Sizing die leaving a rub mark

[daverich4]

I’ve been loading for a long time and this is the first time I’ve had this problem. I haven’t loaded 38 specials for many years and recently got a set of RCBS dies for my Dillon 550C to set up to do that. I’ve been loading 357’s regularly without problems but I got a separate tool head / powder measure / dies as I don’t like making a bunch of adjustments in between calibers. The new sizing die is leaving a shiny scuff mark part way down the side. The brass in the pictures is tarnished a little as it’s been in a box since I cleaned it 6 years ago. The mark only goes about half way around and I can’t feel any lip to it at all. I probably would ignore it if it went all the way around but this doesn’t seem right. Any ideas? Thanks.

 

[twodog max]

Never seen that before and I have been reloading over 50 years. Makes me think the sizer is out of round but hard to say.

 

[Pisgah]

Makes me think the last revolver that brass went through had one slightly bulged chamber...

 

[6string]

I've seen that before, with Lee dies.
You probably have a sharp edge on the leading edge at the top of the carbide ring.
This is probably happening when you extract the case from the die. The distance between the rub mark and the case rim is likely just a little more than the width of the czrbide ring and the thickness of your shellplate rim, assuming you've adjusted the sizing die to be just shy of touching the shellplate.
That can be dressed out with industrial diamond paste and a lapping tool.
Or, you can call RCBS and ask them to fix it.

 

[Mike0251]

Also try inserting a case fully into die with lock nut loose. Then tighten with case engaged.

 

[WR Moore]

I can't help but wonder why, if you're using a Dillon, you wouldn't use the Dillon dies?

 

[gwpercle]

Does this mark appear on every case , reguardless of brand ...
Once fired range brass and/or new brass ?
Gary

 

[daverich4]

Does this mark appear on every case , reguardless of brand ...
Once fired range brass and/or new brass ?
Gary

The brass is once fired Starline brass that was new when I bought it. It’s on every one of the first 50 rounds that I’ve loaded.

 

[daverich4]

I can't help but wonder why, if you're using a Dillon, you wouldn't use the Dillon dies?

Habit, I guess. I started with RCBS dies more than 40 years ago and never had a problem before. I’m not having problems with any of the other calibers I load with RCBS dies on the Dillon.

 

[daverich4]

Makes me think the last revolver that brass went through had one slightly bulged chamber...

I would think if that was the case most of the cases would not have shown the mark but every one of the 50 I loaded to start with had it.

 

[daverich4]

I've seen that before, with Lee dies.
You probably have a sharp edge on the leading edge at the top of the carbide ring.
This is probably happening when you extract the case from the die. The distance between the rub mark and the case rim is likely just a little more than the width of the czrbide ring and the thickness of your shellplate rim, assuming you've adjusted the sizing die to be just shy of touching the shellplate.
That can be dressed out with industrial diamond paste and a lapping tool.
Or, you can call RCBS and ask them to fix it.

Thanks. I think I’ll try the die I use for 357’s that doesn’t have the problem and if that works, your suggestion to contact RCBS is what’s next.

 

[pistolpete10]

I can't help but wonder why, if you're using a Dillon, you wouldn't use the Dillon dies?

I kind of like RCBS better than Dillon, they are easier to adjust, especially seating depth.

 

[ggibson511960]

That looks to be happening on the outstroke as the edge of the carbide ring pulls upward and is not co-linear with the ram. In order of probability, crud or burrs on the die locking ring surfaces, crud or burrs on the shell holder, mis-installed carbide ring, bent or mis-aligned press ram (not likely). DO NOT polish on the carbide ring unless you see an obvious burr or piece of ceramic sticking into the bore of the die. Even if you feel competent to polish out a defect, returning to RCBS would be the safer bet. Start with the easy stuff. Make sure the lock ring surfaces and press surfaces are pristine, then cast a critical eye at the shell holder and its mount to the ram. Install the sizing die loose without the lock ring tightened, run in a case bumping as you go to make sure the die centers in its thread fit, then tighten the ring. This is good practice with all dies to make dead certain the ram, shell holder, die and case are exactly co-linear. This kind of foible is why so many of us like Forster CoAx presses. The only time I saw problems remotely like this was with range pickup .45 ACP or 9 mm brass with bent heads from rough handling in an automatic pistol. I doubt a good S&W or Colt will bend heads.

 

[mikld]

My first guess would be bulged cases. The sizing die has a fixed ID (carbide ring) and does not change, so the only variable is the brass. I would measure the case OD in a few places looking for a bulge. I would probably lube a few and see what happens. I don't have a Dillon so I have no opinion about any possible press problems causing the scuffing (off center?)...

 

[H Richard]

I would try some new unfired cases and see what you get. If no marks, no problem, but the last gun your brass was shot in may have a cylinder problem.

 

[2152hq]

Run a brand new factory loaded round into the die (if it can go completely into the die) and see if the same thing happens to the brass.

Yes I know,,,A loaded round!!,,
You run them into the seater die all the time.

 

[243winxb]

Starline 357 brass issue.

My 357 Starline Brass will do that about 3 out of 50. A tiny bite of lube on fingers, applied to brass, will stop the galling, when sizing with my 1970s RCBS fl carbide die.

Galling is a form of wear caused by adhesion between sliding surfaces. When a material galls, some of it is pulled with the contacting surface, especially if there is a large amount of force compressing the surfaces together.

Old "brass" brands of Rem, Fed, Win have never had this issue.

OLD Nickel Rem brass fired many time, now sticks in chamber, after firing. The nickel does not spring back like "brass"

 

[Model19man]

I've seen that before, with Lee dies.
You probably have a sharp edge on the leading edge at the top of the carbide ring.
This is probably happening when you extract the case from the die. The distance between the rub mark and the case rim is likely just a little more than the width of the czrbide ring and the thickness of your shellplate rim, assuming you've adjusted the sizing die to be just shy of touching the shellplate.
That can be dressed out with industrial diamond paste and a lapping tool.
Or, you can call RCBS and ask them to fix it.

Well this isn't Lee dies is it?

 

[TheTinMan]

Dave - did you clean the interior contact surfaces of the die before using it? Captain Obvious here just asking what probably is a dumb question…

 

[dogdoc]

Try another die or try that die in another press if you have one)May be cheaper than sending off. Maybe get an inexpensive Lee die while that one is returned(unless another cause is found)