Revolver Headspace Question

[AZ_M&P]

I'm starting to make up some loads for my 500 S&W, and I notice that once I resize the (once used) casings they're slightly past the 1.625" maximum case length (1.631"). Since revolvers don't headspace on the case mouth but rather using the rim, do I still need to trim these cases? COL is 2.080", and I'm right there. Should I be concerned about pressure issues and trim the cases down .006", or is this not enough to make a difference?

I'll probably trim the cases anyway, but I'm curious what you all think about it.

Thanks!

 

[series guy]

If the bullet doesn't hang out the front of your cylinder you're good to go.

 

[Wise_A]

Too small to matter, I would say. And also, even if the length was longer, I think the only place you would run into trouble is if you seated a rather long bullet to a cannelure/crimp groove, and managed to make a cartridge that protruded from the cylinder.

You'll see the same thing in some other medium- and big-bore revolver cartridges. Some data manuals list a shorter trim-to length for use with the Hornady FTX bullet.

 

[342ti]

The longer the cartridge, the less pressure, so you'll have no issue with longer cases. Don't think it to death Man, enjoy one of the many pleasures of shooting revolvers, the cylinder length keeps OAL honest! If it spins, it Wins!

 

[stansdds]

As long as the case mouth crimps into the bullet's crimping groove and everything fits and functions through the revolver, you should be fine with slightly over-length brass. Straight wall handgun cartridge brass, once trimmed, will usually not stretch, so trimming is a one time deal. Personally, for plinking ammo in revolvers, trimming is a waste of time, but for target loads it does aid in achieving consistent roll crimps.

 

[M29since14]

I'm with you. Trim them. There's a reason that cartridge brass has a maximum length. It's for your safety. I wouldn't ignore it with any round, and particularly not with a high-pressure round like the .500 SW.

 

[2152hq]

I'd wonder why the cases are stretching .006 past Max AOL with one firing.
(..Did they start out being at Max 1.625 and stretch out .006?
or were the cases at an unkn length and stretched to 1.631)

IF.. they do that (stretch .006) with each firing, reloading/resizing, you'll have a good chance of head separation after just a few reloadings.
4 reloadings will stretch the brass nearly .020 to .025. It'll most likely separate above the head from that.

Wether the .006" case length is 'too long' or not:
It's over spec, you know that already.
It may be that the chambers in your revolver are bit over length in spec too (maybe),,so it's not posing a problem.
But if the chambers are in spec (length) then cases that are too long are not OK.

The mouth of the case is too far forward and is jammed against the front edge of the chamber. That small sharply angled step in a rimmed or necked case chamber.
If they do that, the pressure can build when fired as the crimp can't unfold as it should. Even simple friction and taper crimped cases are effected by it if too long for the chamber.

Old straight-thru bored chambers were not effected by this.
I'll guess that the 500 has a modern chamber cut in it, but personally I've never gazed into one.

It's the first issue of why the cases are lengthening that much with one firing that I'd be looking at.
If you trimmed them and reloaded them again and they did not lengthen the second time, I'd feel a lot better about the load and Headspace.
Continued lengthening of the brass that much with each loading, I'd start looking at the load, headspace, throat dia possibly being too small for the bullet dia.

Just some thoughts. Be Safe!

 

[gwpercle]

They stretch because it's a fairly high pressure round, the case expands to fill the chamber , now they are larger in diameter ...run them through a sizing die, they get squeezed down and the brass has to go somewhere...that's right it goes out the open end of the sizing die ...the only place it can ... which results in a .006 longer case ... Not rocket science so don't overthink it . Trim them .006 if you like but it's not really an issue .
I stopped trimming straight wall handgun cases about 40 years ago , just wasn't necessary ...
Gary

 

[AZ_M&P]

Thanks everyone for the thoughts and advice. I think considering the size of the round I'll still trim (once) just to be safe, but I have to agree that I'm not sure it's needed. That being said, this isn't a round I'm too comfortable experimenting with.

 

[DWalt]

The only handgun cartridge case I have ever trimmed is .30 Carbine, in my Ruger Blackhawk. For some reason. the .30 Carbine case always stretches when fired, and in the Blackhawk, the case headspaces on its mouth. With even a small amount of case elongation, a reloaded cartridge will cause the cylinder to bind. I sort of get around this by trimming the case length a little shorter than recommended, and can sometimes get two reloads before needing to trim the case again.

 

[Rule3]

It's not enough to worry about and depends on how accurate you calipers are.

Specs are 1.625 +/- .010

Your difference is .006" Kind of splitting hairs twice

1.631-1.625=.006


https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf

 

[Funflyer]

It's not enough to worry about and depends on how accurate you calipers are.

Specs are 1.625 +/- .010

Your difference is .006" Kind of splitting hairs twice

1.631-1.625=.006


https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf

Spec is actually 1.625" -(minus).010"

 

[trapper9260]

To me for being over max on the first fire .I say trim and then after you fire them again ,see what they are in length. If did not change much from being trim then you should be ok . If like stated about going over need to check other things.

 

[Alk8944]

First, revolver case length has nothing to do with headspace!

Second, Check case length as-fired. Then, size the case and re-check case length. How much did it grow?

I wish people who do not have even basic knowledge of a subject would refrain from posting comments. The operable phrase is "You learn more by listening than by talking!, or in this case reading.

If this does not apply to you don't whine about this post, it doesn't apply to everyone!!!

 

[Forrest r]

Firearms have freebore/ball throats built into the cylinders/chambers of the firearms for a reason. +/- 20/1000th's is typical and allows for differences in case lengths, crud, etc.

A cut-a-way of a revolver cylinder, you can see the freebore built into the cylinder's chambers.

freebore is the distance from the end of the case to where the taper starts in the throat of the cylinder. If your case length exceeds the freebore then you have a problem.

Also the picture above shows why moving the bullet out (longer oal) is a good thing. The bullet is now aligned in the leade of the chamber rather than being able to wallow/bounce around until it reaches the leade greatly improving accuracy.

 

[Mr. HillBilly]

Cool pic. never saw a cylinder pic like that before.

 

[AZ_M&P]

Firearms have freebore/ball throats built into the cylinders/chambers of the firearms for a reason. +/- 20/1000th's is typical and allows for differences in case lengths, crud, etc.

A cut-a-way of a revolver cylinder, you can see the freebore built into the cylinder's chambers.

freebore is the distance from the end of the case to where the taper starts in the throat of the cylinder. If your case length exceeds the freebore then you have a problem.

Also the picture above shows why moving the bullet out (longer oal) is a good thing. The bullet is now aligned in the leade of the chamber rather than being able to wallow/bounce around until it reaches the leade greatly improving accuracy.

Great pictorial, thanks!