is full, and you would either squish the three jammed up primers in the canal, which could set them off with a little bad luck, most probably blasting all primers in the system. Or, if you work more cautious and stop, lower the ram, a FOURTH primer is fed, now jamming it up completely.

It took me ten minutes, just to get the jammed primers out without squashing them, because it locks up everthing. You cant remove the shell holder without squashing a primer, you can't remove the chute without removing the shell holder, and the primers are interlocked so they don't want to just fall out when you turn it over.

This problem is for small primers only, but if you work fast, and don't check every case for a correctly seated primer at this time, you might cause a chain reaction richt in your face.

I've designed a small insert into the shell holder, that would guide small primers without leaving them space to slide off the seating stem. When I found someone who would make one or two for me, I'll post a picture and report again.

140403_autoprime2-guide.png

[Zippidydoodah]

Forward it to Lee, maybe they will adopt your idea and give you a prototype. It would be good pr for them, and you probably could help them on other fixes or design improvements.

[Fyodor]

The AutoPrime II is discontinued, and they don't have stock left. So I doubt they are interested in any improvement. I still give it a try, worst thing that could happen is that they reject.

[Steve]

I don't have my auto prime II anymore, but I did not have the problems you are refering to. All I used it for was small primers and the only problem I had was I had to tap on the primer tray to keep the primers feeding. I used it on a Lee turret press mounted solidley on a work bench. Maybe something is missing on your auto prime, or the trough is worn.

[Fyodor]

@ Steve:

No, the problem is after the primer is lifted out of the trough but before it is inserted into the primer pocket.

I have a hand press, and even there it worked nicely a few times. But when just one primer slips off the seating stem, and you don't realise that imediately, you will squash it or lock up the press.

I'm going to test this mod and see if it works. Because this thing is way more comfortable than the RamPrime, especially on the hand press.

[Fyodor]

I got an answer from John Lee personally on that topic.

The official reason why this product has been discontinued are the seating stems and the spring. They originally were from a different product that has ben discontinued, and the die body was very expensive. Sales were never very large anyway, so they stopped making it.

But he confirmed that this problem exists, when you either use a weak press or your bench flexes too much. The primers are not positioned at all after they exited the feed trough. So he appreciated my approach to solve the problem, but they won't make prototypes and test it, because they won't start production again anyway.

I got someone who's able to make these thingies for me. He's got a small business for making RC models and small scale enginges for those, so he's used to small parts. He'll make ten of them, so if they work, I got nine left .

[akuser47]

Cool keep us posted.
That reminds me i need to rebiuld my dtx .18 motor thanks for sharing