Lee expander mystery

[16in50calNavalRifle]

Loading some loads for fun/practice with a Colt snub revolver. I use 357 brass to reduce carbon build-up in the chambers. Here are the specs:

*Caliber: 357 mag
*Lee carbide die set using riser and Lee Pro Auto-Disk with the Adj. Charge Bar
*Mixed brass
*Bullet: 130g FMJ (nice pulled bullets I got from longdayjake/Rocky Mtn last year)

Dies are adjusted per a previous loading session that established proper settings for all dies for this bullet with 357 brass. I measure die position using calipers, measuring up from the lock-nut to the first available "ledge" or reference point.

Mystery: in loading my first 50 this time, all was well until about the 30th round, at which the powder/expander die started belling the case so much that the bullet would fall in a 1/4 inch - massively excessive belling (easily visible to the naked eye). I checked the die - it was set per the previously established settings, lock-nut secure, little piece of masking tape I use as index marks on dies had not moved.

So I unscrewed the powder/expander die out a bit. Belling returned to normal. For about 10 rounds; then the excessive belling resumed. I unscrewed the powder/expander die a bit more - no change, still excessive belling. So I called a cease fire to ponder the mystery and seek advice.

After re-sizing, the brass has a normal case-mouth, so I'm sure it's the powder/expander die at issue here.

I cannot figure out what would change the belling of a case other than the die position in the turret (how far it was screwed down in). The excessive expansion is pretty uniform with different brands of brass, and is so substantial that differences in case length would not explain it, so it seems the die is the problem.

Ideas?

 

[gamestalker]

I can't imagine what type of problem with the die would cause that? The first thing that comes to mind is inconsistently trimmed brass, and to some extent, different brass head stamps, thus varied thickness.

Other than those possible causes, make sure you are using a full stroke when adjusting the die.

I hope you find the cause.

GS

 

[Havok7416]

I occasionally have a similar problem when I change powder measures (I have one old one and several new ones). I have never had the exact problem you are describing though. It does sound like the expander is slipping a bit in the die or something after a few rounds have been processed through it. I would call Lee and let them know about the problem, they may be able to help.

 

[Rushthezeppelin]

If anything I have had the exact opposite problem with my 9mm Lee powder through expanding die. Not so much it changing mid session but last time I jumped on my pro 1000 I had trouble with my first few rounds wanting to shave and discovered my expander die wasn't were I like it. I have to crank mine all the way down to get enough mouth belling to seat (and more importantly not swag) Bayou Bullets 150gr SWCs which go DEEP into the case (its a bear with some cases getting them off that expander though with such a deep setting).

 

[tightgroup tiger]

There is a Knurled finger nut in the center of the riser. Is the nut screwed up to one of it's extremes and locked? If it is in the middle of the threads just left to float then gravity is pulling it down on the threads every time you run a case through it. This is lowering the powder die and measure.

I screw the nut on mine up to the top of the threads and lock it in place then set my flare by adjusting the entire assy up or down in the die itself.

Did you trim your shells to so they are all the same length, that means a lot when trying to get a consistent flare and crimp. But I think your problem is in the center adjustment.

 

[Reefinmike]

Umm did you check case length on the offending cases? A longer case will have a larger bell than a normal trimmed length case. Example- set up your die on using a short hornady case. Then expand the longest case you can find. The difference will be obvious.

 

[16in50calNavalRifle]

Thanks all for your suggestions.

Reefinmike, as I said I have not had this problem before when using the same sorts of mixed brass, and the difference in flare is so large that I don't think case length can account for it - but I will measure some cases and experiment anyway. Thing is, in this session I had 2 or 3 examples of normally flared/loaded cases of the same headstamp for each 1 that had the problem. So headstamp/case length doesn't look, at first glance, to be the difference.

Tightgroup, my first suspicions were centered on that riser/die combo. Thing is, it's set up the same way it's always set up for the 4 calibers I load (again, never had this problem in two years of reloading). I will look at it and see if I can figure out what you are saying and make adjustments.

I will get back to this later today and with luck report a resolution back to the forum.

 

[ranger335v]

You seem to use the terms "belling" and "expanding" interchangably but they are not the same things. The only way bullets can suddenly drop 1/4" into properly reized cases is if the expander has suddenly gotten larger or the bullets have suddenly gotten smaller; both are very unlikely. Therefore, it sounds like you probably have a failure to properly resize problem.

 

[16in50calNavalRifle]

ranger I understand what you're saying - Lee calls their charging dies "Powder Through Expanding" dies. These dies bell the cases as powder is dropped in. In any case, all the cases coming through the sizing die appear normal, and 30 of 50 worked normally. The variation in belling - again, far far greater than would be accounted for by varying brass thickness or small differences in case length - occurs with the powder die.


Will go fool around with things one more time, try to see if the riser is the problem, then contact Lee if all it's still no-go.

 

[Rule3]

Take the die apart and clean it and the insert inside. It may be gummed up and sticking

Reinstall and set it per the instructions. Use the little flow through cap instead of the powder measure and riser (just to see if the dies is now working correctly) and flare a few cases.

If it works OK, than take the flow through top cap off and install the riser and powder measure. You may have to tweak the die body a little

 

[16in50calNavalRifle]

Good idea, Rule3! Shoulda thought of that - take the riser/powder measure out of the picture and see what happens.

Well, hmmm. A while ago I had a few minutes, disassembled/wiped reassembled and screwed in the die (with riser and measure) to the prescribed depth I have previously developed for 357 cases. First test runs were normal. Made sure to use different headstamps with at least some difference in lengths.

Hope to go try another session this evening. We'll see what happens.

Again, thanks all for the excellent ideas. This place is a tremendous resource for reloaders.