I put 12, 30-30 brass in the tumbler, and noticed when they were finished, of the 12 rounds, 9 of them had dents in the case wall - all 5/8 down from the case mouth. Depths varied. When I loaded them they were all new unfired brass, so the dent belongs to me. Is this dent caused by the extractor? OR? All were fired from a Marlin 336. Thanks for the comments.

The dents are probably where the brass hits the back of the ejection port as they get thrown when extracted. I've had a couple of semiauto's that beat the hell out of brass like that. When you deprime/size them, enough of the dent should disappear that it won't affect function.

Another possibility could be excess lube on the cases during the resizing process. I have had the same experience loading 30-30 in a Marlin. It don't take much

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Some collect art; I shoot it!

I have no idea what would be causing any dent during case polishing, in any type of case polisher If you would post a photo it would help as it is really difficult to make even a guess if we cannot see just what you are talking about. Second I own five Model 336 Marlins of various calibers and have had others. Non have ever dented a case on ejection except at the case mouth. My suggestion is to take the gun out and shoot it again and check for dents before performing any reloading operation. Finally, what are you calling a "dent"? Is it significantly deforming the case, or just a cosmetic nick? Again, photos are necessary so we really can know what you are really talking about!

How do you propose the extractor in a Mod. 336, that engages the case rim, could possibly cause denting to the case wall 5/8" behind the case mouth when the extractor only engages the case rim about 1 1/2" behind where you say the dents are located?

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Gunsmithing since 1961

The dents are not from polishing...................

They come from the weapon that they are fired from........
or when they hit the deck.

They should hold up for 5-6 loadings if not too deep.

I had a friend that had a pistol that "Crushed cases"..............
A reloaders nightmare.

Just be glad yours are just "Nicks".

I reload a lot of auto pistol and 5.56.

Mouths/necks: a dent is OK. If it's a crack, crease, or tear, I toss it.

Shoulders: You have to watch here. A small dent will straighten out if full length sized, most of the time. Big dents seen? I scrap it out.

Bodies: These dents come out with sizing.

When in doubt, I run the sized case into a Lyman case gauge. Any problems will be revealed and the brass goes in the trash.

Case necks often get dented on ejection from repeating rifles when the action is worked smartly, and the case neck hits some part of the rifle or a rock or cement floor. Semi-auto rifles can be very bad in this regard, particularly the FN 49 as well as the German G3 and G33 series of roller locked weapons. The older 1911 pistols were pretty bad in this regard too and that is why the ejection port is now much lower on them than on the pistols made before the 80s.

Generally, it will cause no issues for a reloader unless the dent is extreme and actually folds or creases the brass to the point of weakening it.

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Keep your powder dry.

I vote for excess case lube as the cause. Load as normal. The dents will iron out when you fire.

Reloading Tip from old reloader :
Every time you handle cases , carefully inspect them and look for anything ...dents , lines on body , tiny mouth crack , fired primer condition...etc If you know when the dents occured you can more easily pin point what happened .
Example ... Fired cases , picked up off ground and see dented mouth .
Well it happened during ejection or when the case hit the pavement ...
shooting on a soft surface (grass) then it happened during ejection .

Look at your cases every time you handle them ... cases tell a story ...if you are wise enough to read them when written .
Gary

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Certified Cajun
NRA Member

I didn't word my description very good. The dents are not due to the polishing - I noticed them when I removed them from the tumbler. The dents are a slightly sharp ding, rather than a dent. They are not deep enough to worry about because the next sizing will clear them out. I use a single stage RCBS press and inspect each round, at each stage. If the cases aren't dang near perfect after sizing, and I resize everything, they don't get loaded. I would have noticed any imperfection when I removed them from the tumbler. There "pings / dings" would have been caught at that stage. They occurred during loading-firing-extraction. I'm just curious is all - especially when all the dings are at the same location on the case. Been reloading since 1971, and have never noticed this.

So when you work the lever of your 30-30, it extracts the fired case from the chamber. When it gets towards the end of it's stroke, the base of the cartridge hits the ejector and the ejector kicks the brass out of the top or side of the gun. If the ejector is a bit long, the brass will start it's trip out the ejection port before it clears everything. It is hitting on something as it leaves the gun and I think that's what causing the dent. I wouldn't get too wrapped around the axle about it and unless the brass is really badly deformed, I would still reload it. Of course I've made some assumptions here so feel free to set me straight if I missed something.

That is pretty much my thinking also because upon 10x magnification, there is a small flat indenture, not a point, that suggests hitting a flat surface. Another line of thought, that is a real possibility, is that this is a rifle (Marlin 336) that has seen very little use since it was bought new, and loading cartridges thru the loading gate is extremely difficult - like something is binding on sharp edges. I suspect that the pressure of cartridge insertion is creating the case dent in the process. Sure not as smooth as any Winchester. Time for a total breakdown and smooth rough edges.

Could possibly be occuring during chambering of the loaded round.

If the bullet nose strikes the upper chamber wall as the round is being pushed into the chamber,,that can slow or stop momentarily the chambering process.
The case is at an angle, with the base not yet fully up and squarely seated against the breech face.
More importantly the case just back of the neck is pressed against the chamber entrance/rim area at the bottom of the chamber
That can cause the ding in the brass.

Smoothing out the bolt face and especially the short section just below the breech face itself that initially pushes the case forward & off the carrier can help.
Anything to get the case to smoothly slide up onto the breech face from the carrier.

Check the extractor and make sure it's not hindering the case from getting onto the breech face w/o a lot of effort.
But don't make the fit a loose one if you do work it over. That can make extraction and ejection issues for you.
It's a balance betw the two.

Smoothing out any roughness only. Don't remove a lot of matr' from the breech face itself or you will be increasing headspace.

Also seating the bullet just a bit deeper in the case can help.
Sometimes just changing bullet brands makes a difference even though they are adv as the same Flat nose shape.
They can vary just enough to avoid the problem.

The dent can also occur when loading them thru the loading port. Especially if you are used to partialy inserting the rounds each time so the gate don't snap closed for easier loading.

It sounds like it needs a good breaking in. They are great rifles. I've spent some quality time with one in the deer woods of Maine.