Dillon 750 Decapping and Priming Issue

[jackstrawIII]

Hey,

My friend bought a 750XL and I'm helping him get it set up. After MANY hours of setup, we're finally making some 38 special plinking rounds.

That said, we have two issues, both relating to primers:

1. About 10% of the time it's not removing the old primer. 90% of the time it works fine... but sometimes it doesn't. I cannot understand how this is possible. It seems like it should always work, or always not. Any ideas?

2. The primer seating depth is ALL OVER THE MAP. I started pulling the handle fully down, then pushing it fully forward... but it's still not seating all the primers all the way. Sometimes it does... other times it doesn't. Again, I'm just confused. Is there some setting or something I missed in the 4,000 steps it took to set this thing up?

Appreciate any ideas. Thanks.

 

[THEWELSHM]

Send it back to Dillon mate..

thewelshm

 

[jackstrawIII]

Send it back to Dillon mate..

No way, not after I spent 17 hours setting the darn thing up!!

 

[ATCDoktor]

We don’t have any info on what you’ve done to troubleshoot so far and without knowing what you’ve already done this is going to be tough to fix via the internet.

That said, I’m gonna give it a shot.

Based on what your sharing with the group, I would say you have a problem with the shell plate not being tight enough and flexing under pressure.

Tighten town the shell plate till it won’t turn when cycling the handle and then loosen it till the plate moves with little to no resistance.

That ought to fix your primer depth issues.

Reference knocking out the primers, after tightening up the shell plate, run your sizing die down till it just barely touches the shell plate and back it off a quarter turn or so.

Then run the decapping stem down till you get 100% primer removal and then lock the stem in place.

If the shell plate is already properly adjusted, I’d call dillons help line and have them talk you through the set up.

 

[Unclenick]

Dillon has that unique spring snap-back decapping rod assembly. Make sure it is in order (may want to disassemble and clean and lube and reassemble) and is turned in deeply enough.

The Dillon priming system you have can have difficulty with some brands of primers. In the late '80s and early '90s, CCI primers would seldom seat fully in mine, but Federal and Winchester worked. CCI fixed their cup burr problem in '92, IIRC, but some primers are made that are pretty stiff. The Russian Tula plant primers, for example, are, appropriately enough, a bear to seat.

One other thing that occurs to me that could contribute both to decapping and primer seating problems is if you got a batch of 38 Special cases with crimped primer pockets (there seem to be more crimped primers around these days, even in non-military ammo). In that case, the crimps will need to be removed before primers will seat well. Also, if the brass is of foreign origin, its primer pockets may be a fraction of a thousandth tighter than domestic primer pockets, in which case swaging or reaming the primer pockets may help.

Finally, on my Dillon presses, I generally seat a primer by giving the handle a bit of a shove forward at the top of the stroke to ensure a high primer hasn't stopped it. Dillon's attempt to lower the mechanical advantage until you can feel the primer seating goes a little too far, IMHO. I'd rather have more leverage and an adjustable seating depth stop for the handle.

 

[jackstrawIII]

ATC and Unclenik, that's great info from both of you. I'll give that a shot next time I'm there, hopefully the next few days. Hoping to get this sorted.

One additional question, I shot the test batch of loads we made the other day, and got a few FTFs. Could the issue be that the primer was seated too deep? I wouldn't think that a revolver (S&W 65) would be overly sensitive to primer seating depth, but maybe it was?

Thoughts?

 

[Hammerhead]

High primers cause FTF.
They should always be seated to the bottom of the primer pocket even if they end up looking too deep.
When they're high, they waste some of the firing pin's energy by seating deeper when struck.

 

[jackstrawIII]

High primers cause FTF.
They should always be seated to the bottom of the primer pocket even if they end up looking too deep.
When they're high, they waste some of the firing pin's energy by seating deeper when struck.

This is fantastic news. I'm sure the primer seating issues (not seating fully) I was having caused it. That's great. This problem is a lot easier to fix than primers seating too deep.

Thanks.

 

[Kevin Rohrer]

I bought one last year and have not had these problems.

1. Make sure that you extend the ram all the way to the top of the stroke, then manually adjust your deprimer die do it punches-out all primers. Also make sure the black die plate is set tight enough not to wobble.

2. Make sure the black die plate is set tight enough not to wobble. Also make sure that your top stroke goes as far as you can. You should be able to feel the primer seat.

 

[lll Otto lll]

To ensure consistent priming....the bench must be rock solid, the mount must be solid, and the press must solidly bolt down to the mount. Anything loosey-goosey will cause issues.